SYMPTOMS OF ACUTE ARTICULAR RHEUMATISM IN THE HORSE.
Chill, hyperthermia, lameness in fetlock, hock, knee, shoulder, stifle, hip, elbow, tendons, sheaths, bursæ, bilateral, shifting, swelling, heat, tenderness, decubitus, joint semi-flexed, pain on extension or flexion, signs of cardiac disease. Course: rapid to recovery, improvements and relapses, metastasis, debility.
The attack is usually sudden and marked by a slight chill, shivering or staring coat with hyperthermia and lameness. The temperature may vary from normal to 107° or 108° F. in severe attacks. In many cases the fever and lameness appear simultaneously, the former being in ratio with the extent and severity of the latter, but not infrequently the elevation of temperature precedes the articular symptoms, and then it is to be considered as concurrent with the internal lesions—cardiac, pericardial or otherwise. In other cases the articular lesions and lameness precede by several days the appearance of the fever. So far as we know the fever never antedates the occurrence of some local lesion, external or internal.
The joints affected are very varied. The fetlock is the most frequently attacked, but some of the other larger joints, the hock, knee, shoulder, stifle, hip and elbow are often involved or exclusively affected. The adjacent tendons and their synovial sheaths are very often implicated; the attack is very prone to show a bilateral symmetry, the same joints (right and left) on the corresponding fore or hind limbs, suffering at once, or, as in the case of the fetlocks, all four are simultaneously attacked. A joint that is weak by reason of previous injury or disease is especially liable to suffer, and is then less likely than joints that had been previously healthy to undergo speedy improvement. When the symptoms wander from joint to joint or from joint to muscle, or fascia or tendon, the disease in its earlier seat seeming to undergo almost complete resolution, while it advances with great intensity in the newly affected joint or part, the occurrence is highly significant. These transitions often take place with great rapidity. Thus the centre of suffering may shift from one joint to another in an hour, (Megnin, Cadeac), or from a limb to the loins in a quarter of an hour (Lewis). The fact that the inflammation remains fixed in one or several joints, is not, however, proof of the absence of rheumatism. A joint with a primary weakness or injury may remain the seat of disease through even a chronic rheumatism.
The affected joint is usually swollen, hot and tender; the tenderness being as a rule greatest where the capsular ligament is pressed upon. These symptoms are very evident in joints that approach the surface, and obscure in such as are thickly covered by muscle (shoulder, hip). The swelling is soft, or tense and elastic (especially over the synovial membrane), or œdematous and pitting on pressure. On white skins sparsely covered by hair there is marked redness and congestion, the veins standing out prominently and the arteries above the joint pulsating strongly. When the tendinous sheaths are involved, they stand out as elastic lines following the course of the tendons, and with more or less pasty swelling adjacent.
In some cases, however, the swelling may be entirely absent, and the trouble is to be located only by the local tenderness and pain during motion.
Small, hard, pea like, subcutaneous nodosities were first noticed by Floriep, in 1843, in rheumatism in man, and have been met with in different cases in the horse. Rodet fils met with great numbers of these nodules crepitating under pressure, in a horse that had suffered for months from chronic rheumatism.
Acute pain on moving the affected joint or tendon is a most characteristic symptom. The horse goes dead lame, walks on three legs, or with great stiffness, and avoids as far as possible all flexion of the joint. If left alone the animal stands stock still, never moving from the place, or in the worst cases lies down and refuses to rise. If compelled to walk his suffering is shown by hastened breathing, dilated nostrils, anxious, pinched countenance and low plaintive neighing. The affected joint is held semi-flexed, to relieve the tension, the pastern is habitually more upright, and if the foot is lifted and the affected joint bent or extended, the animal winces, or resists, and tries to draw away the limb and groans. The movements of the affected joint in walking or under manipulation, are often attended by cracking which may be both felt and heard. It has been variously attributed to lack of synovial lubrication (Cadeac), and ulceration of the articular cartilage (Lafosse), yet it may occur from the constrained position assumed, as in the case of a man attempting to walk noiselessly on tip toe, and in other cases from the extension of false membranes, or of rigid or contracted binding ligaments.
Rheumatism of the fetlock and sesamoid pulley, as the most common form in solipeds, demands a special notice. The swelling of one fetlock, of the two fore, of the two hind or of all four at once, extends beyond the limits of both joint and sesamoid pulley and may form a general engorgement or stocking which serves to hide the synovial distension. Pressure however shows that while all is tender, the extreme tenderness is referable to the joint, the synovial sheath of the flexors, to the flexors or suspensory ligaments. As the general swelling subsides the rounded or ovoid synovial distensions become more patent. The swelling and tenderness may extend to the knee in which case the synovial membrane of the carpal arch is especially distended and tender from the carpus down, or in the hind limb the synovial membrane of the tarsal arch is distended showing in this case on the inner and outer sides in front of the calcis, and not infrequently implicating the summit of that bone as a capped hock.
In rheumatism of the shoulder the coraco-radial tendon and pulley may be involved, causing a diffuse swelling on the point of the shoulder. If the hip is the seat of disease the median gluteal may suffer, causing an indefinite swelling over the joint. If the stifle is affected the patellar capsule suffers and not infrequently the tendon and pulley of the flexor metatarsi are involved.
The most important internal complications, pericarditis and endocarditis, are manifested by their usual symptoms, sharp, variable, irregular, unequal or intermittent pulse, blowing murmur usually with the first heart sound, oppressed breathing, and it may be muffled heart sounds, or dropsies.
Course. This is exceedingly uncertain. Some cases make a rapid progress to complete convalescence; others make partial improvements interrupted by relapses; others have the morbid process subside in great measure in one joint or organ only to reappear in full force in another; others leave complications on the part of the heart especially and are rendered permanently useless. Even should the heart escape, the health often suffers so much in connection with the destruction of the red globules, the malnutrition, and the local disease, swellings and distortions of the joints that a perfect recovery seems distant and problematical.