280 HEALTH AND DISEASE 



another of the component structures, are the chief inducing factors. Frac- 

 tures, by extending into the joints, not only provoke in them acute and 

 dangerous disease, but so far damage and impair their action as seriously to 

 compromise further usefulness. AVouuds in connection with joints are of 

 especial difficulty and danger, not only on account of the joint having been 

 opened, but because of the entrance into it of septic organisms which excite 

 a suppurating or matter-forming process, first in one structure and then in 

 another, until all have become implicated. 



Of those constitutional conditions to which joint disease can be referred, 

 rheumatism offers a striking and by no means an uncommon example. 



Within sixty yards of where the writer now sits is a gray cob which, 

 while passing through an attack of influenza fever, suddenly became acutely 

 lame in both fore-limbs, so much so that her movements could only be 

 compared to those of an animal in the last stages of chi-onic navicular 

 disease. Every joint and sinew in the limbs was perfectly normal, but the 

 heat in the feet and the fulness in the heel clearly indicated some mischief 

 in the navicular joint, which was diagnosed as rheumatism. A blister was 

 applied over the coronets and the mare was turned to pasture, when she 

 became perfectly sound in three weeks. Rheumatism affecting the joints 

 and other structures presents itself also as a sequel of strangles and purpura. 



In that pysemic condition of foals known as "navel ill", the large joints 

 of the extremities frequently become distended with pus and serous exuda- 

 tion as the result of pysemic arthritis, and mares, after parturition, now and 

 again suffer from a similar affection, parturient synovitis. 



Inflammation of the lining membrane of the heart (endocarditis) is 

 sometimes associated with an abiding inflammation of the joints. 



All these possible causes require to be borne in mind when considering 

 the origin of joint disease. In numerous instances swelling of a joint, 

 resulting from " pyaemic arthritis" or "joint ill" in foals, has at first been 

 referred to a kick from the dam or other form of external violence, and 

 the error has only been recognized when other joints becoming affected 

 rendered the view no longer tenable. This leads us to point out that where 

 disease of the same nature attacks one joint after another in the same 

 animal, some constitutional cause should be suspected, whereas disease 

 confined to one joint only will usually be found to result from accident. 



The Local Origin of Joint Disease varies in different cases. It 



may first commence in the synovial membrane, or in the bone or the 

 cartilage. It does not, however, always confine itself to the structure in 

 which it originates, but frequently extends from one to another until all 

 are more or less involved. Sometimes the connecting ligaments will also 

 become affected and suffer with the rest in the morbid action. 



