SYMPTOMS OF CHRONIC ARTICULAR RHEUMATISM IN THE HORSE.
Larger joints, muscles, heart, false membranes, indurations, thickenings, calcifications, remittent, weather changes, cold, damp beds, winds, open windows or doors, draughts, cold sponging, clipping. Diagnosis: lameness variable, shifting, electric and meteoric storms.
Chronic rheumatism may be a sequel of the acute, or it may occur from the same causes acting with lessened force, or on a less susceptible animal. It tends to attack the larger joints especially, though it may implicate the muscles as well. Coincident affection of the heart is less common than in the acute, and when it does arise seems to advance slowly. It is liable to cause permanent distensions of the affected joint capsules, as well as false membranes, articular abrasions, degenerations and ulcerations and less frequently bony enlargements and calcifications, the latter implicating the soft tissues in the vicinity.
The attendant lameness is liable to be remittent or intermittent, subsiding in warm buildings and during genial, clear sunny weather, and relapsing in connection with cold, raw nights and mornings, exposure in the dew or rain, and before and during great changes of weather. Cold, damp beds, chilling draughts between open doors or windows, washing with iced water, sudden intense cooling of the body after perspiration, clipping during cold weather, any cause of sudden rigor, when followed by stiffness, lameness and articular swelling, serves to identify the latter as rheumatic. Even the warmth induced by judicious exercise, may cause improvement, so that a horse, starting out stiff or lame, may drive out of it after going a mile or two. The formation of subcutaneous nodules, though rare, appears to be more frequent than in acute rheumatism.
Diagnosis is to be based largely on the variability of the lameness at different times, its propensity to shift from place to place, its manifest association with exposure to cold, and with the immanence of electric storms or change in the barometric pressure, and its improvement under genial weather, warmth and comfort.