712 GANGRENOUS MAMMITIS. 



(6.) GANGRENOUS MAMMITIS OF MILCH EWES. 



Gangrenous mastitis is commonest in sheep, though it also occurs 

 in goats, but in the latter it does not take the enzootic form generally 

 seen in sheep. It was described in 1823 by D'Arboval, in 1856 by 

 Lafosse, and in 1875 by Rivolta, who is stated to have discovered 

 the causal micrococcus. The nature of the specific poison remained 

 uncertain until 1886-87, when Nocard isolated from the udder of a 

 sheep suffering from gangrenous mastitis a micrococcus, pure cultures 

 of which, injected into the mammary ducts of healthy sheep, always 

 reproduced the disease, but in other animals only caused slight 

 temporary swelling. Within the udder the specific micrococcus 

 produces toxins which cause necrosis of the tissues of the gland 

 accompanied by systemic toxaemia. 



Symptoms and Course. The disease starts as a peracute paren- 

 chymatous mammitis. Severe general symptoms, high fever, loss 

 of appetite, great weakness, pain, and a straddling gait first direct 

 attention to the udder. Local symptoms soon develop. The skin 

 of the affected gland exhibits redness, with bluish- violet or black 

 discrete spots, which on palpation are found to be soft, insensitive, 

 and very cold. These spots quickly coalesce forming necrotic patches. 

 They are surrounded by a crepitating inflammatory oedema which 

 extends along the abdomen, and even to the chest and thighs. Milk 

 secretion ceases, the lambs are hungry, and many of them suffer 

 from sores on the lips. Later, the affected ewes are constantly 

 down, groaning and grinding the teeth in acute pain, and after a 

 short interval, the temperature falls to below 98° or even 96° Fahr., 

 the animals show great prostration, with rapid, shallow breathing 

 and small or imperceptible pulse. Symptoms of toxaemia then 

 appear, and not infrequently death follows within twenty-four hours. 

 In exceptional cases the local process is limited. A dissecting inflam- 

 mation sets in which separates the necrotic tissues and may result 

 in recovery. This is, however, a very rare exception ; the greater 

 number of animals perish with symptoms of toxaemia. The disease 

 sometimes is complicated by septic metritis, which may either have 

 been produced simultaneously, or may even have occurred as the 

 primary condition, but for the time has escaped notice. 



The prognosis is unfavourable, for in many cases not even the 

 sacrifice of the udder can save the animal's life. Though some- 

 times the animals survive, they never regain their former condition, 

 but remain weak and unthrifty. 



Treatment. Segregation of the diseased sheep and disinfection 



