72 VACCINE AND SERUM THERAPY 



Immiimty. — A simple means of establishing im- 

 munity in the herd and in all newcomers is to 

 vaccinate the animals with calf lymph used for man. 

 The vaccination is carried out on the perineum by 

 superficially scarifying the skin. Nodules develop 

 on the affected cows, while on the healthy animals 

 typical pox pustules appear, and these animals do 

 not contract the infection. Personally, I have had 

 very excellent results from this procedure in herds 

 where the disease had been prevalent for years. 



Horse Sickness of South Africa.— This disease is 

 characterised as an acute or subacute disease of 

 solii^eds, and appears in epizootics during the hot 

 months of the year. The principal lesions are 

 oedematous swellings and hemorrhages of the internal 

 organs. 



Etiology. — McFadyean, in 1900, was the first to 

 show that this disease was caused by a filterable 

 virus. 



Immunisation against the disease may be estab- 

 lished by the use of serum from hyperimmunised 

 animals, or by the use of immune serum and virulent 

 blood. This latter method is advocated by Theiler ; 

 he injects 300 c.c. immune serum intravenously and 

 J c.c. virulent blood subcutaneously. Animals thus 

 treated will show a rise of temperature, upon which 

 a second injection of 50 to 100 c.c. eerum is made. 



