230 HORSE, SWINE AND POULTRY DISEASES 



behind the shank bone. It is round and smooth, but not so regularly 

 formed as the bog spavin, and is most apparent when viewed from 

 behind. The swelling is usually on both sides and a little in front 

 of the so-called hamstring, but may be more noticeable on the inside 

 or on the outside. 



In their general characteristics bog spavins and thoroughpins 

 are similar to windgalls, and one description of the origin, symp- 

 toms, pathological changes, and treatment will serve for all equally, 

 except that it is possible for a bog spavin to cause lameness, and thus 

 to involve a verdict of unsoundness in the patient, a circumstance 

 which will, of course, justify its classification by itself as a severer 

 form of a single type of disease. We have already referred to the 

 subject of treatment and the means employed rest, of course with 

 liniments, blisters, etc., and what we esteem as the most active and 

 beneficial of any, early, deep, and well-performed cauterization. 



OPEN JOINTS, BROKEN KNEES, SYNOVITIS, AND ARTHRITIS. 



The close relationship which exists among these several affec- 

 tions, their apparently possible connection as successive develop- 

 ments of a similar, if not an essentially identical, origin, together 

 with the advantage gained by avoiding frequent repetitions in the 

 details of symptoms, treatment, etc., are our reasons for treating 

 under a single head the ailments we have grouped together in the 

 present section. 



Cause. The great, comprehensive, common cause of, sometimes 

 permanent, sometimes only transient, disability of the horse is exter- 

 nal traumatism. Blows, bruises, hurts by nearly every known form 

 of violence, falls, kicks, lacerations, punctures we may add compul- 

 sory speed in racing and cruel overloading of draft animals cover 

 the entire ground of causation of the diseases and injuries of the 

 joints now receiving our consideration. In one case, a working horse 

 making a misstep stumbles, and falling on his knees receives a hurt, 

 variously severe, from a mere abrasion of the skin to a laceration, a 

 division of the tegument, a slough, mortification, and the escape of 

 the synovial fluid, with or without exposure of the bones and their 

 articular cartilages. 



In another case, an animal, from one cause or another, perhaps 

 an impatient temper, has formed the habit of striking or pawing his 

 manger with his fore feet until inflammation of the kneejoint is 

 induced, first as a little swelling, diffused, painless ; then as a perios- 

 titis of the bones of the knee ; later as bony deposits, then lameness, 

 and finally ^the implication of the joint, with all the various sequela? 

 of chronic inflammation of the kneejoint. 



In another case, a horse has received a blow with a fork from a 

 careless ^hostler on or near a joint, or has been kicked by a stable 

 companion, with the result of a punctured wound, at first mild- 

 looking, painless, apparently without inflammation, and not yet caus- 

 ing lameness, but which, in a few hours, or it may be only after a 

 few days, becomes excessively painful, grows worse, the entire joint 

 swells, presently discharges, and at last a case of suppurative synovitis 

 is presented, with perhaps disease of the joint proper, and arthritis 



