566 Veterinary Medicine. 



more subject to injury from excess of uric acid and allied 

 products. Birds at this age, confined and in process of fattening 

 are thereby exposed. Overfed, obese, lazy, old house dogs are' 

 under similar causative conditions. 



Lesions. The most prominent lesions in birds are chalky con- 

 cretions of urates on the articular ends of the bones and in the 

 structures around the joints including even the tendons, with 

 more or less inflammatory exudate and even necrosis, invading 

 the bony tissue and articular cartilage. Abscesses maybe present 

 usually outside the bursa. Birds suffer especially in the tarsal, 

 metatarsal and phlangeal joints, but often also in the correspond- 

 ing joints of the wing, and less frequently in the joints of the 

 trunk, and in the internal organs, — kidneys, liver, lungs, serosse — 

 and skin. In these last, miliary chalky concretions and encrusta- 

 tions are found. In Briickmiiller's case in the dog the chalky 

 deposits of urates were found mainly on the epiphyses of the ribs, 

 but also on the joints of the limbs. 



Uric acid is always abundant in the blood of birds, and Roberts 

 has shown that biurate of soda (the, usual form of precipitate) is 

 insoluble in blood serum, synovia and other body- fluids when in 

 excess of i : 10,000. 



Symptoms. In birds the febrile and constitutional symptoms 

 have not been carefully observed so that the objective symptoms 

 in the affected joints have been mainly relied on. There is 

 extreme tenderness marked by standing on one limb, or resting 

 on the breast, and hence moping apart from the flock. When 

 made to rise, the affected limb may be used to steady the body, or 

 even to walk, with a limp, though in bad cases the sound limb 

 only may be used. The affected joints are swollen, soft, hot, 

 extremely tender, pitting on pressure, and later the seat of 

 nodular yellow masses, usually hard, but sometimes fluctuating 

 and in size from a pea to a hazel nut. The superimposed 

 epidermis is thick, dry and scaly, falling off in flakes. At a more 

 advanced stage the concretions may burst through the skin, dis- 

 charging a buffy, granular, debris containing crystals of urates of 

 ammonium or calcium, or of uric acid. I^ater still are ulcerous 

 sores, involving the disintegrating urate nodules and the necrotic 

 bones and cartilages. The deposits deflect the bones from their 

 normal direction, causing not only nodular swellings on the toes 



