The large size of the pelvis, its projecting angles and position, render it specially liable to fracture, and modern road-making in our large towns contributes not a little to this result. Wood pavement, when the surface is first moistened with water, is rendered difficult to travel over at any time, but with heavy loads behind them, where the ground is on the ascent, or slopes, as it usually does, from the centre towards the sides, heavy horses frequently fail to keep their legs, and suffer fracture of this bone by a heavy and helpless fall. When the fall is on the side, and the force is applied to the point of the haunch, a portion of the angle of the ilium may be broken away from its body, or the fracture may take place in some remote and deeply seated part. Draught-horses, when moving heavy loads in two-wheeled carts, are sometimes brought to the ground by their hind-limbs suddenly slipping away from them right and left, when the pelvis is forced to the breaking-point by the weight of the load on the one hand and the struggles of the animal on the other.

Fig. 345. - Fracture or the Pelvis.

A, Fracture through the Cotyloid Cavity. B, Fracture of the Symphysis Pubis. c. Transverse Fracture of the Os Pubis. D, External Fracture of the Ischium. E, Fracture of the External Iliac Angle. F, Fracture of the Internal Iliac Angle. G, Fracture of the Tuberosity of the Ischium.

Blows on the hip while passing at high speed through doorways and gates, or by collision with some other fast-moving body, are also accountable for accidents of this kind, and in rare instances fracture has been brought about by "casting", or in the course of a surgical operation. In the hunting-field and the chase, horses have fractured their hips while jumping, as well as by dropping the hind-quarters into a drain as the result of failure to clear a bank.

From these and other causes fracture of the pelvis may take place in one or another of its various parts. Breakage of the point of the haunch (hip down) is the most frequent form which the accident assumes. Less frequently the body or the neck of the ilium may break, or the pubis or ischium which form the floor of the pelvis, or the bony cup (acetabulum) which is engaged in forming the hip-joint, or the breach may take place through the tuberosity of the ischium where it forms the point of the buttock. Of course more than one of these several parts may be rent at the same time.

Symptoms

Many and various phenomena result from fracture of the pelvis, and veterinarians have attempted to assign to each particular fracture its special set of symptoms, but it cannot be said that they have yet established a reliable code. The physiological disturbance which results from the fracture of any particular part of the pelvic girdle is sometimes so masked and disturbed by injuries occasioned to neighbouring muscles that the symptoms of no two cases of the same fracture sufficiently resemble each other to ensure correct diagnosis unless the fracture can be localized by the hand through the rectum.

Sudden lameness, more or less severe, according to the seat and nature of the breakage and the extent of displacement, is the immediate effect of the mishap; or the animal may be so far disabled at once as to be unable to rise when down or to stand when up.

In some cases there is obvious deformity of the quarter. In fracture of the neck or the inner angle of the ilium the croup becomes depressed, and when compared with the sound side, while weight is on the leg, it is noticed to be distinctly lower. Fracture of the outer angle of the ilium gives the quarter a flat appearance on the side of the injury, owing to the broken piece having been pulled downwards by the muscles attached to it. This is soon recognized by inspecting the quarters first from before and then from behind.

When the outer branch of the ischium is fractured, there may be more or less swelling in the region of the hip-joint and about the inner and back part of the thigh.

In fracture of the pubis, swelling of a diffused character appears sooner or later between the thighs, about the sheath and scrotum in the horse and the mammary gland in the mare. It may also extend in a forward direction beneath the belly, or in a backward direction to the perineum in the male or the vagina in the female.

Excepting in fracture of the outer angle of the bone (hip down) locomotion is very materially interfered with, and the power to bear weight is either seriously impaired or altogether destroyed.

In progression the limb on the side of the fracture may be moved unduly outward (abducted) or inward (adducted), or the animal experiences difficulty in bringing it forward or in raising it from the ground. The horse fails to walk straight but moves diagonally with the rump inclined towards the sound side. In some fractures, especially those involving the acetabulum or hip-joint, pain is expressed by a more or less audible grunt, by spasmodic twitching of the muscles, and an expression of anxiety and fear. Where the round ligament (fig. 358) is in part or wholly detached from its connection with the cup, the limb ceases to be altogether under muscular control. In any attempt to move it, either the foot goes beyond or falls short of the point it is intended to reach. In one step it is thrown outwards, while in the next it may incline inwards, and the movement of the limb generally is limp.

The diagnostic symptom in this, as in all other fractures, is the presence of a true crepitus or impression which rubbing of the broken pieces together conveys to the hand or the ear.

This may be at once evident on manipulation, or auscultation, or only detected after much careful manoeuvring of the limb of the animal, or it may be altogether absent. In order to bring it about, an assistant should be instructed to move the leg carefully in various directions, inwards, outwards, backwards, and forwards, and to rotate it gently first in one direction and then in the other. During this time the hand or the ear of the examiner should be applied to the point of the ilium, and moved backward from place to place to the point of the buttock, the mind being at the same time concentrated upon it. The hand should then be passed into the rectum and brought into contact with every available part of the pelvis. Any crepitus occasioned by the movement will then be felt, and any swelling or displacement of the broken pieces at once recognized. Crepitus may sometimes be induced and recognized by pushing the animal over from one side to the other, while still keeping the hand on the quarter or in the rectum. The absence of crepitus and severe lameness does not always indicate the absence of fracture, but may be the result of no displacement of the broken bone having taken place.

In these cases of doubt the examination should be repeated day by day for several days, during which the patient must be kept perfectly quiet.

Treatment

The broken pelvis does not lend itself to those measures of mechanical restraint which are employed so successfully in dealing with some of the bones of the extremities, and we are therefore restricted in our endeavours to effect reparation to the device of slinging and maintaining as nearly as possible an upright posture, thereby avoiding those disturbing-efforts involved in lying down and rising again, movements which are sometimes attended with most disastrous results.

Whether treatment is likely to be attended with success or not is a question which the examiner must answer for himself after having made a searching examination.

Generally it may be said that, owing to the very imperfect control which can he exercised over the movements of the horse, and the disturbing effect of the weight of the body acting on the broken bones while in the upright posture, but little can be hoped for from treatment.

In fracture of the acetabulum there is only a very remote prospect of a reunion of the broken pieces being brought about, and much the same may be said of a breach in the floor of the pelvis. We have seen instances of repair in both these fractures, but they are very rare indeed, and in the former case severe lameness continued throughout life.

The external angle of the ilium is frequently broken and displaced more or less in a downward direction without materially affecting the patient's usefulness. In these cases a replacement of the broken fragments cannot be effected owing to the downward pull of the muscles attached to it, but it continues to be connected to the part from which it was torn by a strong band of connective tissue, and the patient suffers only a temporary inconvenience from the accident. Here rest is all that is needed to bring about a satisfactory result.

Less frequently, but in a large proportion of cases, the same good result follows under the same simple course of treatment when the internal angle is broken.

Some prospect of recovery offers, where the fracture involves only the neck of the ilium, so long as there is no displacement, and the same remark applies where the point of the ischium is broken; but it frequently occurs that the parts break away in the course of repair, before it has sufficiently advanced to keep them in position.

Except in those forms of fracture last referred to, unless some special value be attached to the injured animal for stud purposes, the desirability of prompt destruction should be well considered. Experience teaches that in the most favourable cases, where reunion of the broken pieces is complete, some deformity of the pelvis, some irreparable interference with nerves or vessels, or wasting of muscles, is left behind to cripple the patient after long and costly nursing.

Perfect quietude as far as it can be enforced is the one condition to be aimed at, and this will be best secured by placing the animal in slings. In doing so it should be observed that the ground is not slippery, and that it is well covered with peat-moss or saw-dust, or, failing these, a thick covering of sand. Peat-moss being the softest, most adhesive, and least likely to jar the limb, is to be preferred. It may be that the patient may experience some difficulty for a time in emptying the bladder, owing to being unable to extend himself. In such cases the urine must be withdrawn by means of the catheter with as little disturbance to the horse as possible. Brisk friction or rubbing with a brush over the legs and quarter will tend to relieve stiffness and afford comfort while under restraint.

A diet composed of bran and roots, with a moderate amount of hay, chaff, and a few crushed oats, is the most suitable, and two table-spoonfuls of linseed-oil incorporated with it three or four times a week will serve to keep the bowels regular. Everything should be done to minister to the comfort of the animal, and time must do the rest.