402 Veterinary Medicine. 



Ovination or inoculation with the lymph of sheeppox is the 

 only accepted method of immunization. It entails, however, an 

 extraordinary multiplication of the virus in each inoculated ani- 

 mal, and considering the numerous loopholes for its possible dif- 

 fusion it can only be looked on as a very dangerous and usually, 

 in the long, run, a very expensive resort. The experience of 

 England, above referred to, is eloquent in witnessing against 

 ovination, and ' ' in Prussia and Austria the dissemination of 

 sheeppox went hand in hand with inoculation. " — Friedberger and 

 Frohner. 



On the other hand ovination is not fatal to the flock operated 

 on. The mortality is often below i per cent., and virtually never 

 exceeds 4, with a general average of about 2 per cent. It is this 

 comparative impunity of the inoculated flock which closes the eyes 

 of most persons to the great danger to a whole country and the 

 wasteful prodigality of the operation. 



Ovination further shortens the duration of the outbreak in a 

 large flock, passing all through the disease in 21 days; whereas 

 as contracted bj' simple exposure, the duration of the outbreak 

 may last 90 days or more. It further enables the owner to give 

 such protection, shelter and care as will guard the flock against 

 exposure and dangerous complications. But while preferable to 

 the abandoning of the disease to its natural course, it is always to 

 be strongly condemned where it is possible to adopt the method 

 which detects the sick animal in the incipient stage by thermometry, 

 and does away with the infection by its removal, followed by dis- 

 infection. The only excuse for ovination is the general preva- 

 lence of sheeppox on an island or other secluded district where 

 there is no great added danger from the further diffusion of the 

 virus, and when its simultaneous practice over the whole region 

 can be made the basis for universal disinfection and the definite 

 extinction of the contagium. 



Technique of Ovination. The lymph ("ovine") should be 

 taken from a mild case of the disease, and from a vesicle at full 

 maturity (about the 6th day), but containing as yet a clear, 

 translucent exudate, without turbidity or other indication of for- 

 mation of pus, or other infection. Inoculation is made by prefer- 

 ence on the bare lower surface of the tail near its tip or 3 to 4 

 inches behind the anus. If this is unsuitable, the inner side of 



