Part 58

Symptoms.—In the earlier stages of the disease, if inflammation is present, the only evidence of the trouble to be detected is a little fever over the seat of the affected cartilage and a slight lameness. In the lameness of sidebones the toe of the foot first strikes the ground and the step is shorter than natural. The subject comes out of the stable stiff and sore, but the gait is more free after exercise.

Since the deposit of bony matter often begins in that part of the cartilage where it is attached to the coffin bone, the diseased process may exist for some time before the bony growth can be seen or felt. Later, however, the cartilage can be felt to have lost its elastic character, and by standing in front of the animal a prominence of the coronary region at the quarters can be seen. Occasionally these bones become so large as to bulge the hoof outward, and by pressing on the joint they so interfere with locomotion that the animal becomes entirely useless.

Treatment.—So soon as the disease can be diagnosed active treatment should be adopted. Cold-water bandages are to be used for a few days to relieve the fever and soreness.

The improvement consequent on the use of these simple measures often leads to the belief that the disease has recovered; but with a return to work the lameness, fever, etc., reappears. For this reason the use of blisters, or, better still, the firing iron, should follow on the discontinuance of the cold bandages.

But in many instances no treatment will arrest the growth of these bony tumors, and as a palliative measure neurotomy must be resorted to. Generally this operation will so relieve the pain of locomotion that the patient may be used for slow work; but in animals used for fast driving or for saddle purposes, the operation is practically useless. Some years ago at Fort Leavenworth I unnerved a number of cavalry horses that were suffering from sidebones, and the records show that in less than seven months all were more lame than ever. Since a predisposition to develop sidebones may be inherited, animals suffering from this disease should not be used for breeding purposes unless the trouble is known to have originated from an accident.

RINGBONE.

A ringbone is the growth of a bony tumor on the ankle. This tumor is, in fact, not the disease, but simply the result of an inflammatory action set up in the periosteum and bone tissue proper of the pastern bones. (Plate XXXIV, fig. 1.) (See also p. 313.)

Causes.—Injuries, such as blows, sprains, overwork in young, undeveloped animals, fast work on hard roads, jumping, etc., are among the principal exciting causes of ringbone. Horses most disposed to this disease are those with short, upright pasterns, for the reason that the shock of locomotion is but imperfectly dissipated in the fore legs of these animals. Improper shoeing, such as the use of high calks, a too great shortening of the toe and correspondingly high heels, predispose to this disease by increasing the concussion to the feet.

Symptoms.—The first symptom of an actively developed ringbone is the appearance of a lameness more or less acute. If the bony tumor forms on the side or upper parts of the large pastern, its growth is generally unattended with acute inflammatory action, and consequently produces no lameness or evident fever. These are called "false" ringbones. But when the tumors form on the whole circumference of the ankle, or simply in front under the extensor tendon, or behind under the flexor tendons, or if they involve the joints between the two pastern bones, or between the small pastern and the coffin bone, the lameness is always severe. These constitute the true ringbone. Besides lameness, the ankle of the affected limb presents more or less heat, and in many instances a rather firm, though limited, swelling of the deeper tissues over the seat of the inflammatory process. The lameness of ringbone is characteristic in that the heel is first placed on the ground when the disease is in a fore leg, and the ankle is kept as rigid as possible. In the hind leg, however, the toe strikes the ground first, when the ringbone is high on the ankle, just as in health, but the ankle is maintained in a rigid position. If the bony growth is under the front tendon of the hind leg, or if it involves the coffin joint, the heel is brought to the ground first. In the early stages of the disease it is not always easy to diagnose ringbone, but when the deposits have reached some size they can be felt and seen as well.

The importance of a ringbone depends on its seat and often on its size. If it interferes with the joints or with the tendons it may cause an incurable lameness, even though small. If it is on the sides of the large pastern, the lameness generally disappears as soon as the tumor has reached its growth and the inflammation subsides. Even when the pastern joint is involved, if complete anchylosis results, the patient may recover from the lameness with simply an imperfect action of the foot remaining, due to the stiff joint.

Treatment.—Before the bony growth has commenced the inflammatory process may be cut short by the use of cold baths and wet bandages, followed by one or more blisters. If the bony deposits have begun, the firing iron should always be used. Even when the tumors are large and the pastern joint involved, firing often hastens the process of anchylosis and should always be tried.

When the lower joint is involved, or if the tumor interferes with the action of the tendons, recovery is not to be expected. In many of these latter cases, however, the animal may be made serviceable by proper shoeing. If the patient walks with the toe on the ground, the foot should be shod with a high-heeled shoe and a short toe. On the other hand, if he walks on the heel, a thick-toed and thin-heeled shoe must be worn.

Since ringbone is considered to be one of the hereditary diseases, no animal suffering from this trouble should ever be used for breeding purposes.

LAMINITIS, OR FOUNDER.

Laminitis is a simple inflammation of the sensitive laminae of the feet, characterized by the general phenomena attending inflammation of the skin and mucous membranes, producing no constitutional disturbances except those dependent upon the local disease, and having a strong tendency, in severe cases, to destructive disorganization of the tissues affected.

Causes.—The causes of laminitis are as wide and variable as in any of the local inflammations, and may be divided into two classes—the predisposing and the exciting.

Predisposing causes.—From personal observation I do not know that any particular construction of foot or any special breed of horses is predisposed to this disease, neither can I find anything to warrant the assumption that it is in any way hereditary; so that while we may easily cultivate a predisposition to the disease, it does not originate without an exciting cause. Like most other tissues, a predisposition to inflammation may be induced in the sensitive laminae by any cause which lessens their power of withstanding the work imposed on them. It exists to an extent in those animals unaccustomed to work, particularly if they are plethoric, and in all that have been previous subjects of the disease, for the same rule holds good here that we find in so many diseases—i. e., that one attack impairs the functional activity of the affected tissues and renders them more easy of a subsequent inflammation. Unusual excitement by determining an excessive blood supply, bad shoeing, careless paring of the feet by removing the sole support, and high calkings without corresponding toe pieces must be included under this head.

Exciting causes.—The exciting causes of laminitis are many and varied. The most common are concussion, overexertion, exhaustion, rapid changes of temperature, ingestion of certain feeds, purgatives, and the oft-mentioned metastasis.

(1) Concussion produces this disease by local overstimulation. The excessive excitement is followed by an almost complete exhaustion of the functional activity of the laminated tissues, the exhaustion by congestion, and eventually by inflammation. But congestion here, as in all other tissues, is not necessarily followed by inflammation; for, although the principal symptoms belonging to true laminitis are present, the congestion may be relieved before the processes of inflammation are fully established. This is the condition in the many so-called cases of laminitis which recover in from 24 to 48 hours. They should be called congestion of the laminae.

Laminitis from concussion is common in trotting horses that are raced when not in condition, especially if they carry the obnoxious toe weights, and in green horses put to work on city pavements to which they are unaccustomed. Concussion from long drives on dirt roads is at times productive of the same results, notably when the weather is extremely warm, or at least when the relative change of temperature is great. But the exhaustion of these circumstances must prove an exciting cause as well as the long-continued concussion. This combination of causes must also determine the disease at times in hunters, for the weight of the rider increases the demands made upon the function of these tissues, and their powers are the sooner exhausted.

(2) Overexertion, as heavy pulling or rapid work, even when there is no immoderate concussion, occasionally results in this disease. Here also exhaustion is a conjunctive cause, for overexertion can not be long continued without exhaustion.

(3) Exhaustion is nearly as prolific a source of laminitis as is concussion, for when the physical strength is impaired, even though temporarily, some part of the economy is rendered more vulnerable to disease than others. To this cause we must ascribe those cases which follow a hard day's work, in which at no time has there been overexertion or immoderate concussion.

The tendency to laminitis in horses on sea voyages results from the continual constrained position the animal maintains on account of the rocking motion of the vessel.

If one foot has been blistered, or if one limb is incapacitated from any cause, the opposite member, doing double duty, soon becomes exhausted, and congestion, followed by inflammation, results. When one foot only becomes laminitic, it is customary to find the corresponding member participating at a later date; not always because of sympathy, but because one foot had to do the work of two.

(4) Rapid changes of temperature act as an exciting cause of laminitis by impairing the normal blood supply.

This change of temperature may be induced by drinking large quantities of cold water while in an overheated condition. Here the internal heat is rapidly reduced, the neighboring tissues and blood vessels constrained, and the blood supply to these organs greatly diminished, while the quantity sent to the surface is correspondingly increased. True, in many cases there has not been sufficient labor performed to impair the powers of the laminae, and laminitis is more readily induced than congestion or inflammation of the skin or other surface organs, because the laminae can not relieve themselves of threatened congestion by the general safety valve of perspiration. A cold wind or relatively cold air allowed to play upon the body when heated and wet with sweat has virtually the same result, for it arrests evaporation and rapidly cools the external surface, thereby determining an excess of blood to such organs and tissues as are protected from this outside influence. In many instances this happens to be some of the internal organs, as the lungs, if the previous work has been rapid and their functional activity impaired; but in numerous other instances the determination is toward the feet, and that it is so depends upon two very palpable facts: First, that these tissues have been greatly excited and are already receiving as much blood as they can accommodate consistently with health; second, even though these tissues are classed with those of the surface, their protection from atmospheric influences by means of the thick box of horn incasing them renders them in this respect equivalent to internal organs.

A more limited local action of cold may excite this disease, by driving through water or washing the feet and legs while the animal is warm or just in from work. Here a very marked reaction takes place in the surface tissues of the limbs, and passive congestion of the foot results from an interference with the return flow of blood which is being sent to these organs in excess. These are more liable to be simple cases of congestion, soon to recover, yet they may become true cases of laminitis.

(5) Why it is that certain kinds of grain will cause laminitis does not seem to be clearly understood. Certainly they possess no specific action upon the laminae, for all animals are not alike affected; neither do they always produce these results in the same animal. Some of these feeds cause a strong tendency to indigestion, and the consequent irritation of the alimentary canal may be so great as to warrant the belief that the laminae are affected through sympathy. In other instances there is no apparent interference with digestion nor evidence of any irritation of the mucous membranes, yet the disease is in some manner dependent upon the feed for its inception. Barley, wheat, and sometimes corn are the grains most liable to cause this disease. With some horses there appears to be a particular susceptibility to this influence of corn, and the use of this grain is followed by inflammation of the feet, lasting from a few days to two weeks. In these animals, to all appearances healthy, the corn neither induces colic, indigestion, nor purging, and apparently no irritation whatever of the alimentary canal.

(6) Fortunately purgative medicines rarely cause inflammation of the laminae. That it is, then, the result of sympathetic action is no doubt more than hypothetical, for when there is no derangement of the alimentary canal a dose of cathartic medicine will at times bring on severe laminitis.

(7) Almost all the older authorities were agreed that metastatic laminitis is a reality. In my opinion metastatic laminitis is nothing more nor less than concurrent laminitis, and presents little in any way peculiar outside the imperfectly understood exciting cause. The practitioner who allows the acute symptoms of the laminitis to mislead him, simply because their severity has overshadowed those of the primary disease, may lose his case through unguarded subsequent treatment. This form of laminitis is by no means commonly met with. It may be found in conjunction with pneumonia, according to Youatt with inflammation of the bowels and eyes, and according to Law and Williams sometimes with bronchitis.

Symptoms.—Laminitis is characterized by a congregation of symptoms so well marked as scarcely to be misinterpreted by the most casual observer. They are nearly constant in their manifestations, modified by the number of feet affected, the cause which has induced the disease, the previous condition of the patient, and the various other influences which to some extent operate in all diseases. They may be divided into general symptoms, which are concomitants of all cases of the disease, subject to variations in degree only, and special symptoms, or those which serve to determine the feet affected and the complications which may arise.

General symptoms.—Usually, the first symptom is the interference with locomotion. Occasionally the other symptoms are presented first. As the lameness develops the pulse becomes accelerated, full, hard, and strikes the finger strongly; the temperature soon rises several degrees above the normal, reaching sometimes 106 deg. F.; it generally ranges between 102.5 deg. and 105 deg. F. The respirations are rapid and panting in character, the nostrils widely dilated, and the mucous membranes highly injected. The facial expression is anxious and indicative of the most acute suffering, while the body is more or less bedewed with sweat. At first there may be a tendency to diarrhea, or it may appear later as the result of the medicines used. The urine is high colored, scant in quantity, and of increased specific gravity, owing to the water being eliminated by the skin instead of the kidneys. The appetite is impaired, sometimes entirely lost, but thirst is greatly increased. The affected feet are hot and dry, and as much as possible are relieved from bearing weight. Rapping them with a hammer, or compelling the animal to stand upon one affected member, causes intense pain. The artery at the fetlock throbs beneath the finger.

Special symptoms.—Liability to affection varies in the different feet according to the exciting cause. Any one or more of the feet may become the subject of this disease, although it appears more often in the fore feet than in the hind ones. This is due to the difference of the function, i. e., that the fore feet are the bases of the columns of support, receiving nearly all the body weight during progression and consequently most of the concussion, while the hind feet become simply the fulcra of the levers of progression, and are almost exempt from concussion.

One foot.—Injuries and excessive functional performance are the causes of the disease in only one foot. The general symptoms, as a rule, are not severe, there being often no loss of appetite and no unusual thirst, while the pulse, temperature, and respiration remain about normal. The weight of the body is early thrown upon the opposite foot, and the affected one is extended, repeatedly raised from the floor, and then carefully replaced. When made to move forward the lame foot is either carried in the air while progression is accomplished by hopping with the healthy one, or else the heel of the first is placed upon the ground and receives little weight while the sound limb is quickly advanced. Progression in a straight line is more easy than turning toward the lame side.

Both fore feet.—When both fore feet are affected the symptoms are well marked. The lameness is excessive and the animal almost immovable. When standing the head hangs low down, or rests upon the manger as a means of support and to relieve the feet; the fore feet are well extended so that the weight is thrown upon the heels, where the tissues are least sensitive, least inflamed, and most capable of relief by free effusion. The hind feet are brought forward beneath the body to receive as much weight as possible, thereby relieving the diseased ones. If progression is attempted, which rarely happens voluntarily during the first three or four days, it is accomplished with very great pain and lameness at the starting, which usually subsides to an extent after a few minutes' exercise. During this exercise, if the animal happens to step upon a small stone or other hard substance, he stumbles painfully and is excessively lame in the offended member for a number of steps, owing to the acute pain which pressure upon the sole causes in the tissues beneath. The manner of the progression is pathognomonic of the complaint. Sometimes the affected feet are simultaneously raised from the ground (the hind ones sustaining the weight), then advanced a short distance and carefully replaced; at almost the same moment the hind ones are quickly shuffled forward near to the center of gravitation.

In other instances one foot at a time is advanced and placed with the heel upon the ground in the same careful manner, all causes of concussion being carefully avoided. In attempting to back the animal he is found to be almost stationary, simply swaying the body backward on the haunches and elevating the toes of the diseased feet as they rest upon their heels. In attempting to turn either to the right or left he allows his head to be drawn to the one side to its full extent before moving, then makes his hind feet the axis around which the forward ones describe a shuffling circle.

In most of cases of laminitis in the fore feet the animal persists in standing until he is nearly recovered. In other cases he as persistently lies, standing only when necessity seems to compel it, and then for as short a time as possible. If the recumbent position is once assumed, the relief experienced tempts the patient to seek it again; so we often find him down a greater part of the time. But this is not true of all cases; sometimes he will make the experiment, then cautiously guard against a repetition. Even in cases of enforced recumbency, he ofttimes takes advantage of the first opportunity and gets upon his feet, doggedly remaining there until again laid upon his side. How to explain this diversity of action I do not know; theoretically the recumbent position is the only appropriate one, except when complications exist, and the one which should give the most comfort, yet it is rejected by very many patients and, no doubt, for some good reason. It has been suggested as an explanation that when the animal gets upon his feet after lying for a time the suffering is so greatly augmented that the memory of this experience deters him from an attempted repetition. If this were true, the horse with the first attack must necessarily make the experiment before knowing the after effects of lying down, yet many remain standing without even an attempt at gaining this experimental knowledge.