282 HEALTH AND DISEASE 



such an operation depends upon the complete control and obedience of the 

 patient, which cannot be obtained in the horse. 



SYNOVITIS— INFLAMMATION OF THE SYNOVIAL 



MEMBRANE 



When the lining membrane of a free-moving joint becomes inflamed, 

 the disease is known as synovitis. 



The attack may be acute or severe, subacute, or chronic, in which last 

 case it continues for a more or less protracted period. The first and second 

 forms may become resolved into the third. 



Causes. — Synovitis is for the most part induced by blows, sprains, and 

 penetrating wounds; or it may follow upon exposure to cold and wet; or 

 arise in the course of an attack of pyaemia, or after the ingestion of food or 

 water contaminated with lead or copper smoke. 



ACUTE SYNOVITIS 



This form of the disease most frequently results from wounds which 

 injure or puncture the capsule of the joint, and especially such as are con- 

 taminated with septic matter at the time of or after infliction. 



The size of the wound is no measure of the danger which may attend it. 

 A dirty stable-fork entering a joint may prove as destructive as a wound 

 inches in length. Pysemia is a common cause of acute synovitis in foals, 

 and less frequently in young horses when suftering from strangles. 



Severe blows and sprains, and acute attacks of rheumatism, especially 

 when following upon influenza, are also fruitful causes of it. 



Symptoms. — Lameness more or less severe is the first noticeable 

 symptom of the disease. The joint becomes distended with s3'novia, and 

 bulges at points where there is least resistance. The swelling thus formed 

 is tense and fluctuating, and when pressed acute pain is evinced. Soon the 

 outer structures of the joint become enlarged, hot, and tender. The animal 

 stands with the leg in a semi-flexed condition, imposing little or no weight 

 on it. The local suffering soon gives rise to constitutional disturbance, 

 attended with considerable fever and prostration. 



As the disease progresses the joint becomes filled with pus, the inflam- 

 mation spreads to structures round and about it, one or more abscesses 

 form and break, and the purulent contents of the joint escape. 



In those cases where joint abscess develops, the articular cartilage 

 undergoes softening and displacement, and the underlying bone becomes 

 exposed and diseased. In such circumstances the function of the joint is 



