Chapter 15

GENERAL REMARKS ON OPERATIONS ON THE FOOT

A. METHODS OF RESTRAINT.

Many of the simple operations on the foot, such as the probing of a sinus, the paring out of corns, or the searching of pricks, may most suitably be performed with the animal's leg held by the operator as a smith holds it for shoeing. According to the temperament of the animal, even the operation for the removal of a portion of the sole, or the injection of sinuses with caustics, may be carried out with the animal simply twitched.

When the operation is still a simple one, casting inconvenient or impossible, and the animal restive, the twitch must be supplemented by some other method. The most simple and one of the most effective is the blind, cap, or bluff (Fig. 38). With it the most vicious animal or the most nervous is in many instances either cowed into submission or soothed into quietness.

At the same time, more forcible means than the operator's own strength must be taken to hold the animal's foot from the ground. If the foot is a fore-foot, and the point desired to be operated on is to the outside, the pastern should be firmly lashed to the forearm by means of a thin, short cord, or a leather strap and buckle. Much may then be done in the way of paring and probing that would otherwise be impossible.

If the foot is a hind one, one of the many methods of using what is termed by Liautard, in his 'Manual of Operative Veterinary Surgery,' the plate-longe, must be adopted. This, in its most useful form, is a length of closely-woven cotton webbing, from about 2 to 2-1/2 inches wide, and from 5 to 6 yards long, provided with a small loop formed on one of its ends, and perhaps better known to English readers as a 'side-line.' If webbing be not available, a length of soft cotton rope, or a rope plaited and sold for the purpose, as Fig. 39, will serve equally well. One of the most convenient methods of using the side-line for securing the hind-foot is depicted in Figs. 40 and 41.

Here the side-line has formed upon it a loop sufficiently large to form a collar. This is placed round the animal's neck, the free end of the line run round the pastern of the desired foot, and the foot drawn forward, as in Fig. 40.

The loose end of the line is then twisted once or twice round the tight portion, and finally given to an assistant to hold (see Fig. 41). The foot is thus held from the ground, and violent kicking movements prevented.

Where the operation is a major one, restraint of a distinctly more forcible nature becomes imperative. Many of the more serious operations can most advantageously be performed with the patient secured in some form or other of stock or trevis, and the foot suitably fixed. It is not the good fortune of every veterinary surgeon, however, to be the lucky possessor of one of these useful aids to successful operating. Perforce, he must fall back on casting with the hobbles (Fig. 42).

With the use of these we will assume our readers to be conversant, and will imagine the animal to be already cast. It remains, then, but to detail the most suitable means for firmly fixing the foot to be operated on.

Here the side-line is again brought into use. Care should previously have been taken when casting to throw the animal so that the portion of the foot to be operated on, whether inside or outside, falls uppermost, and that the buckle of the hobble on that particular foot is placed so that it also is within easy reach when the animal is down.

In the case we are illustrating the point of operation was the outside of the near hind coronet. We will, therefore, describe the mode of fixing the near hind-foot upon the cannon of the near fore-limb.

The side-line is first adjusted as follows: It is fixed upon the cannon of the near hind-leg (A) by means of its small loop. From there it is passed under the forearm of the same limb, over the forearm, under the rope running from A to B; from there over and under the thigh, to be finally brought in front of the thigh, and below the portion of rope running from arm to thigh. The loose end of the side-line is then given to an assistant standing behind the animal's back, the buckle of the hobble restraining the foot unloosed, and strong but steady traction brought to bear from behind upon the line. The operator should now stand in front of the fore-limbs, and, by placing a hand on the rope passing round the arm, prevent the line from slipping below the knee.

By this means the hind-limb is pulled forward until the foot projects beyond the cannon of the front-limb. When that position is reached, the operator grasps the hock firmly with one hand, and, directing the side-line to be slackened, gently slides downward the coils of rope round the arm and thigh until they encircle the cannons of both limbs. The cannon of the hind-limb is firmly lashed to the cannon of the fore, and the foot firmly and securely fixed in the best position for operating (see Fig. 44).

Similarly, with the horse still on his off side, the off hind-limb may be fixed to the near fore, and the near fore and the off fore to the near hind.

With the animal on his near side, we may fix the near hind and the off hind to the off fore, and the off fore and near fore to the near hind.

The points to be remembered in fixing the limbs thus are: (1) The side-line should always commence upon the cannon of the limb to be operated on; (2) it should next pass under and over (or over and under, it is immaterial which) first the arm and then the thigh, or the thigh and the arm, as the case may be; (3) in every case, whether rounding the thigh and the arm from above or below, the piece of rope completing the round should always finish below that portion preceding it, so that traction upon it from behind the animal's back should tend to keep all portions of it from slipping below the knee and the hock.

With the uppermost fore-limb secured to the hind-limb in the manner we have described, we have the underneath fore-limb suitably exposed for both the higher and lower operations of neurectomy. The position for this operation will be made better still if the lowermost limb (the one to be operated on) is removed from the hobbles and drawn forward by an assistant by means of a piece of rope fastened to the pastern.

Taking what we have described as a general guide, other modifications of thus securing the foot will suggest themselves to the operator to meet the special requirements of the case with which he is dealing.

Regarding the administration of chloroform, no description of the method is needed here, as it will be found fully detailed in most good works on general surgery. Where great immobility is needed, it is one of the most valuable means of restraint we have. Apart from that, its use in any serious operation is always to be advocated, if only on the score of humane consideration for the dumb animal helpless under our hands.

B. INSTRUMENTS REQUIRED.

In addition to those required for operations on the softer structures--such as scalpels, forceps, artery forceps, directors, scissors, etc.--the surgery of the foot demands instruments specially adapted for dealing with the horn.

A great deal will depend upon the operator as to whether these are few or many. The average man of resource will deem a smith's rasp and one or two strong drawing-knives amply sufficient, and on no account should they be omitted from the list of those ready to hand.

The ordinary smith's drawing-knife (Fig. 45) is well known to almost everyone, and is well suited for much of the rougher part of the work. The careful following up of pricks, however, and some of the more special operations demanding removal of portions of the lateral cartilages call for instruments of a more delicate character and peculiar construction. These are to be found in the so-called sage-knife, and the modern (French) pattern of drawing-knife.

The modern drawing-knife differs from the smith's instrument in being attached to a straight, instead of a curved, handle, and in usually being sharp on both edges instead of only on one. These are made in various sizes (Fig. 46, _a, b_), and the blades flat, curved on the flat, or curved at an angle with the edges of the haft.

The sage-knife, as its name indicates, is a knife with a lanceolate-shaped blade. These also may be obtained in varying forms and sizes (Fig. 46, _c, d, e_). Fig. 46, _c_, is a single-edged, right-handed sage-knife. Fig. 46, _d_, is a left-handed instrument of the same type. The double-edged sage-knife is represented in Fig. 46, _e_.

It may be mentioned too, in passing, that the ordinary Symes's abscess-knife (Fig. 47) is a most useful instrument when performing the operation of partial excision of the lateral cartilages, its peculiar shape lending itself admirably to the niceties of the operation.

One or two good-shaped firing-irons will also be found useful. They will lighten the labour of tediously excavating grooves with the knife, where that procedure is necessary; and, used in certain positions to be afterwards described, will afford just that necessary degree of stimulus to the horn-secreting structures of the foot, which the use of the knife alone will not.

The man in country practice will also be well advised in carrying to every foot case a compact outfit, such as that carried by the smith. This will consist of hammer and pincers, drawing-knife and buffer. Much valuable time is then often saved which would otherwise be wasted in driving round for the nearest smith.

There are other special operations requiring the use of specially-devised instruments for their successful carrying out. These we shall mention when we come to a consideration of the operations in which they are necessary.

C. THE APPLICATION OF DRESSINGS.

One of the most common methods of applying a dressing to the foot is poulticing. Usually resorted to on account of its warmth-retaining properties, the poultice may also be medicated. In fact, a poultice, strongly impregnated with perchloride of mercury or other powerful antiseptic, is a useful dressing in a case of a punctured foot, or a wise preliminary to an operation involving the wounding of the deeper structures. The poultice may consist of any material that serves to retain heat for the longest time. Meal of any kind that contains a fair percentage of oil is suitable. Crushed linseed, linseed and bran, or linseed-cake dust are among the best.

To prepare it, all that is necessary is to partly fill a bucket with the material and pour upon it boiling water. The hot mass is emptied into a suitable bag, at the bottom of which it is wise to first place a thin layer of straw, in order to prevent the bag wearing through, and then secured round the foot. This is generally done by means of a piece of stout cord, or by straps and buckles fastened round the pastern and above the fetlock.

An improved method of fastening has been devised by Lieutenant-Colonel Nunn:

'A thin rope or stout piece of cord about 5 feet long is doubled in two, and a knot tied at the double end so as to form a loop about 5 or 6 inches long, this length depending on the size of the foot (as at A, Fig. 48). The poultice or other dressing is applied to the foot, and the cloth wrapped round in the ordinary way, the loop of the cord being placed at the back of the pastern (as in A, Fig. 49); the ends of the cord are passed round, one on the inside and the other on the outside, towards the front (as in B, Fig. 49). These ends are then twined together down as far as the toe (see C in Fig. 49). The foot is now lifted up, and the ends of the cord (CC, Fig. 49), are passed through the loop A (as at D, Fig. 49), and then drawn tight. The ends of the cord are now separated, and carried up to the coronet (as at EE, Fig. 49), one on the outside, the other on the inside of the foot. They are then again twisted round each other once or twice (as at F, Fig. 50), and are passed round the pastern once or twice on each side. They are now passed under the cord (E, Fig. 49), and then reversed, so as to tighten up E, and are finally tied round the pastern in the usual manner. The arrangement of the cords on the sole is shown in Fig. 51, which is a view from the posterior part.

'The advantages of this method of fastening have been found to be: (1) It does not chafe the skin; (2) if properly applied it has never been known to come undone; (3) it is the only way we know that a poultice can be satisfactorily applied to a mule's hind-foot; (4) horses can be exercised when the poultice is on the foot, which is almost impossible with the ordinary leather boot; (5) the sacking or canvas does not cut through so quickly.'

A further method of applying the poultice is by using one of the poultice-boots made for that purpose (see Figs. 52 and 53).

These have an objection. They are apt to be allowed to get extremely dirty, and so, by carrying infective matter from the foot of one animal to that of another, undo the good that the warmth of the poultice is bringing about. The advantage of the ordinary sacking or canvas is that it may be cast aside after the application of each poultice. Where the boot is kept clean, however, it will save a great deal of time and trouble to the attendant.

While on the subject of poulticing, it is well to remark that in many cases it may be more advantageous to supply the necessary warmth and moisture to the foot by keeping it immersed in a narrow tub of water maintained at the required temperature. By this means the warmth is carried further up the limb (sometimes an important point), and the water can more conveniently be medicated with whatever is required than can the poultice. In fact, it is the author's general practice, where the attendants can be induced to take the necessary pains, to always advise this latter method.

Where a dressing is relied upon by some practitioners on account of the warmth it gives, others, even in identical cases, will depend upon the effects of cold. This may be applied by means of what are called 'swabs.' In their simplest form swabs may consist only of hay-bands or several layers of thick bandage bound round the foot and coronet, and kept cool by having water constantly poured upon them. In many cases the form of swab depicted in Fig. 54 will be found more convenient.

When only one foot is required to be dressed, and a water-supply is available, by far the preferable method is to attach one end of a length of rubber tubing to the water-tap, and fasten the other just above the coronet, allowing the water to trickle slowly over the foot. In cases where a forced water-supply is unobtainable, and the case warrants the extra trouble, much may be done with a medium-sized cask of water placed somewhere over the animal, and the rubber tubing connected with that.

Where the dressing is desired to be kept applied to the sole and frog only, there is no method more satisfactory than the shoe with plates.

The plates are of metal, preferably of thin sheet iron or zinc, and are slipped between the upper surface of the shoe and the foot after the manner shown in Fig. 55. The plates themselves are shaped as depicted in Fig. 55, _a, b, c, a_ and _b_ curved to meet the outlines of the shoe, and _c_ shaped so as to wedge tightly over the posterior ends of the side plates, and between them and the shoe. A distinct advantage of the plate method of dressing is that a certain amount of pressure may be maintained on the sole and frog, a very important consideration in connection with some of the diseases with which we shall later deal.

When dealing with sinuous wounds of the foot, another favourite mode of applying dressings is by means of the syringe, and no better instrument for all cases can be found than that known as a quittor syringe (Fig. 56).

A further mode of applying dressing, and one frequently practised in connection with the foot, is known as 'plugging.' This is almost sufficiently indicated by its name. It consists in rolling portions of the dressing into little cylinders, wrapped round with thin paper, and introduced into a sinus or other position where considered necessary.

D. PLANTAR NEURECTOMY.

As a last resort in the treatment of many diseases of the foot the operation of neurectomy is often advised. It will be wise, therefore, to insert a description of the operation here.

_Derivation of the Word_.--For many years the operation was known simply as 'nerving' or 'unnerving,' and it was not until 1823, at the suggestion of Dr. George Pearson, that Percival introduced the word _neurotomy_ to signify the operation with which we are now about to deal. The word neurotomy, however, used strictly, means the act or practice of dissection of nerves, and, when applied to the operation as practised to-day, describes only a step in the procedure.

As the operation really consists in cutting down upon, and afterwards excising a portion of the nerve, the modern appellation of _neurectomy_--from the Greek _neuron_, a nerve; and _tome_, a cutting, signifying the cutting out of a nerve or the portion of a nerve--is far more suitable.

According as the nerve operated on is the plantar or the median, the operation is known as plantar or median neurectomy.

_History of the Operation_.--It is to two English veterinarians that we owe the introduction of the operation to the veterinary world. In 1819 Professor Sewell announced himself as the originator of neurotomy. This claim was disputed by Moorcraft, who appears to have successfully shown himself to be the real person entitled to that honour, he having satisfactorily performed the operation on numerous animals for fully eighteen years prior to Professor Sewell's announcement. It appears that Moorcraft left this country for India in 1808, having practised the operation in more or less obscurity for some six or seven years previous to that. After his departure neurectomy, as introduced by him, either died away in repute, or was not made by him sufficiently public to become a matter of general knowledge. To Professor Sewell, therefore, although not the actual originator of the operation, belongs the honour of making it public to the veterinary profession.

In 1824, five years after Sewell's introduction, we find it practised on the Continent by Girard. We gather, however, from the writings of Percival and Liautard, that both in this country and on the Continent the operation was for several years largely in the stage of experiment. Unsuitable subjects were operated on; the work afterwards given to the animal improperly adjusted to his altered condition; and the bad after-results of the operation almost ignored by some, and greatly exaggerated by others. In fact, some long time elapsed before veterinary surgeons allotted to the operation that measure of credit which the results following it warranted.

_The Object of the Operation_ is to render the foot insensitive to pain, and to give to an otherwise incurably lame animal a further period of usefulness. After the operation, as time goes on, this object may become defeated by the reunion of the divided ends of the nerve. In that case, neurectomy must necessarily be performed again.

_The Operation_.--Two forms of neurectomy are recognised--the high operation and the low. The low operation deals with the posterior digital branch of the plantar nerve, and the high operation with the plantar itself.

It is the latter operation with which we shall deal first. In our opinion it is that most likely to be followed by satisfactory results. The area supplied by the posterior digital is mainly the posterior portion of the digit. Thus, unless the cause of the lameness is diagnosed with certainty to be situated somewhere in the posterior region of the foot, section of the posterior digital alone will not give total insensibility to pain. Added to that, we may remember this: Below the point at which the digitals branch off from the plantar there is always more likelihood of the part we are attempting to render insensible being supplied by another and adventitious branch, or a branch that, as regards its direction, is abnormally distributed. As a last consideration, we may say that the higher operation is the easier to perform.

Percival, in his works on lameness, has some very sage remarks to make by way of a preliminary, and we cannot do better than quote them here. He says:

'To command success in neurectomy three considerations demand attention:

'1. The subject must be fit and proper; in particular, the disease for which neurectomy is performed should be suitable in kind, seat, stage, etc.

'2. The operation must be skilfully and effectually performed.

'3. The use that is made of the patient afterwards should not exceed what his altered condition appears to have fitted him for.

'The veterinarian who is guided by considerations such as those will find that he has restored to work horses who would otherwise have been utterly useless. A plain and safe argument wherewith to meet the objections to neurectomy is simply to ask the question what the animal is worth, or to what useful purpose he can be put, that happens to be the subject of such an operation.

'If the horse can be shown to be still serviceable and valuable, then he is not a legitimate subject for the operation. The rule of procedure I have laid down is to operate on no other but the _incurably lame horse_; and whenever this has been attended to, not only has success been the more brilliant, but indemnification from blame or reproach has been assured.'

_Preparation of the Subject_.--But little in the way of medicinal preparation is necessary. When the animal is a gross, heavy feeder, and carries a more than ordinary amount of cupboard, all that is needed is to withhold his usual allowance of food for some time prior to the operation, simply to avoid risk of rupture when casting. If considered advisable, a dose of physic may also be administered.

To the seat of operation, however, careful attention should be given. On the day previous to the operation the hair should be closely removed with the clipping machines, and the skin thoroughly cleansed with warm water and soap. After this, a bandage soaked in a 4 per cent, watery solution of carbolic acid should be wrapped lightly round the limb, and allowed to remain in position until the animal is cast and ready for the operation the following morning. On removing the bandage prior to operating, the part should again be bathed with a cold 5 per cent. solution of carbolic acid and swabbed dry. Attention to these details will serve to leave the wound in that favourable condition in which it heals nicely, and with the minimum amount of trouble.

_Preliminary Steps_.--By some practitioners the operation is performed with the animal standing, local anæsthesia having been first obtained by the use of cocaine, or an ethyl chloride spray. There is no gainsaying the fact, however, that the operation of neurectomy is a painful one, and that, with most operators, success will be more fully guaranteed with the animal cast and the limb held in a suitable position by an assistant.

The animal is thrown by the hobbles upon the side of the leg which is to be operated on. The cannon of the upper fore-limb is then fixed to the cannon of the upper hind, as described under the section of this chapter devoted to the methods of restraint, and the lower limb freed from the hobbles and drawn forward by an assistant by means of a stout piece of cord round the pastern.

An alternative method of holding the limb is to bind both fore-legs together above the knee by means of the side-line run round a few times in the form of the figure 8, and then fastened off. As in the former method, the lower foot is then removed from the hobble, and again held forward by an assistant. By either method the inside of the limb is operated on first.

Although it is not absolutely necessary, it is an advantage, especially to the inexperienced operator, to apply before operating an Esmarch's bandage and tourniquet (Fig. 57). This expels the greater part of the blood from the limb, and renders the operation comparatively bloodless.

The Esmarch bandage is composed of solid rubber, and with it the limb is bandaged tightly from below upwards. On reaching the knee the tourniquet is stretched round the limb, fastened by means of its buckle and strap, and the bandage removed. Those who feel they can dispense with the bandage use the tourniquet alone. For this purpose the form depicted in Fig. 58, and the one in general use at the Royal Veterinary College, is more suitable, on account of its wooden block, which may be placed so as to press on the main artery of supply.

_Instruments Required_.--These should be at hand in an earthenware or enamelled iron tray containing just sufficient of a 5 per cent. solution of carbolic acid to keep them covered. Those that are necessary will be a sharp scalpel, or, if preferred, one of the many forms of bistoury devised for the purpose (see Fig. 59), a pair of artery forceps, a needle ready threaded with silk or gut, one of the patterns of neurectomy needle (see Fig. 60), and a pair of blunt-pointed scissors curved on the flat. It is also an advantage, when once the incision through the skin is made, to employ one of the forms of elastic, self-adjusting tenacula (see Fig. 61) for keeping the edges of the wound apart while searching for the nerve.

_Incision through the Skin_.--We remember that the plantar nerve of the inner side is in close relation with the internal metacarpal artery, and that both, in company with the internal metacarpal vein, run down the limb in close proximity with the inner border of the flexor tendons. Also, we remember that the external plantar nerve has no attendant artery, although, like its fellow, it is to be found in close touch with the edge of the flexor tendons.

Bearing these landmarks in mind, we feel for the nerve in the hollow just above the fetlock-joint by noting the pulsations of the artery, and determining the edge of the flexor tendons. This done, a clean incision is made with the bistoury or the scalpel in the direction of the vessels. The incision should be made firmly and decisively, so that the skin may be cleanly penetrated with one clear cut. If judiciously made, little else in the shape of dissection will be needed.

It is now that the double tenaculum (Fig. 61) is applied. One clip is fixed to the anterior edge of the wound, and the other carried beneath the limb and made to grasp the posterior edge. If found desirable to keep the edges of the wound apart, and no tenaculum to hand, the same end may be accomplished by means of a needle and silk. In like manner as is the tenaculum, the silk is attached to one edge of the wound, carried under the limb, and firmly secured to the other.

Having made the incision, the wound should be wiped free from blood by means of a pledget of cotton-wool previously soaked in a carbolic acid solution and squeezed dry. At the bottom of the wound will now be seen the glistening white sheath, containing the vein, artery, and nerve. This should be picked up with the forceps, and a further incision made with the bistoury. Care should be exercised in making this second incision, or the artery may accidentally be opened. If an ordinary scalpel is used, the lower end of the sheath should be picked up and the point of the scalpel inserted through it. With the cutting edge of the scalpel turned towards the opening of the wound, the sheath is then slit from below upwards. The second incision satisfactorily made, the wound is again wiped dry, and the nerve seen as a piece of white, curled string in the posterior portion of the wound.

At this stage it is advisable to accurately ascertain whether what we have taken to be the nerve actually is it. This is done by taking it up with the forceps and giving it a sharp tweeze. A sudden struggle on the part of the patient will then leave no doubt in the operator's mind that it is the nerve he has interfered with.

_Section of the Nerve_.--The neurectomy needle (Fig. 60) is now taken, and, excluding the other structures, passed under the nerve. A piece of stout silk or ordinary string is then threaded through the eye of the needle, the needle withdrawn, and the silk left in position under the nerve. The silk is now tied in a loop, and the nerve by this means gently lifted from its bed. With the curved scissors or the scalpel it is severed as high up as is possible. The lower end of the severed nerve is then grasped firmly with the forceps, pulled downwards as far as possible, and then cut off. At least an inch of the nerve should be excised.

The animal is then turned over, and the opposite side of the limb operated on in the same manner.

The tourniquet is now removed, and the wound is examined for bleeding vessels. If the hæmorrhage is only slight, the wound should be merely dabbed gently with the antiseptic wool until it has stayed. A larger vessel may be taken up with the artery forceps and ligatured, or the hæmorrhage stopped by torsion. On no account, unless it it done to stay hæmorrhage that is otherwise uncontrollable, should the wound be sutured with blood in it. With the wound once dry and clean, it is well to insert three or four silk sutures, but care must be taken not to draw them too tightly. This done, the patient may be allowed to get up. _After-treatment_.--This is simple. Over each wound is placed a pledget of antiseptic cotton-wool or tow, and the whole lightly covered with a bandage soaked in an antiseptic solution. For the first night the animal should be tied up short to the rack, and the following morning the bandages removed. A little boracic acid or iodoform, or a mixture of the two combined with starch (starch and boracic acid equal parts, iodoform 1 drachm to each ounce) should now be dusted over the wounds, the antiseptic pledgets renewed, and the bandage readjusted over all.

At the end of three or four days the bandages may be dispensed with. All that is necessary now is an occasional dusting with an antiseptic powder, and, as far as possible, the restriction of movement. At the end of a week the sutures may be removed, and the animal turned into a loose box or out to pasture.

E. MEDIAN NEURECTOMY.

As a palliative for lameness when confined to the foot, one would imagine that the plantar operation would be all sufficient. There are operators, however, who state that the results following section of the median nerve have been such as to cause them to entirely abandon the lower operation in its favour. If only for that reason a brief mention of the operation must be made here.

The operation was first performed in this country in October, 1895, the subject being one of the out-patients at the Royal Veterinary College Free Clinique.

For five or six years following this date Professor Hobday performed the operation some several hundred times, and was certainly instrumental in bringing the operation into prominence. Though so recently introduced here, it appears to have been practised for several years on the Continent, originating in Germany as early as 1867. In that country a first public account of it was published in 1885 by Professor Peters of Berlin, while in France it was introduced by Pellerin in 1892. In this operation a portion of the median nerve is excised on the inside of the elbow-joint just below the internal condyle of the humerus. Here the nerve runs behind the artery, then crosses it, and descends in a slightly forward direction behind the ridge formed by the radius.

The position of the limb most suitable for the operation is exactly that we have described as most convenient for the plantar excision. The animal is cast, preferably anæsthetized, and the limb removed from the hobbles, and held as far forward as is possible by an assistant with the side-line.

Professor Hobday's description of the operation is as follows:

'A bold incision is made through the skin and aponcurotic portion of the pectoralis transversus and panniculus muscles, about 1 to 3 inches (depending on the size of the horse) below the internal condyle of the humerus, and immediately behind the ridge formed by the radius. This latter, and the nerve which can be felt passing over the elbow-joint, form the chief landmarks. The hæmorrhage which ensues is principally venous, and is easily controlled by the artery forceps. In some cases I have found it of advantage to put on a tourniquet below the seat of operation, but this is not always advisable, as it distends the radial artery. We now have exposed to view the glistening white fascia of the arm, which must be incised cautiously for about an inch. This will reveal the median nerve itself situated upon the red fibres of the flexor metacarpi internus muscle. If not fortunate enough to have cut immediately over the nerve, it can be readily felt with the finger between the belly of the flexor muscle and the radius.'[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. ix., p. 181.]

The nerve exposed, the remainder of the operation is exactly as that described in removing the portion of the nerve in the plantar operation. The wound is sutured and suitably dressed, and a fair amount of exercise afterwards allowed the patient.

F. LENGTH OF REST AFTER NEURECTOMY.

This is placed by the majority of surgeons at about three weeks to a month. Within that period no excessive exertion should be undergone by the patient. A certain amount of quiet exercise, however, is beneficial, facilitating the healing of the wounds, and accustoming the animal to the altered condition of his limb.

G. SEQUELÆ OF NEURECTOMY.

These we shall relate collectively, making no distinction between those following excision of the plantar nerve and those succeeding section of the median. It must be remembered by the surgeon, however, that the unfortunate sequelæ we are now about to describe are likely to be far more grave when following section of the larger nerve.

_Liability of Pricked Foot going undetected_.--On account of the warning they convey to the surgeon, first place among the sequelæ of neurectomy must be given to accidents following loss of sensation. Take, for example, punctured foot. In any case, in the sense of being unforeseen, it is accidental. In the neurectomized foot it becomes doubly accidental, in that not only is it unforeseen, but that it is for some time indiscoverable. With the foot deprived of sensation, a nail may be picked up, or a prick sustained at the forge, and no intimation given to the attendant until pus has underrun the horn, and broken out at the coronet. What follows, then, is that the hoof as a whole, or the greater part of it, sloughs off.

No neurectomy should be undertaken unless this contingency has been allowed for. The owner should be advised of it by the surgeon, who should at the same time enjoin on his client the absolute necessity of giving to the neurectomized foot daily and careful attention.

_Loss of Tone in the Non-sensitive Area_.--In addition to the mischief resulting from a wound going undetected, it must be remembered that the loss of tone resulting from the operation gives to every wound (however slight), in the region supplied by the removed nerve, a sluggish and troublesome character. Difficult to deal with as wounds about the foot ordinarily are, they are rendered more so by a previous neurectomy.

_Gelatinous Degeneration_. This is a condition liable to occur in cases where the operation has been too long deferred, and when considerable structural alteration has already taken place in the shape of diseased bone or tendon, more especially in navicular disease. It consists in a peculiar softening of the structures of the limb, accompanied with enlargement, due to swelling of the connective tissues, the enlargement and softening generally making itself first apparent by a soft, pulpy swelling in the hollow of the heel.

From this onwards the enlargement increases, and lameness becomes excessive, the animal going more and more on his heels, until, finally, no portion of the solar surface of the foot comes to the ground at all.

The case is hopeless, and destruction should be advised.

_Reported Case_.--'The patient, a brown carriage gelding, was brought to the Royal Veterinary College infirmary in a cart on December 31, the only previous history obtainable being that it had suddenly fallen lame a month before.

'The symptoms presented were excessive lameness of the near fore-limb. On being trotted, the toe was elevated each time the foot reached the ground, progression being entirely on the heels. Separation of the hoof for about 2 inches at the hinder part of the coronet; oedematous swelling from foot to knee, extending during the next three days to the elbow. Great tenderness between the knee and the fetlock; below this no sensation whatever, as a pin was inserted in several places round the coronet without causing any symptoms of pain. On further examination, two unnerving scars were found. No treatment was adopted, and the horse was destroyed on January 6.

'On dissecting the leg, the following appearances presented themselves:

'The limb was very much enlarged, due to thickening of the connective tissue, the skin being removed only with difficulty. The tendons were soft and much thickened. A rupture of the skin at the coronet, just where the skin meets the wall of the foot. Large extravasations of blood at the back of the tendons, situated in the lower half. _External_ nerve trunk had become reunited, at the point of junction there being a hard lump about the size of a walnut. _Internal_ nerve trunk also had become reunited, and presented a thickened portion at the point of junction, but not so large as that of the outer side, and situated in the lower half of the tendon, about 2 inches higher than that on the external nerve. This nerve trunk was atrophied below the thickening, and had undergone gelatinous degeneration. Judging from the scars on the skin, this side had evidently been unnerved a week or ten days previously to that on the outer side. The band stretching across the back of the perforatus, between the external and internal nerves, appeared on the inside to have become firmly fixed into the tendon.

'On removing the hoof, under the sole there appeared a large quantity of very foetid pus; the laminæ were very much inflamed in patches. There was an enormous thickening of connective tissues in the heel. On cutting longitudinally through the perforatus tendon, there was exposed a large blood-coloured mass, of a gelatinous appearance, situated on the perforatus tendon, the latter being very much thickened, and growing to the navicular bone. The underneath surface of the superior suspensory ligament was much thickened, and firmly adherent to the bone; at the posterior surface of the metacarpus there was a quantity of gelatinous substance. The anterior ligament of the fetlock-joint was thickened; the navicular bone was entire, but showed lesions of navicular disease, being ulcerated. Section through the bone did not reveal anything further. It may be here remarked that the ulcerations were on either side of the central ridge, and not at all on the ridge itself.

'Microscopic examination of the tissue joining the two ends of the nerve together revealed a few nerve fibres; the general appearance was that of granulation tissue, containing capillary vessels, which were fairly plentiful, and comparatively large in size.'[A]

[Footnote A: _Veterinary Record_, vol. iv., p. 386 (Hobday)]

_Chronic Oedema of the Leg_.--In some cases there is a distinct swelling of the leg some time after the operation. This exposes the limb to the infliction of sores from striking with the opposite foot, with, of course, the difficulty in healing we have just described.

_Persistent Pruritus_.--This annoying sequel occurs in the neurectomized limb, with or without gelatinous degeneration, and appears to be without a remedy. The itching in some cases is so intense as to lead the animal to constantly gnaw at the top of the foot. As one observer has remarked, the animal may begin literally biting pieces out of his limb. The result of the irritation and gnawing is fatal. Great sloughing of the parts takes place, and the animal has eventually to be slaughtered.

_Fracture of the Bones_.--The sudden loss of sensation in a foot may cause the animal to use violently the limb he has for months past been carefully nursing. It may be that the lameness for which the operation has been performed has been due to disease existing in the navicular bone, and extending, perhaps, to the os pedis. By the disease the bone has already been made brittle, its substance and ligamentous attachments perchance weakened and broken up by a slow-spreading caries, and rarefaction of the remaining bone substance rendered almost certain. In this instance, the free use of the foot, and the application to the diseased structures of an unwonted pressure immediately after the operation results in fracture. With the rupture of the structures we get the elevated toe and soft swelling in the heel, as described in gelatinous degeneration. Treatment, of course, is out of the question.

_Neuroma_.--A further sequel is the appearance at the seat of the operation of what is termed an 'amputational neuroma.' This is a tumour-like growth occurring on the end of the divided nerve. It is composed of connective-tissue elements permeated by nerve fibres which have grown out from the axis-cylinders of the nerve stump. It may vary in size from a pea to a hazel-nut, and is frequently the cause of much pain. This must be cut down upon and cleanly removed, taking away at the same time as much of the nerve as is possible.

_Reunion of the Divided Nerve_.--We may say at once that 'reunion' in the popular sense of the word does not take place. At a varying period after section, however, we do get a return of sensation. This is brought about in the following manner: The axis-cylinder of the nerve, still in connection with the spinal cord, swells somewhat, and hypertrophies. The cells of this hypertrophied portion show a great tendency to proliferate and produce new nerve structure. This growing point splits, and gives rise to several fibrils, which are new axis-cylinders. These commence to grow towards the periphery, and, in so doing, grow through the cicatricial tissue that has formed at the seat of the operation.

After passing through the cicatricial tissue (the amount of which tissue, of course, controls the length of time that insensibility remains), the growing axis-cylinders reach the degenerated portions of the nerve below the point of section. It is along the track of the old nerve that the new growths from the stump reproduce themselves.

The fact of the new growths having to pass through the fibrous tissue of the cicatrix before they can gain the course of the old nerve, along which latter their progress of growth is comparatively easy, affords ample illustration that as large a portion as is possible of the nerve should be removed when operating, in order to convey insensibility for the longest time. After reunion, of course, nothing remains but to repeat the operation.

_The Existence of an Adventitious Nerve-supply_.--While not exactly a sequel of the operation, the fact that it is not discovered until after the operation has been performed warrants us in mentioning it here. It is not an uncommon thing in the lower operation to find that sensation and symptoms of lameness still persist after section of the nerve. In many cases this has been traced to the existence of an abnormal nerve branch. In the higher operation this is not so likely to be met with. That it may occur, however, is shown by the following interesting case related by Harold Sessions, F.R.C.V.S.:[A]

[Footnote A: _Journal of Comparative Pathology and Therapeutics_, vol. xii., p. 343.]

'In June of 1898 I saw a hunter suffering from navicular disease. After carefully examining the leg, I advised the owner to have the operation of neurectomy performed upon him. This he decided to do, and the horse was sent to me about the beginning of July.

'The operation was performed in the ordinary way, without any difficulty whatever. The wounds healed nicely, but the horse still continued to go lame. Careful examination showed that there was still sensation on the outside of the foot. Thinking that possibly there might be two external metacarpal nerves, the horse was again cast, the operation being performed slightly lower down. Only the main branch of the external metacarpal nerve could be found. A piece of this was taken out, and the horse let up. On examination, sensation was still found in the posterior part of the outside of the foot. It was very evident that there was some abnormal distribution of the nerve, as sensation was still being conveyed to that part of the foot.

'As the horse was absolutely useless, and would have to be shot unless this piece of nerve could be found, he was again thrown, and after he had been anæsthetized I determined to follow the course of the nerve down, until I found where the accessory branch came from. This I found a little below the fetlock, about 1/2 inch below the point where the anterior plantar nerve is given off from the metacarpal nerve. It was about 1/2 inch below the spot where the anterior plantar nerve passes between the artery and vein of the foot, and it was somewhat difficult to get at it.

'Fig. 62 shows the exact size and distribution of the nerves. After the separation of the accessory branch, sensation was taken from the foot, and the horse went perfectly sound.'

_Stumbling_.--In addition to the sequelæ we have mentioned, it is urged against the operation of neurectomy that one of the first effects of depriving the foot of the sense of touch is a tendency on the part of the animal to stumble. From the cases we have seen we cannot regard this objection as a serious one. Nevertheless, as veterinarians, with a knowledge of the physiology of the structures with which we are dealing, we must treat the objection with respect, for, after all, we are bound to allow that stumbling, and a bad form of it, would be but a natural sequence of the operation we have just performed. The real fact remains, however, that cases of stumbling, even immediately after the operation, are rare; and that even when they do occur, the animal seems easily able to accommodate himself to the altered condition, and as readily uses the comparatively inert mass at the end of his limb as he did previously the intact foot.

H. ADVANTAGES OF THE OPERATION.

From the prominence we have given to the unfortunate sequelæ of the operation it might possibly be inferred that, while not giving it our absolute condemnation, we regard neurectomy with a certain amount of distrust. That we may contradict any such false impression, we state here that in many cases the operation is the only measure which will offer relief from pain, and restore to work an otherwise useless animal. In support of that we will now quote the recognised advantages of the operation.

That in many cases, when all other methods--surgical and medicinal--have failed, there is an immediate and total freedom from pain and lameness no one will deny. This, if it restores to active work an animal that would otherwise have had to have been cast aside, is ample justification for giving the operation, in spite of its many unfortunate terminations, a real place among the more highly favoured remedial measures to our hand.

'For _Contracted Hoofs_, viewing them in the light of idiopathic disease, or as being the immediate cause of the existing lameness in the uninflamed condition of the foot, and when consequential changes of its organism have taken place which bid defiance to therapeutic measures, _neurotomy_ is a _warrantable resource_' (Percival).

'For _Ringbone_ neurotomy has been practised with perfect success, after blistering and firing had both failed, notwithstanding the work the animal had to perform afterwards was of the most trying nature' (_ibid_.).

For _Navicular Disease_, when that malady is diagnosed, the earlier neurectomy is performed the better. The greater work given to the diseased bursa and bone, and the return of the contracted heels to the normal, brought about by the greater freedom with which the foot is used, are claimed by many to effect a cure.

Writing of navicular disease, and mentioning his belief in the possibility of the diseased bone effecting its own repair after the operation, Harold Leeney, M.R.C.V.S., says:

'The expansion of the heel, and rapid development of the frog (in this and many other cases) immediately after the operation, has not, I venture to think, attracted so much attention as it deserves, and may have something to do with those cases which appear to be actually _cured_, not merely made to go sound by absence of pain.'[A]

[Footnote A: _Veterinary Record_, vol. xi., p. 297.]

Speaking of the median operation before a meeting of the Central Veterinary Medical Society, Professor Hobday says:[A]

[Footnote A: _Veterinary Record_, vol. xiii., p. 427.]

'For old-standing lamenesses, when due to splints, exostoses, chronically sprained, thickened, and painful perforans and perforatus tendons, or cases of that kind which cause pain by pressing on the adjacent nerve structures, after all other known methods have failed, median neurectomy is the operation which will be most likely to give the animal a new lease of life and usefulness.'

'Of the _Humanity and Utility of Neurectomy_ there can be no question whatever, and provided the cases are well selected, and the operation is efficiently performed, the advantages to be derived from it are most striking as well as enduring. But the disadvantages attending the loss of sensation in the foot have been brought forward on many occasions as an argument against neurectomy, and no one can deny that the foot with sensation is better than one without that faculty. But in a long experience of the operation I have never found these disadvantages outweigh the great advantages which have immediately followed it.'[A]

[Footnote A: _Veterinary Journal_, vol. ix., p. 178 (Fleming).]

Beyond these, the direct advantages of neurectomy, are other and more indirect advantages which claim attention.

The most astonishing among them is the fact noted by many writers of repute that exostoses (ringbones, side-bones, splints, etc.) rapidly diminish in size. This is vouched for by such well-known authorities as Zundel and Nocard.

Percival, too, mentions at some length the effect of the removal of pain on the oestral and generative functions, quoting a case of a brood cart-mare by reason of bony deposits being stayed from breeding for some years. Two months after the operation she went to work, and moved sound, her altered condition leading her to breed several healthy foals.

I. THE USE OF THE HORSE THAT HAS UNDERGONE NEURECTOMY.

No operation is of any considerable value to the veterinary surgeon unless he is able to show that after it he has left his patient workable. The alleviation of pain alone, commendable as it is from a humanitarian standpoint, is of no interest to the average owner of horse-flesh, unless with it he sees his animal capable of justifying his existence by the amount of labour performed.

Criticised in this way, is the operation of neurectomy justifiable? Upon that point the opinions of many practitioners, even at the present day, differ. We have already partly answered the objections likely to be raised on this score by stating that the work afterwards allotted the animal should be fixed to suit his altered condition. It may be taken as a general rule that in all cases where the animal's usefulness depends upon his delicacy of touch, as, for example, animals used solely for hacking or hunting, his future usefulness in that special sphere of work will be done away with.

Percival himself, always a strong advocate for the operation, fully recognises this. 'Does the neurotomized horse maintain the same step as before?' he asks. 'To this important question,' he replies, 'I unhesitatingly answer no; he does not. There can be no doubt but that the horse _feels_ the ground upon which he is treading, and that he regulates his action in consonance with such feeling, so as to render his step the least jarring and fatiguing to himself, and therefore the easiest and pleasantest to his rider.... Such impressions'--those of touch--'being in the neurotomized subject, so far as regards the feeling of the foot, altogether wanting, a bold, fearless projection of the limb in action will be the consequence, followed by a putting down of the hoof flat upon the ground, as though it were a block, creating a sensation alike unpleasant both to horse and rider.'

Emphatic as Percival is upon this point, there are, nevertheless, others who maintain with equal stoutness that the unnerved animal is positively as safe, if not safer, than the animal who has not been so treated.

'That the tactile sense in the horse's foot is useful, it would be idle to deny; but that it is absolutely essential, even to safe progression, no one who has paid attention to the results of plantar neurectomy will maintain. On several occasions for years I have hunted, hacked, and driven horses which have been deprived of sensation in their fore-feet, and never had an accident with them. Their action has not been impaired by the operation; on the contrary, it has been vastly improved compared with what it had been previous to it. And my opinion has not been single in this respect, as many competent horsemen can give like evidence after long and severe trials of neurotomized horses. The opponents of neurotomy were, probably, not aware that there is in progression a _muscular_ as well as a _tactile sense_.'

This latter contention is supported by numerous cases, reported at the time when the operation of neurectomy was at the heyday of its popularity. Two I select from writings of a later period:

_Recorded Cases_.--1. 'Two of the finest among the many fine horses in the Second Life Guards were so lame from navicular disease, when I joined the regiment, that they were unsafe and unsightly to ride, and were therefore entered on the list to be cast off and sold. One was so crippled that it could scarcely be moved out of its stable. Peeling sorry at having to get rid of such good horses, and anxious to give another blow to the mistaken theory that unnerved animals were unsafe, I obtained the consent of my commanding officer, who patronizes practical conclusions, to perform neurotomy. This was carried out on both horses about eighteen months ago. Within a fortnight they were at their duty, absolutely free from lameness, and with first-rate action, and one of them, from being troublesome and unsteady in the ranks--probably from the pain in its feet--had become quite steady and tractable. Instead of being lame, blundering, and unsafe, both were sound, free in movement, and secure, and, the pain being abolished, they looked improved in condition.

'During the month of July the regiment attended the summer drills at Aldershot, and five days every week for a month these horses carried a weight of about 22 stones each over the roughest and most dangerous ground, nearly always at a fast pace, and for four, five, or six hours each day; and yet they never fell or blundered, and the troopers who rode them had unbounded confidence in their sure-footedness. They returned to Windsor, at the end of the month's severe test, as sound in their paces as when they left, and certainly now offer no indication whatever that they are less safe to ride than any other horse in the regiment. The effects of the relief from pain are also most marked, not only in the altered gait out of doors, but also in the stable.'[A]

[Footnote A: _Veterinary Journal, vol_. ix., p. 178 (George Fleming, F.B.C.V.S.).]

2. 'Some years ago I operated upon a valuable hunter, the property of a gentleman in Kildare, the animal having shown unmistakable symptoms of navicular disease for some months previously, and which had been unsuccessfully combated by the milder forms of treatment for the disease without any benefit. Although the horse went sound, the owner feared to ride him, and sent him to be sold in Dublin, where he was disposed of for a small price, and I then lost sight of him. The following Punchestown Races, to my surprise, amongst a group of horses walking round the paddock previous to saddling for an important race, I recognised my old patient, bandaged, clothed, and trained, ready to take his part in the cross-country contest, and surrounded by a host of admirers willing to back him at any price.

'Having satisfied myself that it was no other than the same animal, my first impulse was at once to find out the jockey who was to ride him, and warn him of his danger by telling him his mount was devoid of feeling in both fore-feet; but the saddling-bell had already rung, and in a few moments more the jockey emerged from the weighing-room and the next view of the horse was his tearing up the course in the preliminary, and "pulling double." I was sorry for the jockey if he felt as I did at that moment, for if he did I fear he and his horse would have parted company at the first fence, as I was certain there would be a smash before the end of the long and difficult three miles of the Kildare Hunt Cup course. It was not until I saw him again in the front rank passing the stand, in the first round, that I breathed freely, and even then I felt very guilty, and, had he come to grief badly, I don't think I should ever have operated on another horse except in such a way as would have left unmistakable traces after it.

'"The old horse wins!" screamed a thousand voices as the competitors safely cleared the last bank (now taken away for a gorse fence) the last time round, and from that moment the operation went up in my estimation a hundredfold, and I almost lost all interest in the finish (and it was a close one, with my patient a good third), resolving I would operate for the future on every animal, young and old, which showed symptoms of navicular disease.

'Neither owner nor jockey knew the horse had been operated on, and he was soon after, on the strength of his performance, sold for a good price to come to England. It is idle to think that all cases are as successful as this was, as experience soon told me; but I consider that, in careful hands, the advantages well outweigh the disadvantages of the operation, and I have selected this instance merely as a practical example.'[A]

[Footnote A: _Veterinary Journal_, vol. iii., p. 254 (W. Pallin, M.B.C.V.S.).]

It is solely with the object of ventilating both sides of the question that we quote the last two cases. In our opinion, the colours in which the results of the operation are there painted are far too rosy. The practitioner who has before him the task of satisfying a client as to what will or what will not be the results of an operation he has suggested will do well to weigh each side of the argument carefully, and endeavour in his explanation to strike the happy mean.

We hold, further, that the animal who has previously been accustomed to fast work, and to work entailing a large call upon the sense of touch when passing over rough and uneven ground, will be far more likely, in his neurectomized condition, to give satisfaction to his owner if put to a slower and a more suitable means of earning his living.