CASTING. Many operations can only be per formed in the recumbent position, and for the sake of the patient and operator it is necessary to cast the animal. If this is carefully and skilfully done the risk of an accident is very small, but it should never be undertaken with out using every precaution to avoid injury, especially if the horse is a very valuable one, is old, very nervous, or strong-willed.
In many cases it will be found advisable to administer an anaesthetic previous to casting, and the author has no hesitation in strongly recommending this practice, having used it for a number of years with success. It not only reduces the risk of accidents to a minimum, but also facilitates the operation itself, and is more humane for the animal. As there is very little struggling fewer assistants are required to cast and hold the animal, which is a great consideration when operations have to be per A method will be described later for administer ing chloroform standing.
Precautions to be adopted previous to Casting. —(1) A soft bed of straw, sawdust, or tan to break the fall, and if these are not available a grass plot or soft ground well covered with grass.
(2) Capable and sufficient assistance. Usu ally four to six men or more are required, according to the temperament and size of the horse.
(3) Instructions should he clearly given to each man beforehand exactly what he should do.
formed in the country, where skilled men are not often available.
Chloroform is the best anwsthetic, but narcotics may be administered about an hour before the horse is cast.
Chloral hydrate in doses of from one to two ounces dissolved in from one to two pints of water given by the mouth or rectum answers very well, or the drug may be given in the form of a ball. Cannabis indica is sometimes used, and also morphia, but the latter is not so effective for horses as for dogs and human beings. Five to ten grains, according to the size of the horse and the degree of narcosis required, is administered hypodermically. If larger doses are given excitement and delirium often result, also the horse sweats freely, which is objection able for some operations, e.g. clipping.
(4) The appliances should be sufficiently strong and in good order.
(5) The head of the horse should be secured by a halter which cannot slip off, or preferably a bridle. A short twitch may also be applied, and blinkers or blinders put over the head to restrict the vision.
(6) The animal should be fasted for at least twelve hours previous to operation, to lessen the risk of a ruptured stomach.
Apparatus. Innumerable appliances have been used for casting, but it is not my intention to describe them all here; it will be sufficient to give those that are most commonly in use, or have proved most serviceable and safe.
For young animals the simplest apparatus is the casting rope or double side-line, and this is generally used for operations on the under part of the abdomen, such as castration, operations for herniae, etc.
An ordinary waggon rope answers the purpose very well, although special cotton ropes can be obtained with a leather neck-piece having a buckle so that it can be strapped round the neck, and made to fit any size of horse. If an ordinary long rope is used it is doubled in the middle and a loop is made to fit the neck, while the two ends are brought between the fore legs, one being placed round each hind heel from without to within and so to the collar on each side. Some operators prefer the knot to be on the top of the withers, in which case the ropes will not pass between the fore legs.
It is a distinct advantage to use in addition a surcingle with an iron D at each side, round the body, or a strong hemp rope. This rope should have two round eyelet holes let into it, and a short piece at the withers to attach it to the neck rope, so preventing it from slipping over the head during the struggles of the animal, which not unfrequently happens with small thoroughbred colts. The colt may be held by an assistant, or the halter shank may be folded round a post, taking care not to fasten it.
Two men are usually required on each rope, and the colt is cast on the off side first as a rule. The men on the near rope pull forwards, and those on the off rope sideways and backwards. When down, the hind leg is firmly secured by a double hitch, and after running the end through a ring in the surcingle or body rope the fore leg is secured in a like manner.
The colt is then rolled over and the upper legs also fastened, when the operation can be performed.
A back rope fixed to one hind shank and passing under the loins to the other side keeps the legs in the right position, and gives more room to the operator. When on the ground the head should be kept well back, as this lessens the liability to injure the spine and lumbar muscles, and also reduces the tendency to struggle.
Care should be taken to fix the legs evenly; if one is tighter than the other an accident may happen. It is the details that matter, and a method that has proved successful should be continued. It occasionally happens that even with the greatest care an accident occurs: the horse may break a leg, injure the spine, or strain the lumbar muscles, and for this reason the standing method of castration has been largely resorted to.
Method of securing when Chloroform is given to the Horse Standing. Appliances. A strong head-stall or cavesson with long rope attached; a chloroform muzzle; double side-line.
The head-stall should fit tightly over the angle of the jaw, so that it cannot slip off, and should be placed higher up the nose than usual. The rope should be attached to the front of the nose-piece, and the other end run through a ring in the wall or round a post, the horse being held up close to the wall. The muzzle may then be applied and the anaesthetic given, or the side-line can be put on first.
The ropes should be above the hocks, and the two loose ends tied tightly over the withers.
When the animal becomes drowsy, reels in his gait, or shows a tendency to fall down, the ropes should be slipped down into the heels and the animal cast in the usual way. One man at each rope is usually sufficient, as there is practically no struggling. The man at the head gradually releases his rope, and when the animal is down holds the head and muzzle in position.
For castration it is only necessary to pull up the top hind leg and secure it, when the opera tion can be quickly and humanely performed.
The above method is one the author has found the most successful, but some practitioners allow the horse to walk round in a circle until he is sufficiently narcotized, and then is either pulled down with a rope round the hind heels, or is allowed to fall down.
Nelder's, Gibson's, or Roberts' muzzle is probably the best for the purpose.
Mr. Parker's Method. A very simple and effective method of casting an animal for castration or any operation in the region of the scrotum is that of Mr. J. H. Parker, M.R.C.V.S., Farringdon.
It lessens the risk of injuring the limbs or back to a minimum, and after twenty-five years the originator claims that he has"never had a colt hurt itself." A rope about 10 yards long is used, which is applied round the near fore pastern, then passed to the back of the near hind pastern from without to within, folded over the fixed part once and brought above the near knee under the neck to the off side.
Two men are usually sufficient to pull the colt down, with the help of a man at the tail and one at the head.
The free hind leg is then fixed in the ordinary way, by means of a rope attached to the pastern, passing over the withers, under the neck, and fastened to the fetlock again, the free end then being passed round the leg above the hock to expose the scrotum better, and is held by an assistant. The other rope is held at the back of the animal.
If a very strong horse has to be dealt with, the off hind leg may be roped before it is cast, the free end passing over the back and being pulled by an assistant in that position.
Miles' Method and modifications of it are used by many practitioners, and although rather complicated are very safe both for the animal and operator.
Two sets of ropes and hobbles are used, one consisting of four shackles to go round three pasterns and just below the knee of one fore leg with a long rope, which is looped round the other pastern and then run through the shackles. The other rope is put on in the same manner as the ordinary double side-line, except that instead of being both in the heels they are first placed above the hocks, and only one is let down into the heel just previous to casting, which is done chiefly by means of the shackle rope. When down, the shackles are removed in turn, and the side-lines used to secure the hind legs in a somewhat similar manner to that described before. The fore legs are fastened by knee bands.
If a colt is operated upon, the shackles are only removed from the uppermost hind leg, which is pulled forwards and fixed by the side line, the other three legs being fastened together by the shackle rope.
The leather hobbles now commonly used by most practitioners can be employed instead of the shackles, the side-lines being put above the hocks until the horse is cast, then slipped down into the heel, and the upper leg or legs released as in the preceding method.
Casting Hobbles. For older animals and for most operations these hobbles are most service able. There are several kinds, but most of them consist of four leather straps with buckles and two iron D's, one fitting into the other, through which a chain and rope passes. The hobbles fit round the pasterns, and the buckles allow them to be fitted to any size of horse.
The same precautions as for casting with ropes should be taken as mentioned on page 861. The procedure is as follows: The head should be secured by a bridle, blinkers, or blinds applied, and with some horses a short twitch tied to the bridle is advisable. A surcingle is put on, or instead, a rope is placed round the body, between the fore legs and over the withers, to pull the horse on to the side required.
If the horse is to be cast on the off side, the near fore leg is held up, the key hobble applied to it, and the chain attached by means of a screw. One man standing at each leg adjusts the hobble and quickly passes the rope through the D's in the following order: near hind, off hind, off fore, and near fore.
The legs are put as close as possible to each other; when at a given signal the near fore leg is let down, the man at the head pushes the horse back, the men on the hobble rope pull, and the assistant on the back rope or surcingle pulls the horse on to the off side, then quickly gets on to the neck of the animal, assisting the man at the head, who endeavours to keep the neck well extended. The legs being pulled up together as tightly as possible, a spring hook is put on the chain to prevent it slipping. The hobble rope should be held by one or two men to prevent struggling and injury to the heels and coronets.
If this method is quickly and carefully carried out there is little risk of accident. If, however, the horse is not pushed back, but allowed to fall forwards on to the neck or point of the shoulder, a fracture of one of the cervical vertebrae or humerus may result. Also if too forcibly pulled over on to the side a fractured rib or serious internal injury may be the consequence.
To prevent undue struggling the head may be pulled round to the shoulders, and attached to the surcingle by means of a rope fastened to the bridle or head-stall, or an extension apparatus may be applied forcibly to extend the head, by means of a rope attached to the surcingle behind and the poll strap of the head stall in front.
Cross Hobbles. In order to facilitate opera tions on the legs it is sometimes necessary to detach one or more legs from the hobbles. This is done by unclasping the buckle after previously securing the leg by means of cross hobbles. These are usually made of leather in two parts, one to buckle round the fore leg above the knee, and the other round the hind leg above the hock. The legs are then brought into position by buckling the two parts together. A strong cotton rope answers the purpose if put on in the form of a figure 8 round the two legs and fastened in the middle.
To fix the hind leg forwards for operations in the region of the thigh probably the best method is the following: A long rope made of strong webbing is attached to the hind pastern, brought between the fore legs, under the neck, over the withers, and fastened above the hock of the same leg, or passed round the leg and held by an assistant standing at the back of the horse.
It should be noted here that forcible extension of a limb or fixing with cross hobbles, etc., increases the liability to fracture during the struggles of the animal, and to obviate this a tourniquet may be tightly applied above the hock.
Operation Tables. Several of these have been invented both in this and other countries. They offer special advantages both to the operator' and the animal.
The reasons that militate against their general use are their expense and the fact that they are fixtures, the patient having to be brought to the table, which is not always convenient or possible.
Most of the tables consist of a large padded platform, to which the horse is fastened while in a vertical position, by means of several girths going round the body and neck, the legs being fixed with hobbles and the head by a strong head-stall.
The table works on a hinge, and is placed in a horizontal position for operations.
To release the horse the table is brought back again to its original position and the horse unfastened.
The table devised by Messrs. Dollar & Vinsot is the one most commonly used now.
It is 7 ft. 6 ins. long by 2 ft. 6 ins. wide by 8 ft. 6 ins. high, so does not occupy much space. It is made almost entirely of iron, and is very durable.
The advantages claimed for it are that it has abolished the dangers of breaking a horse's back or limbs when casting on a straw bed; its use causes no alarm, and a horse is secured with as little disturbance as when being harnessed to a vehicle. As compared with old methods the time consumed is only one-eighth to one-tenth; the machine is always ready for use, and the horse is put in and fastened in a few minutes.
The animal may remain standing, although, incapable of resistance, it may be rotated to either side and to any extent.
Owing to the absence of a straw bed and its attendant dust, and more particularly to the fact that the horse is lifted off its feet and returned to the standing position without any struggle, perfect antiseptic treatment can be carried out.
Unfortunately, however, the table is only suitable for some operations. The horse requires very careful and skilled fastening, and it is usually necessary to employ complete narcosis in order to get the necessary stability for operation.
Method of Casting on a Hard Floor in a Confined Space. It sometimes happens that an operation has to be carried out in a confined space, where the floor is too hard to allow a horse to be thrown, and where there is no operating table. The following procedure is quite useful: The horse is placed in slings provided with pulley blocks and endless chain, also with breast strap and breeching. A stout head-stall is put on, the rein being run through a ring in the wall and held by an assistant.
Casting hobbles are placed on the legs and the four feet brought up together and secured by the spring hook.
The slings are then lowered until the horse is resting on the ground, the head being also gradually released at the same time. The men holding the hobble rope can pull the horse to whichever side is required. In this way there is no danger of injuring the ribs by falling on the hard floor, but of course straw should be provided.
The Halter. Before completing these notes I feel constrained to describe exactly how a halter should be applied and fastened. This may seem superfluous to some, but from long experience among agricultural students and others, and especially considering the appalling misery and waste of horse flesh during the late war from want of this knowledge, I have come to the conclusion that to some, perhaps, it may be useful.
Method of Application. The halter should be loosened and the nose-piece held in the two hands while the horse is approached on the near side. The nose-piece is put over the nose, then the hands are slipped up the cheek pieces and the halter lifted over the ears and adjusted in the right position.
With unbroken animals it is sometimes best to put the halter over the ears first, and allow the nose-piece and shank to fall over the nose, or the rein is first slipped round the neck and held while the halter is put on.
A horse should never be led or tied up without first hitching the halter so that it cannot pull tight and injure the jaw.
I have known cases where horses have been tied up for days without being able to eat or drink, from neglect to carry out this simple precaution. In other cases, when the rope becomes tight the horse gets restive, runs back, and may injure himself, the vehicle, and the passenger.
There are several knots; the commonest one is tied round the shank under the jaw. This is objectionable, as it comes into contact with the sharp edge of the bone, and if left on long, may cause a large raw wound. Also it tends to get very tight, and in wet weather it is very difficult to untie. A better method is to fold it round both the nose- and cheek-pieces. The knot is then on the side of the cheek, never too tight, and never chafes the animal.
To fasten the horse the knot used should be one easily untied in case of emergency. If the slip knot is adopted, the ends should be put through the loop; if then the horse gets the end of the rope in his teeth he cannot pull it undone.
The army method is to form a clove hitch round the rail or ring.
A useful method of making a halter smaller is to seize the cheek-piece in the left hand, twist it round to form a loop through which the end of the rope is passed. This may be done several times if necessary until the right size is obtained.
Restraint of the Ox. The ox differs from the horse both in temperament and in its means of defence. Although a quiet attitude is always to be advised, especially in dealing with cows, yet it will be found that the intelligence of the ox is much inferior to that of the horse, and little can be done without fixing the animal in some way.
The chief weapons of defence or offence are the horns and hind legs, and the operator must guard against both.
It has to be remembered that a bovine animal can kick forwards and outwards,"cow kick,"while a horse usually only kicks back wards.
It is not often necessary to cast the ox, and most minor operations can be performed in the standing position; it is usually only required to secure the head, and the animal will remain quiet.
Securing the Head. The method will depend upon the size and temperament. If a bull or wild bullock has to be dealt with, it is best to throw a rope in the form of a noose over the horns or round the neck and run the other end round a post or through a ring in the wall. As the animal plunges forwards the rope is pulled and the head drawn tightly up to the post, where it is secured. The head should be fixed about one foot from the ground.
In the case of a quiet animal it is usually only necessary to grasp the horn with one hand and seize the nostrils with the other, firmly pressing the septum nasi between the thumb and fingers. This causes a certain amount of pain, and distracts the attention of the animal from the seat of operation. If the head is pulled round to the side and the operator presses his back well into the shoulder of the animal, a strong beast can be held for some time until the fingers get tired. To obviate this a nose clamp or bull-dogs may be applied to the nose.
There are several kinds: some in the form of tongs, the handles of which have to be held; others provided with a sliding keeper or screw which keeps it in position.
Probably the most useful design is one with a spring keeper and handle in the form of a ring. A rope can then be attached to the ring, and the head secured in whatever position is required. It is especially useful for raising the head for intra-tracheal injections. For this purpose the rope may be passed over a beam and held by an assistant. An ordinary rope can also be utilized. After being tied round the horns a loop is passed round the head between the eyes and the nostrils, or if it is required to drench the animal the loop is placed round the top jaw only, and the head raised either by passing the rope round a beam or by an attendant.
Bulls should always wear a ring in the nose; they can then be easily caught, and led about by means of a pole or rope with a spring hook attached. The advantage of a pole is that the bull cannot get too near the attendant.
A short chain is sometimes left on the ring in the case of vicious bulls, so that when they lower their head to charge they tread on the chain, which acts as a deterrent.
A very effective appliance was introduced by M. Vigan. It consists of a pole of sufficient length to reach from the withers to a point about one foot beyond the muzzle. A surcingle or rope is placed round the body, which passes through an iron staple at the end of the pole.
At the head end of the pole is an iron handle, while just over the nostrils is a hook which is inserted into the nose ring. A rope is passed round the horns and attached to the pole. By taking the handle in his hand the operator is able to raise or lower the head at will, and the most vicious animals are thus easily controlled.
Securing the Head and Tail. A simple method of securing animals for some operations is to fix the head as described previously, and then pass the tail through the slats of a gate or over the top of the stall and hold it securely in that position. The animal can then neither turn round nor lie down.
Administering Medicines. With quiet animals one man can usually secure the head by passing his arm over the nose in front of the horns, inserting his fingers into the corner of the mouth and lifting the head upwards, the drenching horn being manipulated with the other hand.
If two persons are required, one stands on the off side and holds the horns, while the other seizes the lower jaw, pushing it upwards, and administers the drench. If the animal is very restive the nose is seized with the fingers or nose clamp with one hand and the near horn with the other while the operator give. the medicine.
The preceding method is preferred by some, ae the head and neck are held then in a horizontal position, and there is less fear of choking the beast.
Securing the Fore Legs. This may be done by means of a rope round the heel, passed over the animal's back and held by an attendant, ce a knee - strap may be used similar to that described for the horse.
Securing the Hind Legs. It is unfortunately a common habit for cows to kick while being milked, or while the teats and udder are being manipulated, and there are several method: employed for preventing it.
(1) The simplest preventive is by means of passing the tail between the legs and round the hock, where it is held securely. When the cam lifts the leg to kick, the pull on the tail bring the weight on to that leg again, and so acts a: a deterrent.
(2) A rope is attached to the leg above the (b) It also may be secured against a wall by means of a rope attached in front to a ring or post, about the level of the elbow, and carried round the animal to a ring immediately behind on a level with the stifle. By pulling on the rope the animal is pressed against the wall.
To lift One Hind Leg. — It sometimes happens that cattle need attention to their hind feet, and it is no easy matter to secure the leg in the right position to use the knife. A good method is to place a round pole, e.g. a broom handle, in front of the hock of the leg to be lifted, and behind and above the opposite hock. The ends are lifted by two men upwards and backwards.
Another way is to fasten a rope to the fetlock and pass the loose end over a beam above and slightly behind the cow. The rope is pulled by an attend ant, the foot being seized fetlock on the milking side, and tied to a post or ring in the wall behind the cow.
(3) Hock Straps. A leather strap with a D and a buckle is used. It is first put round one hock, through the D, and then buckled round the other.
(4) A rope is looped round one hind leg above the hock and then passed backwards and forwards round the legs, forming a figure 8. It is tied in the middle between the legs, or if necessary after tying, the end is held by an assistant standing behind the animal.
(5) A rope with two loops is passed round the hock, and tightened up by means of a stick passed through the loops, after the manner of a tourniquet. This inhibits the use of the leg, but being painful is scarcely to be advised during milking.
Other methods which may be employed during operations on the under parts of the body are: (a) Place a round stout pole in front of the hind legs, one end resting on the ground, the other being held at the height of the body by an assistant. If the animal is placed against a wall and the head secured, it is unable to move far in any direction.
203.Method of restraint for injection.
at the same time by the operator, allowing it to rest on the knee after the manner of shoeing a horse.
Casffng. Casting the ox is comparatively an easy process compared with the horse, and is not attended by such great risks. It is rare for the ox to sustain a fracture of the limbs or vertebrae, but it sometimes happens that the horns are broken off during the struggles of the animal; also the rumen may be ruptured if too distended at the time of operation. The greatest danger is in casting the pregnant cow.
This should be avoided if possible, as abortion frequently results. In all cases a soft bed of straw should be provided, the animal should have the head controlled by a halter or rope round the horns, and a nose clamp, and it should have been fasted for at least twelve hours.
Casting for Castration. Very often calves are operated upon standing, but the operation is simplified and done in a more aseptic manner in the recumbent position.
A short rope with a loop in one end to fit the neck is thrown over the head—a halter opened out answers very well; the end is passed between the hind legs and back through the neck loop on the right side, brought over the back, and pulled by an assistant, while the head is seized by the lower jaw and twisted upwards and towards the right side by another assistant.
The calf quickly falls on the left side, a turn is made with the rope round the shank of the upper hind leg, exposing the seat of operation, and is held there.
Beuff's Method. In casting older animals, especially cows, Reuff's method, which may be called"the method of persuasion,"is to be advised.
A long rope is necessary. One end is fastened round the horns, then half-hitches are made respectively round the base of the neck, the chest, and flank, the free end being carried backwards over the hip. The head is held by, an assistant or fixed to a post, while two assistants apply traction to the rope, either from the right or left side according as it is required, to throw the animal on the right or left side. The body being gradually compressed by the rope, the ox in a few seconds quietly lies down, and will remain down as a rule, while the pull on the rope is maintained. It is best, however, in lengthy operations, to secure the legs by another rope or hobbles.
Double side - lines may also be used in a similar manner to that described for the horse. As, however, it is somewhat difficult to keep the ropes in the hind heels, and chafing often results, it is best to use small hobble straps round the heels, through the D's of which the ropes may be passed, or the hobble straps may be put above the fetlocks.
Another method is to fix the rope to the horns first, instead of passing it round the neck; the side-lines then go between the fore legs as before.
Hobbles. Small English casting hobbles are also very effective. The leather loops should then be placed above the fetlocks, otherwise the procedure is the same as for the horse.
Casting with Rope on Three Legs. This is a convenient method if the hobbles are not at hand.
A loop is made at one end which is placed round the near fore heel; the rope is then carried round the off fore pastern, from behind, forwards and inwards, thence round the off hind pastern, and back around the part of the rope connecting the fore legs. The rope is pulled backwards, and the three legs being drawn up together, the animal falls over and is secured.
It is sometimes necessary to roll the cow; e.g. to rectify torsion of the uterus.
The cow is cast by one of the preceding methods, preferably Reuff's. The legs are tied in pairs, one front and one hind around the shanks, and held in position by a rope attached to the legs and passing round the back of the animal. The cow thus secured can be rolled over repeatedly with little danger either to the animal or operator.
Not many dogs are naturally vicious, but occasionally they are met with, in certain breeds such as the chow, mastiff, Airedale, and bull terrier, and the operator can generally judge of this by the demeanour of the dog and the expression in the eyes.
Muzzles. It is always wise to secure the mouth, and there are various muzzles made for this purpose, some wholly of leather, and others of wire with a leather strap going round the neck. The leather muzzle is to be preferred, as it is lighter and more comfortable for the animal, and if used to prevent interference with an operation wound it is less likely to lacerate the parts.
Many muzzles are made to fit too closely over the nostrils, while leaving a large space between the lips, and it is often necessary to have another piece of leather sewn on in this position, especially when it is desired to prevent the dog from picking up garbage or from licking a wound.
Tape Muzzle. A very good muzzle can be made with a piece of tape or narrow bandage about 2 to 3 ft. long. It may be folded to form a clove-hitch, which will not slip, or simply tied round the nose with the knot under the jaw, the loose ends being brought round on each side of the head and tied securely at the back of the neck. As an extra precaution the ends may be then tied to the collar. For short-nosed dogs, such as the bulldog or pug, the ends can be brought down the middle of the skull and tied round the nose - piece, so relieving the pressure on the top of the nose, also ensuring that it does not slip off.
To make the clove-hitch two loops are made in the tape, the second one being placed behind the first.
It can very readily be removed by untying the knot and pulling one of the loose ends. If no tape or string is available, the dog is best held by grasping the skin at the back of the neck with one hand, while the other is held round the jaws, or below the bottom jaw, an FIG. 207. Dog catcher.
assistant grasping the two fore legs to prevent scratching.
Dog Catcher. If there should be any diffi culty in catching the dog, a"catcher"made of a long stout pole with an iron piece at one end, curved to fit the neck, and two eyelet holes to receive the rope. The rope should be a little longer than the pole, so that it may be passed loosely over the dog's neck, then pulled tight and the rope twisted round the pole. The dog is thus prevented from approaching the operator, and can be further secured at leisure. If the iron part of the catcher is sufficiently bent there is no fear of strangling the dog.
To administer medicine in the form of a pill, the top jaw should be grasped with the left hand, pressing gently the lip on the upper teeth, which induces the dog to open the mouth and also makes him disinclined to bite for fear of injuring his own lips. The pill is then administered with the right hand.
For this operation an assistant should firmly grasp the dog at the back of the neck with one hand and with the other press the dog's head upwards or hold the fore legs.
To administer liquids one hand should lightly hold the nose upwards, while the commissure of the lips is pulled out and the medicine gradually poured in, an assistant holding the dog as before. This is much better than attempting to pour liquid into the front of the mouth. The animal, fearing to be choked, struggles, usually spills the medicine, and may bite the operator.
Gags. To examine the mouth and throat, or for dental operations, various appliances have been invented. The gag suggested by Mr. Gray is very useful. It fits on to the canine teeth, is made with a bend in it to prevent it being pressed together, and has a spring which opens it, so keeping it in contact with the teeth.
It is best to apply a tape muzzle first to prevent the jaws being forced open too wide.
Another good gag is Hobday's, which consists of bars which are put in the mouth and strapped over the jaws. The mouth is opened by two screws, one on each side, separated by turning two nuts.
Messrs. Arnold also have invented one which works on the same principle as Gray's, and is very effective.
If no gag is available two pieces of tape may be placed in the mouth beyond the canine teeth, one being tied round the top jaw and one the bottom. The mouth can then be held open while an examination is made of the interior.
Operating Tables. In order to secure the dog for operation purposes it is necessary to strap him down to a table.
There are several specially prepared tables for this purpose, but as they are not always at hand, an ordinary kitchen table may be utilized.
Four double pieces of strong tape are folded to form a running loop, which is put round each leg above the hocks and wrists, and the ends tied to the legs of the table, or to hooks placed there for the purpose. The dog is then muzzled and stretched out, so that he lies fiat on the table.
Clamps to fix on the table with adjustable sliding cords attached are an improvement on the preceding method, as they can be placed anywhere on the edge of the table, and can be adjusted according to the size of the dog.
A table can be made from a strong board about 6 ft. by 3 ft. with a number of holes punched out to fit an ordinary key. It should be made of some strong hard wood, with cross pieces on the under surface to raise it high enough to allow a key to be put through from above.
To render it easily cleaned it should be painted with enamel. It can then be placed on another table or on trestles.
Hobbles are made of strong webbing or strips of raw hide, and attached to the keys. The front legs are secured first, and then the hind ones are stretched backwards as far as they will go, but not unduly to strain the animal, an attendant at the same time holding the dog and pressing gently on the back. The dog may be placed on its back or abdomen, and the legs may be fixed in whatever position is most suitable for the operation.
It is a good plan also with a large strong dog to tie a rope completely round the dog and table. To lessen the excitement, straining, and fright, it is often advisable to administer a dose of morphia hypodermically about an hour before the operation; there is then no difficulty in securing the animal, and if a general has to be given, e.g. chloroform, the is considerably aided.
For vicious dogs morphia is a very great boon, even for minor operations.
Of the special operating tables probably those suggested by Livon and by Hobday are the most useful. Hobday's is made of metal, is about 52 by 22 ft., and provided with stout trestles to render it stable during operations.
It has the great advantage of being easily moved about and sterilized.
Another form of table is made in the shape of a trough. This allows the fluids to be easily drained off, which is an advantage during some operations, and it also prevents too much lateral movement. Macqueen, Bernard, and Young have suggested various modifications of this table.
After operations have been performed it is very difficult to keep our patients quiet, and to prevent them scratching the wounds. When ever there is irritation, the dog wants to scratch or rub the part, especially if it is in the region of the head.
A broad collar made of tin or leather, called an Elizabethan collar, may be usefully em ployed. It is made in several sizes to fit the neck, and prevents the dog turning his head.
Stiff cardboard or leather may be cut out to enclose the neck, and holes made along the two edges, through which a tape is laced. If this is put on tightly it stops much lateral movement.
Sometimes, however, it is necessary to put the animal in a bag, the mouth of which should be tied round the neck of the patient.
To prevent scratching with the legs, a tape may be tied round the fore or hind legs just above the feet. There is just sufficient room for the dog to walk, but not to allow him to put one leg on the ground and scratch with the other.
The Cat. Although the domesticated cat is a gentle enough animal when unmolested, yet one has not to proceed very far with any method of restraint to realize that it is not very far removed from the wild state, and that it is essentially a feline animal, strong, agile, resourceful, and possessed of very adequate means of defence.
Bites or scratches from cats are dangerous, as the wounds inflicted are usually deep, and owing to their habit of scratching in garden earth, tetanus has been known to result. It therefore behoves every operator to protect himself in every possible way.
To secure the claws a -strong square towel or cloth should be placed on a table, the cat lifted upon it, and the ends tied tightly cross wise over the back. The head can then be firmly grasped with the left hand and pulled upwards while medicine, etc., is being adminis tered.
Another method is to roll the cat several times in a strong cloth, leaving out the head, but bringing the cloth tightly round the neck, where it is held securely.
For operations upon the back parts, such as castration, the cat may be held by an assistant in the following manner: With the cat resting on a flat surface the hind legs are seized above the hocks between the third and fourth fingers of each hand, the fore legs between the second and third fingers, leaving the thumbs and first fingers to grasp the head above and below. The cat is then lifted up into a convenient position for operation.
This method needs some skill, pluck, and strong fingers, but is by far the best way of holding a cat for castration.
From time immemorial a jack-boot has been utilized, the cat being placed head first into the boot, while the tail is seized and held firmly by an assistant. There is, however, a good deal of struggling, and this method is not com mendable.
Some operators roll the cat in a cloth, the head being also included, but the back parts exposed. There is some danger of suffocation by this method if the operation is delayed, but it is very effective.
Several different kinds of tables and hobbles have been invented by means of which the cat can be strapped down.
Hobday's operating table answers admirably, the cat being secured in the same way as described for the dog, care being taken that the tapes are drawn very tightly round the legs, just above the paws in the fore legs, and above the hocks in the hind limbs.
Failing a special table an ordinary kitchen table can be utilized, and the cat's legs tied by means of tapes to the legs of the table.
Mr. Gray has suggested a very useful rack, made of two iron bars with clamps at each end, to fix to the edge of the table. The cat is then stretched out between the bars, to which it is secured by tape hobbles.
Securing the Pig. Aged boars and sows are sometimes vicious, and care has to be taken in approaching them, but this is the exception.
In all cases pigs should be driven into a confined space, and the operator should be provided with a wooden tray about two to three feet in breadth and about two yards long, which can be placed in front of the person to act as a shield, and also to drive the pig into a corner and secure him against the wall; there is not then much difficulty in catching the animal.
With small pigs it is usual to catch hold of one hind leg or the ears. If an operation such as castration has to be performed, the head is placed between the legs of an assistant and the two hind legs are held upwards, one in each hand, wide apart, which exposes the scrotum in a convenient position for the operator.
The operator, on the other hand, may choose to hold the pig's head between his own knees, while the assistant seizes the hind legs. In either case care should be taken not to squeeze the chest too hard, otherwise death may result.
To catch larger pigs, a running noose may be skilfully dropped over the top jaw, taking care that the rope is placed beyond the tusks, or it will slip off. This is pulled up tight, and the loose end passed round a post. The pig hangs back, so tightens the rope, and can then be further secured if required.
Another method is to take a stiff piece of cord attached to a stick with a running loop, in which some solid food is placed. When the animal opens its mouth to take the food, the noose is slipped over the snout and the pig secured.
A crook similar to that used for the sheep can be utilized, or a mechanical hog-catcher with jaws, attached to a pole and operated by a rope, can be used to seize one of the hind legs. To secure the Head. — A twitch may be applied, similar to the one employed for the horse. This is passed over the upper jaw, or round both jaws, and tightened sufficiently to prevent it coming off.
A device called the Champion Hog Holder is very useful. It is made entirely of metal, has a loop slightly bent at one end, which goes into the mouth, fitting over the top jaw, and a handle at the other end. One man can easily restrain the largest boar by depressing the holder, and so squeezing the nose.
To administer a Drench. This is always a risky operation in the case of a pig, but when it is necessary the animal should be seized by the ears by an assistant, who stands with his back to a wall with one leg on each side of the animal, and if not too heavy lifts its fore legs off the ground. An old boot with a hole cut in the toe is then put in its mouth, and the medicine poured slowly into the top of the boot.
To cast a Hog. One man holds the ears, while another reaches over the back, seizes the hind leg, and by a combined effort the animal is thrown on its side, where it can be secured by tying its legs together by means of a soft rope around the shanks, an assistant pressing his knee on its neck.
Securing the Sheep.It will not be necessary to describe in detail methods of restraining the sheep, as it is easily controlled and has no effective methods of defence.
It is usually sufficient to seize it round the neck with the left arm, and with the right hand grasping the hind leg or the wool of the flank"turn it"on to its buttocks. The sheep being propped up between the legs of the shepherd, can be given medicine or operated upon without much difficulty.
The sheep may also be turned on its side, and held down by a little pressure on its neck, or the legs may be secured by tying the limbs in pairs, the cannon bones of the front and hind legs on each side being placed parallel to each other, and secured in that position by a soft rope.
Castration. For this operation the shepherd seizes one hind leg above the hock in each hand, and lifts the lamb with its back pressing against his chest; the parts are then exposed, and the operation quickly performed.
Stocks. A very simple and effective means of securing a sheep in the standing position for"trimming,"paring the feet, or dressing the skin, is by means of stocks. This is easily made from a stout piece of soft wood, cut in the shape of a fork at the top of sufficient size to admit the neck of a sheep. Holes arc made on each side of the forked piece through which an iron peg is passed to secure the head. The bottom of the appliance is sharpened so that it can be driven into the ground. It can thus be taken about by the shepherd and used wherever the sheep may be.
For obstetric work a raised table made out of hurdles is most useful, and should always be at hand during lambing time. The sheep is held by an assistant, and can either be placed on its back or sides, according to the position required. There is then much less risk of septic infection, and the work of the obstetrician is made comparatively easy.
Anesthesia, in the broad sense of the term, is"suspension of sensation,"whether due to disease or injury or brought about for surgical purposes by various agents called anesthetics.
The chief objects of anesthetics in surgery are the abolition of pain during operations, the prevention of various reflex movements, and the production of muscular relaxation.
Anesthetics may be either local or general, the former acting only on the part to which they are applied, and the latter acting on the central nervous system and causing complete loss of sensibility. The production of local anesthesia is thus indicated for surgical opera tions on limited areas, and also when it is considered dangerous to produce general anes thesia on account of some defective condition of the patient. General anesthesia is indicated in the more serious or major operations involv ing larger areas or body cavities, to relax muscles in the reduction of herniae and luxa tions, for the setting of fractures, and in bad cases of dystocia; also, in the case of the dog particularly, to cause relaxation of the abdo minal muscles to facilitate the examination of the abdominal contents for diagnostic purposes.
Local Anaesthesia.Local anesthesia can be brought about by various means. The old methods consisted of the compression of nerve trunks and the application of cold. The former was brought about by the use of the tourniquet, an agent now rarely used for that purpose, although still of great service in the practice of hemostasis during operations on the limbs. The application of cold was accomplished by a mixture of equal parts of pounded ice and common salt in a muslin bag and kept on the part for five or ten minutes until it was practi cally frozen. This method was superseded by the use of a spray of anhydrous ether or of ethyl chloride to freeze the part by rapid evapo ration. These methods are rarely advocated now, as both the freezing and thawing processes are more or less painful, and if the part is too well frozen the healing process may be con siderably retarded.
The local anesthetics now employed are various chemical agents which produce paralysis of the peripheral endings of sensory nerves. They include cocaine, eucaine, holocaine, novo cain (kerocain), stovaine, acoine, tropacocaine, and hydrochloride of urea and quinine. These may be used singly or in combination, either by painting on to the surface, or by injecting into or round the part to be anesthetized, or by injecting over the trunk of the nerve supplying the part. Excellent advantage can be taken of this latter method in anesthetizing the foot of the horse both for operations within the hoof, where for obvious reasons the local anesthetic cannot be directly injected into the tissues, and also for assisting in the diagnosis of the seat of obscure lameness by the process of exclusion. In such cases the anesthetic may be injected over the plantar nerves above the fetlock joint.
Cocaine.Cocaine was the first chemical agent used in the production of effective local anesthesia. The pure alkaloid cocaine is very sparingly soluble in water, but its salt, the hydrochloride of cocaine, is freely soluble in water and alcohol, and, being equally effica cious, is employed. When a 5 per cent solution of cocaine hydrochloride is applied to a mucous membrane or injected into the cutaneous or subcutaneous tissues, the first noticeable effect is pallor due to vascular contraction occurring in about one minute; two or three minutes later the part has become insensible to pain and touch owing to paralysis of the sensory nerves of the part. This is due to a direct affinity on the part of the cocaine for the cell protoplasm, especially of the sensory nerve endings. This affinity for protoplasm should be well remembered when deciding upon the strength of the solution to be employed. The writer has frequently observed that when more concentrated solutions than 5 per cent are infil trated into operation areas, the healing of the operation wound is very materially retarded. The affinity of the cocaine in those strong solu tions is such that it actually becomes a cell poison, and either markedly reduces the vitality of the cells or even destroys it, and healing by"first intention"is rendered impossible. The writer, therefore, in the light of further experi ence, prefers to employ for infiltration anes thesia larger quantities of weaker solutions and injected at a series of points round the operation area, rather than a smaller amount of a stronger solution injected directly into the site of opera tion, a view contrary to one which he expressed several years ago when writing on the same subject. For injection into the tissues, 1 per cent to 4 per cent solutions are to be preferred to the stronger solutions, though the latter, from 5 per cent to 10 per cent, may be employed over a nerve trunk to produce conduction anesthesia of a part below. In such cases the cells of the part directly exposed to the cocaine are not further mutilated by the operation incision, and the ill-effects are not so likely to occur; moreover, the anesthetization of the remote parts is more likely to be complete. When injected under the skin the area anes thetized extends over a radius of about an inch round the point of the needle. The insensibility occurs in from three to five minutes and lasts from twenty to thirty minutes.
Dosage. The amount of cocaine that can be injected with safety and without causing muscular spasms likely to interfere with opera tion varies with the idiosyncrasy of the patient. In the small or so-called toy dogs one-tenth of a grain (i.e. 10 minims of 1 per cent solution) for each pound body-weight is usually quite safe. In larger dogs the same proportion may be employed, but in any given case 2 grains (40 minims of 5 per cent solution or 100 minims of 2 per cent solution) must be regarded as the maximum amount. In the cat the same pro portion may be employed, but of a grain must be regarded as the maximum safe dose.
In the horse the maximum dose is 10 grains, an amount which is rarely required. Some horses are much more susceptible than others, and I have seen great excitant toxic effects follow the hypodermic injection of 2 drachms of a 5 per cent solution (containing about 6 grains of cocaine). Two grains in 40 minims of water injected over each plantar nerve will completely anaesthetize a horse's foot.
For cattle, cocaine may be used as for horses, but is much less frequently employed. It is very useful for the eye in cases of chaff under the eyelids, allowing the foreign body to be removed quite painlessly; and in the operation for carcinoma of the orbit and tumours else where.
The local ansthetic action of cocaine is much improved by combining with it solutions of suprarenal extracts as adrenalin, or its synthetic substitutes suprarenin, adnephrin, and renastyptin. These agents cause a contraction of the vessels at and round the seat of injection, rendering the part anmmic, and reducing the local circulation. Consequently, the absorption of the cocaine into the general system is re tarded and the local ansthetic action is ren dered more complete and more prolonged. Less cocaine is necessary and the danger of poisoning is thus reduced in both ways. The operation is further facilitated by being almost bloodless. The amount employed is from 5 to 10 minims of 1 in 1000 solution for dogs, and up to 1 drachm of a similar solution for horses.
When small doses of cocaine are absorbed into the general circulation the effect is to act as a restorative and general stimulant of the central nervous system, and is consequently a very useful agent for producing local anaesthesia and minimizing surgical shock in weak animals, especially dogs, when general anesthesia is regarded as dangerous.
When too large doses of cocaine are injected toxic symptoms are set up. A few minutes after the injection in such cases the patient begins to lick his lips and salivate, the eyes become dilated, and visual accommodation is interfered with, excitement and hypermsthesia are produced, the ears are moved rapidly back wards and forwards, and there are well-marked muscular twitchings or clonic spasms and inter ference with co-ordination' of movement, while horses paw the ground and are often difficult to control. This state of affairs, and parti cularly the muscular spasms, obviously defeat the object of the administration of the cocaine, and it is impossible to proceed with the.operation until the symptoms subside, which may be several hours later. In the smaller animals it may prove fatal by paralysing vital nerve centres and causing syncope or asphyxia. If one wanted to be certain of killing a dog by cocaine, however, it would be necessary to inject from 5 to 8 grains, according to size, which would be fatal in about half an hour, while from 2 to 3 drachms is necessary to be certain of killing a horse. The best antidotal treatment in susceptible animals appears to be the administration of either morphia or caffeine hypodermically, or a good dose of strong coffee, together with perfect quietness.
Owing to the toxicity of cocaine a number of very useful synthetic substitutes have been introduced, their chief recommendation being that they can be used with much greater safety in the smaller and more susceptible animals.
These agents include novocain, beta-eucaine hydrochloride, hydrochloride of urea and qui nine, stovaine, holocaine, tropacocaine, acoine, and others.
The writer has had considerable experience with most of them and does not recollect having any untoward results from any of them, using them in precisely the same manner as cocaine. They have each certain advantages over cocaine, and, as with that agent, their effect is improved by a combination with a haemostatic.
Novocain, and its English equivalent kero cain (Kerfoot's novocain), is a non-irritant local ansthetic freely soluble in water and may be sterilized by boiling. It may be used in similar strengths (2 per cent to 5 per cent solutions) as cocaine, and in larger quantities without the danger of producing toxic effects. The writer considers novocain and kerocain to be about the best of the local armsthetics.
Hydrochloride of is also a very good local anaesthetic. Compared with cocaine, it is less toxic, its action is slower in commencing, but is more prolonged. It can also be sterilized by boiling. It is often advantageous to com bine cocaine and eucaine in order to obtain the quicker action of the former and the more pro longed action of the latter. When combined the solution should only contain half the per centage of each ingredient.
Hydrochloride of urea and quinine is probably the least toxic of all the local anaesthetics. It is effective in solutions of 1 per cent to 5 per cent, and can be used on quite young animals with perfect safety. It is also very cheap. It is, however, very slow in bringing about ans thesia and requires to be injected about thirty minutes before operating; while, on the other hand, its effects are very prolonged, extending in many cases even up to twenty-four hours. The advantage of this is very obvious in many veterinary patients, as it reduces the tendency of the animal to interfere with an operation wound during, at any rate, the first day. It does not appear to possess any effective haemo static property and may be combined with adrenalin with advantage. I have amputated digits in dogs, and excised tumours in dogs and horses in comfort without any indication of pain in nervous animals that have objected strongly to the primary introduction of the hypodermic needle.
Spinal Anmsthesia.Intraspinal injections of sterilized local introduced in the lumbar region may be used to produce ans thesia in the posterior part of the body and the hind limbs. For this method stovaine is usually preferred to cocaine, owing to its lower toxicity and its less depressant action on the heart. Under this anesthetic quite serious operations in the human subject can be performed pain lessly in patients for whom general anaesthesia would be dangerous. Macqueen, in Veterinary Medicines (Finlay Dun), says:"The injection is made through the lumbo-sacral space at the point of intersection of two lines, one median uniting the last lumbar and first sacral verte brae, the other transverse connecting the summits of the internal angles of the haunch."The entrance of the needle into the subdural space is indicated by the escape of cerebrospinal fluid. This method is not in favour in veterinary practice, since equally advantageous results in the smaller animals may be obtained by other means much less dangerous, such as the appli cation of a local ansthetic in combination with the administration of a full dose of morphia half an hour or an hour previously. The chief objections are the uncertainty of absolute asepsis, the difficulty of injecting the anaesthetic into the proper place and without injury to the spinal cord, and the serious nature of the com plications if they should arise in this particular situation. In the larger animals, moreover, the distance of the spinal canal from the skin renders the injection still more difficult. A detailed description by Merillat of the method as applied to dogs is reproduced in Ancesthesia and Narcosis of Animals (Hobday).
General Anwsthesia.As already indicated, general anaesthesia implies a temporary complete suspension of consciousness and of sensation. The writer would differentiate it from narcosis, in that in the case of the latter the loss of con sciousness is not complete; an animal can be wakened up by such things as a loud noise or a smack, only to fall off to sleep again without the administration of any further agent; the narcosis is more tardy in being produced, and is much more prolonged. The effect of a general anaesthetic is more rapidly induced, more com plete, but more transient. A patient regaining consciousness or awakening from a general ansthetic does not again lapse into uncon sciousness without further administration of the ansthetic. The difference between the effects of morphia and chloroform well illustrates the point.
The method of induction of general ans thesia is by inhalation, and the principal agents employed include nitrous oxide, chloroform, ether, and mixtures of alcohol, chloroform, and ether, such as A.C.E. mixture (alcohol 1 part, chloroform 2 parts, ether 3 parts) and A.E.0 mixture (alcohol 1 part, ether 2 parts, chloro form 3 parts). Of these chloroform is the most effectual and, if properly administered in veter inary practice, it is a very safe anaesthetic. Proper administration includes the preparation and the preliminary examination of the patient as to the condition of the heart and lungs in particular. If the heart is weak, irregular, or intermittent the administration of chloroform for anaesthesia is decidedly dangerous. The same applies when there is fluid in the chest and, to a smaller degree, in cases of destructive lung disease, such as consolidation or extensive emphysema.
Preparation of Patients for Chloroform Ances thesia. The horse is an excellent subject for chloroform and requires but little preparation. Except in the cases of urgent operations it is well to keep the patient on a laxative and somewhat restricted diet for a day or two, completely withholding long hay or bulky food the night before, a muzzle being put on to prevent him eating his bedding. On the morning of the operation he may have a limited allowance of water and a small feed, such as a bran mash.
In cattle and swine the preparation is similar. Both species are quite good subjects.
Adult robust dogs are good subjects for chloroform if administered with care. Very young and very fat dogs are bad subjects. Especial care must be taken with the toy breeds and the short-nosed varieties, as bull dogs and pugs. The food should be diminished the day before, and only a light meal given on the morning of the operation, and not within two or three hours of the operation.
Adult cats are good subjects for chloroform if plenty of air is allowed, but ether and A.C.E. mixture are usually safer.
Administration of Chloroform Before administering chloroform, a supply of antidotes should be procured and ready to hand in case of necessity. They should include hydrocyanic acid, strong solution of ammonia, amyl nitrite, solution of strychnine, and adren alin.
Horses and Cattle. For the administration of chloroform vapour a muzzle or inhaler is neces sary, and there are several varieties commonly used.
(a) The simplest one is known as Cox's inhaler. It consists of a cylinder of leather or canvas, which fits on the upper jaw only, passing in the mouth to the commissures of the lips. It possesses a running string round the top, so that it can be drawn tightly round the nose to prevent or _ reduce the ingress _211. Chloroform muzzle. of air. It is held (Cox's pattern.) in position by a strap which passes over the poll. The chloroform is poured on to a sponge previously squeezed out with hot water to facilitate volatilization, and is inserted into the free end of the cylinder, which is then closed with a towel to limit the ingress of air. The nos trils should be first smeared with lard to prevent the chloroform blistering the skin, unless the muzzle is made with a wire or string netting across its in terior to pre vent the sponge coming into contact with the nostrils.
(b) Carlisle's chloroform muzzle is a very good one, but in the writer's experience not quite so safe as the former, as it may exclude too much air and cause asphyxia. It fits closely round the nose and mouth by means of a small bolster, while the other end is quite closed, except for a slot into which fits a tray with a sponge guarded by a wire netting. The chloroform is poured on to the sponge and the tray inserted, and then the end is completely closed by means of a leather flap.
(c) Roberts's muzzle, as used by the late Mr. Richard Roberts for the administration of chloroform in the standing position. It con sists of a leather cone, fitting tightly over the lower end of the face by means of a bolster and strap. At the lower end of the cone is a hole into which fits a fairly large cork or bung. The chloroform is poured on to a sponge loose inside the mask and the cork inserted. More chloroform is inserted as necessary by the removal of the bung. It appears to me that by this method and the Carlisle method the result is attained by partial asphyxiation, a course open to grave objections from the humanitarian standpoint, and causing great distress to the patient in the early stages of the procedure.
(d) The muzzle introduced by Mr. Nelder of Exeter appeals to me as being the best of all. It consists of two portions; the one placed first over the lower end of the face is cylindroid and made of tarpaulin, and to its upper border is fitted a bolster, which can be drawn tight and so prevent the entrance of air from above. It is fastened over the poll by means of a strap. The lower end is closed by a disc of leather much perforated, through which respiration takes place. A deep leather cap is made to fit over this, and is held to the former portion by straps and buckles. It holds a circular piece of felt or a sponge on to which the chloroform is poured, and when in position this is held FIG. 212. Chloroform muzzle. (Carlisle's pattern.) against the perforated disc of the muzzle. All air passes between the two portions and over or through the sponge, and the amount of air is regulated by the closeness or otherwise of the outer portion to the inner by tightening the buckles or relaxing them. In no case should it be drawn quite tight, since partial asphyxiation should be avoided. I consider this to be the best chloroform muzzle for a horse for administration either standing or in the recumbent position.
(e) A modification of Junker's method has been applied by Sheather, Hoare, and others to the horse. It consists of driving air by means of a foot-bellows through chloroform in a flask and on into the mask applied to the face. This is probably the most scientific method, for in this way the amount of chloroform vapour being inhaled can be most easily controlled. It is, however, by far the most laborious method, and since the horse is such an excellent subject, such a nicety of concentration or dilution of the chloroform appears to be quite unnecessary, and, taken as a whole, the method is not as satisfactory as some of the others. I have also seen a horse asphyxiated by this method.
Horses and cattle are usually cast with hobbles for the administration of chloroform, and all undue pressure on the throat and chest must be avoided. In each case the head must be kept fully extended during the administration of the anesthetic. ' The objects of this pre caution arc in the first place to permit of free respiration, and in the second place to reduce the power of the patient when attempting to struggle in the excitement stages and causing such severe injuries as fracture of the spine or one of the limbs. The amount of chloroform to commence with must depend upon the size of the patient, and varies from 3ss. to 3i. in the larger breeds. This quantity should be poured on to the sponge and inserted into the muzzle, and the end of the muzzle closed in order to limit the amount of air admitted. Further amounts of iii. to 3iii. at a time should be applied to the sponge as required. With good subjects, if the chloroform is administered without waste, to iss. is sufficient to thetize the horse in about ten minutes, and a total of will keep him well under for half an hour or so. By cautious administration, however, a horse may be kept sufficiently under chloroform for several hours. In England it is a common practice to exclude air as far as possible in order to expedite the anaesthesia. The writer, however, does not entirely agree with the practice. He admits that anaesthesia is more quickly obtained by this means and that it is more economical of chloroform, but it is at the expense of partial asphyxia. He prefers to allow more air and to use more chloroform.
He considers this procedure safer, and is of opinion that horses recover more quickly from the effects of the anesthetic. Some horses appear to be very resistant and practically immune to the anesthetizing action of chloro form, and the writer has met with cases in which 3xiv. and 3xvi. respectively were administered without producing anesthesia.
The Administration of Chloroform standing. Chloroform may be administered to horses in the standing position if there is plenty of room. This method has some advantages over the method of administration in the recumbent position, and may be advocated in the case of very refractory horses that are difficult to cast, and also in the case of some old horses with anchylosis of the spine, whose back might be injured if cast in the usual way. The injury to the back, however, is usually due to violent muscular contractions while under restraint, and is rarely or never brought about by the act of casting. If properly administered by this method many horses submit very quietly to the process, but others become somewhat violent, rearing and plunging, and may even fall over backwards. If done in a large loose-box or operating theatre the horse may also get down in a corner in a very awkward position.
The best method of procedure consists in putting on a strong head-stall or caveson and then placing the chloroform muzzle on the horse's head while in his loose-box. As he can breathe freely through it he does not seriously object. The animal is then led out into the paddock or operating yard and the chloroform, from hiss. to iii. according to the size of the horse, is poured over the sponge, or felt in the case of Nelder's muzzle. The end of the muzzle is then closed. The patient may be kept moving in a circle, but should be allowed to do so more or less voluntarily and should not be unduly restrained, otherwise he is likely to show fight. Nelder frequently administers 3i. of chloroform while the patient is still free in his stable before being brought out, and an additional when the horse is brought out. It is sometimes an advantage to strap up one fore-leg in order more easily to control the movements of the horse. In a good subject, in about five to ten minutes the patient sways a little from side to side, staggers a little, and either gently falls down or may be pushed over. When the horse goes down the stage of excitement is over, and as a rule it takes very little more chloroform to render anesthesia complete. The hobbles can then be placed on the horse quite easily, although if the anesthetic is continued it may be unneces sary to resort to this restraint, depending upon the operation about to be performed.
For chloroforming horses in the standing position in a little space, Male secures the horse by means of a caveson and a long rope, which is passed twice through a ring in the wall about the height of the horse's head. An attendant holds the rope firmly, well out of the horse's reach in case he should fight. 11 - A In such a case, however, the ..) horse soon realizes the .. - ) futility of struggling, and as ) in the other method of ministration standing, he I 13. I soon goes down or can be easily pushed over. Since t — ..t i', the rope passing through ,- ____ ii 4. - - 4,'L 0 the ring is not tight it can il 1' 1 I '' 11 , be quite easily relaxed or - 1, i released if and when necesit vill sary. Male sometimes ap lit - - io h 1. plies the casting side-lines to 4 _ 1,,,il, the horse with 11 — ILI, 1 the rope above , 0 the hocks before administering Fie. 214. Chloroform the chloroform, drop-bottle.
so thatwhen the horse goes down he can be quickly secured. (See"Restraint.") Dogs and Cats. Chloroform is best adminis tered to dogs stretched in a prone position on the operating table; collars should be removed.
The simplest apparatus consists of an ordinary wire muzzle and over it a towel, which should be only one layer thick, and to which the chloroform is applied by means of a drop bottle. This method is only safe for large anc adult dogs, care being taken to allow plenty 01 air, and not to be too free with the chloroform.
Another very simple and effective method is to pour chloroform on to a piece of lint or woo contained in a chip-box or galley-pot and helc over the nose. By this method there is ar unlimited supply of air, and although it haE the appearance of a rough-and-ready method it has much to recommend it.
Junker's apparatus is good for strong anc large dogs. It consists of a cone-shaped mast with an open apex. This is placed on the face and by means of a pump or bellows air is driver through chloroform in a bottle and, thug saturated, is passed on into the muzzle. Or passing through the bottle the air takes up about 2 per cent of chloroform. By means of one's hand at the open apex the amount of fresh air may be regulated and further dilution permitted, or otherwise.
Hobday has introduced two modifications of Junker's method, both leading to much greater safety for smaller dogs and for cats. By one method air is driven by means of a double rubber bellows over chloroform and on into the mask. By the other method the pump is placed between the flask containing the chloro form and the mask, and air is drawn over the chloroform and passed on into the mask. This latter method is the safest for very small dogs and for cats, as the chloroform vapour is so very dilute (1: 1000 to 1: 5000), so much so that the method is useless for larger dogs and must be supplemented with additional chloro form on wool placed in the mouth of the mask. The pump is of rubber, and has an elastic reser voir and a stop-tap at the mask to regulate the flow and to get a continuous current of air and chloroform vapour. The manipulation of the pump is rather fatiguing in prolonged operations, and to overcome this objection Hobday intro duced a small portable electrical apparatus to pump air over the chloroform.
The secret of success, by whatever method chloroform is administered, is the slow but con tinuous administration and the removal of all restraint to free and easy breathing.
Symptoms of Chloroform Anaesthesia.The effect of the inhalation of chloroform vapour can be observed as occurring in four stages, namely: (1) the excitant; (2) the narcotic; (3) the anaesthetic; and (4) the paralytic stage.
In the excitant or stimulant stage the first effect is a vigorous struggle of alarm, and that is quickly followed by excitation of the cerebral and cardiac functions. The pupil becomes dilated, the pulse and respiration are acceler ated, and faeces and urine are often passed. Vomition, even in the dog and cat, is very rare.
This stage may last from one to five minutes, but it is markedly shortened if the patient has previously received morphia hypodermically, or chloral hydrate by the mouth. It is not entirely without danger, especially in cases of cardiac affection, as the excitement may cause arrest of the heart's action, and attempts at restoration are rarely effective. Another danger is that in some cases where the chloroform has been administered in a too concentrated form the respiratory centre may be over-stimulated, and respiration may suddenly cease even before the patient has reached the stage. In patients with a normal heart, however, this first stage gradually merges into the second or narcotic stage. In this stage, generally reached within five minutes, there is great depression of the motor centres and the voluntary muscles become relaxed, commencing at the hind limbs. In the recumbent horse struggling ceases and the tail becomes relaxed. If administered standing, the horse becomes unable to support himself, staggers and falls gently, or is easily pushed over. In the dog and cat secured in the prone position the head sinks to the table and there is often a slight whimpering as though the dog were dreaming. In each case the reflex functions are only dulled, and sensibility is not completely lost. This is a useful stage for con trolling labour pains in cases of difficult par turition in both large and small patients, and also for minor operations. In the third, or ancesthetic stage, there is complete muscular relaxation and complete loss of consciousness. Reflexes are lost entirely, pupils slightly con tracted. The pulse and respiration become slower, even and regular. This is thetrue surgical stage, and if the chloroform is continued very slowly it can be maintained for an hour or two with perfect safety, since none of the vital nerve centres of the medulla, such as those controlling respiration and the action of the heart, are seriously affected. If, however, the chloroform be administered at this stage either copiously or with very limited admission of air, then a dangerous paralytic stage is produced owing to the medullary centres becoming in volved. The pupils become widely dilated, while the respiration becomes shallower and stertorous, irregular and jerky, and may sud denly cease. The pulse gets slower and weaker, but the heart may continue to beat several minutes after respiration has ceased. In such cases, if the chloroform is quickly stopped and plenty of fresh air admitted, respiratory stimu lants and artificial respiration resorted to, breathing is generally resumed. In some cases, however, if the chloroform has been pushed too far, the respiration cannot be restored, and death occurs from asphyxia. In other cases the heart's action may cease simultaneously with or even before the respiration, and in my experience such cases have resisted all restora tives and have always proved fatal.
In the Hyderabad experiments of 1888-9 it was clearly demonstrated that when lethal doses of chloroform were administered to healthy animals respiratory arrest always occurred from two to six minutes before cardiac arrest. This confirmed what was previously taught by Simpson, that the careful observation of respira tion is of paramount importance for safety in chloroform anaesthesia. Consequently anything with a tendency to impede respiratory functions must be studiously avoided, as already indi cated. The anaesthetist must see that the anaesthetic is being admitted slowly and regu larly, and he must keep a watchful eye on the character of the respirations. He should not concern himself with the work of the surgeon, however interesting it may be, for the chloro form must be withdrawn at the first indication of danger. The anaesthetist must remember that the work of the surgeon, however skilful, is of no avail if the patient should succumb to the anaesthetic.
The signs of danger may be summed up shortly thus: Shallow spasmodic or jerky breath ing, stertor, cessation of respiration, intermittent pulse, and widely dilated pupils. In the dog and cat also the coat may be seen standing up and even turning the wrong way.
Antidotal or Restorative Treatment.At the first indication of danger the chloroform should be stopped and the inhaler removed, together with all obstructions to free respiration. The tongue should be pulled forward in the mouth, and mucus and saliva mopped out. Remove hobbles and admit plenty of fresh air, or even oxygen if at hand. Then administer as quickly as possible a full medicinal dose of hydrocyanic acid (of 2 per cent or B.P. solution for horses, 3i., and for dogs and cats 2 to 5 minims). It may be dropped on to the dorsum of the tongue or injected hypodermically. It acts as a powerful and rapid, though tran sient, stimulant to the respira tory centres, and in the writer's experience is far the best restor ative agent.
Artificial respiration should also be resorted to. This con sists of rhythmically contracting and expanding the chest by jerking pressure on the chest wall and by alternately extend ing and flexing fore limbs. Peri pheral irritation may also be good, such as a cold douche or flicking with a wet towel or a whip.
The cautious insufflation of strong ammonia is good as a cardiac and respiratory stimu lant. Amyl nitrite may be useful by dilating superficial vessels and so relieving the. heart. It may be either insufflated, or dropped on to the tongue, or injected sub cutaneously in doses of 10 to 20 minims for the horse and 1 to 2 minims for the dog. Hypo dermic injections of ether, liquor strychnina3, adrenalin, may all assist.
In favourable cases respiration starts with gasps in from one minute upwards, and hope should not be abandoned until the artificial respiration has been continued at least fifteen to twenty minutes, or so long as the heart beats, be it ever so feebly. If, however, the heart's action completely stops, the case is usually hopeless.
How does the Chloroform produce its Effects? —Very exhaustive experiments in this connec tion have been carried out by Dr. G. A. Buckmaster and his co-worker J. A. Gardner, and their results are published in the Proceed ings of the Royal Society. They have shown that the effects of chloroform depend upon the exchange of gases in the pulmonary alveoli and blood, and that the red corpuscles alone act as the chloroform carriers. In the early stages the absorption is very rapid, and less so later on. The red corpuscles convey it to the various parts of the body, and dis charge certain small amounts to the tissues, and especially to the central nervous system. The first effect of that is to stimulate the nerve centres, and this stimulation may even approach a lethal value constituting the first danger point previously referred to. It may cause cessation of respiration owing to paralysis of the respiratory nervous mechanism, and is more likely to occur as the result of a deep and rapid respiration and a higher percentage of the drug administered. If this stage is safely passed, the cerebral centres become depressed and complete anaesthesia may be attained safely. If the chloroform is continued in high dilution, elimination takes place by expired air and an equilibrium is established. If, however, a larger quantity of chloroform is rapidly adminis tered, it gets into the plasma, and is co-existent with a decidedly dangerous stage in which the respiratory centre is over-depressed and breath ing stops.
The facts that in respiratory chloroform anaesthesia the red corpuscles transport the drug and that chloroform is not present in the plasma except in dangerously advanced stages, would appear to explain the lack of success following the attempts to produce anaesthesia by the intravenous injection of chloroform. In the opinion of the writer such a method, though worthy of further investigation, does not appear very promising.
and When the operation is about completed the chloroform inhaler is removed, but in the horse the hobbles should be kept on until consciousness has fully returned. It is a mistake to allow a horse to attempt to rise until there is a reasonable prospect of his being able to support himself. The time required may be from five minutes to half an hour, or occasionally even longer. If a horse has been lying long on the one side, the writer has frequently noted that he is likely to rise more quickly and is more able to support himself if he is turned over on to his other side a few minutes before he is allowed to attempt to get up. If after a reasonable interval he does not make any effort to rise, he may often be induced to do so either by flicking with a wet towel or a whip, or by pouring a little water into an ear. When rising he should be supported by an attendant with a short hold of the bridle, and another attendant at the tail. He should then be kept slowly moving with his head to the wind until he com pletely gains his equilibrium. He may then be put into a loose-box, but should not be secured by the head in case he should fall again. About an hour later lie may be offered a drink of tepid water or oatmeal gruel, mashes being offered later. During the first day dry foods and long hay should be withheld.
In the case of the dog he should be placed quietly into his apartment and only offered a little milk or a little tepid water for the next few hours. Sometimes the patient will only feed capriciously the next day as the result of nausea, but this condition rarely lasts longer.
Unfavourable sequelce to chloroform in our patients are very rare. Occasionally a nostril may be blistered when a sponge has been applied to an imperfectly lubricated nose. Pneumonia is sometimes spoken of as being a sequel, but the writer, in an experience involving the use of chloroform in many thousands of cases, has never met with pneumonia directly attributable to chloroform.
Ether compared with Chloroform as a General Anaesthetic.
Ether is more disagreeable to the taste and causes a much larger increase in salivation than chloroform. The preliminary stage of excite ment is longer and the anaesthesia more tran sient. On the other hand, it is less dangerous, owing to its less depressant effects. Therefore it is safer to use on patients with weak hearts, and young or fat patients. It must, however, be administered in a much more concentrated form as half ether vapour and half air, condi tions which make it very difficult to use for large animals.
A.C.E. mixture and A.E.C. mixture occupy intermediate positions between ether and chloro form.
In the writer's experience, however, chloro form is by far the best agent for the production of general inhalation anaesthesia.
The Combination of a Narcotic and a Local Anaesthetic.
The application of respiratory has the disadvantage of requiring a trained thetist as well as the operator, and owners frequently refuse to pay adequately for such services. A common alternative is for the operator to administer the chloroform and direct it at the same time as operating; an objection able alternative for obvious reasons.
Consequently, for dogs the writer very fre quently dispenses with chloroform and employs a large dose of morphia, with or without the addition of a local anaesthetic according to the case. The dose, injected hypodermically, varies from a grain, in a puppy of the toy breeds, to 2 grains or even 3 grains for adults of the large varieties. After such injection the dog usually vomits in from one to five minutes, and some times and urine are evacuated. Narcosis is complete in about three-quarters of an hour, when the operation can be proceeded with. One great advantage of this method is that the dog remains in a state of stupor for eighteen to twenty-four hours, and so refrains from inter fering with the operation wounds. For major operations involving the peritoneal cavity a few whiffs of chloroform may be necessary, but great care must be taken, as the excitant stage is practically non-existent and complete anaes thesia is very rapidly produced with a minimum of chloroform.
Chloral hydrate, administered per os, or injected into the peritoneal cavity in dogs, has not given such satisfactory results in the writer's experience.
The use of morphia and of chloral hydrate in the horse have also been disappointing, and we have not persisted with them, mainly because we have always found the horse to be such an excellent subject for chloroform.