274 VETERINARY HYGIENE 



inoculation. The latter was used for pregnant animals, one dose 

 being given monthly until the sixth month. It was soon found, 

 however, that little good was derived from the use of Anti-abortion 

 B., and this was therefore discontinued. Stockman gives certain 

 statistics* which show beyond any possibility of error the very great 

 advantages accruing from the use of the living vaccine. Thus of 

 265 untreated animals in badly infected herds 38 per cent, aborted, 

 while of 493 vaccinated animals the number which aborted was 

 only 6.5 per cent. This method of vaccination has been put into 

 practice on a fairly considerable scale in Oxfordshire, and the 

 following statistics covering the period 1914-1916 show the results 

 with 1289 animals; of these 5.7 per cent, aborted against 20.7 per 

 cent, untreated controls. In 1913 30 per cent, aborted in this 

 county, f 



ENZOOTIC OVINE ABORTION. 



The causal organism of this disease is a motile vibrio 

 (M'Fadyean and Stockman). There is a certain amount of evid- 

 ence leading to the belief that it may exist as a saprophyte outside 

 the body. At present the disease may be said to be enzootic rather 

 than epizootic. As pointed out by Stockman, this is owing to the 

 fact that the cross trade in sheep is not carried on to the same 

 extent as with cattle, and that lambing is confined to a more definite 

 period of the year. Abortion usually follows infection much 

 earlier than is the case with bovines ; it may occur very soon after 

 infection or it may be delayed for several weeks (Stockman). 

 Though the vibrio is the specific organism of ovine abortion it may, 

 and sometimes does, cause abortion in cows. Indeed, recent 

 researches in America by Theobald Smith and collaborators have 

 shown that a similar or identical vibrio was present alone in nearly 

 24 per cent, of 109 cases of bovine abortion. The disease is mani- 

 fest usually within a few weeks after tupping has taken place. 

 Stockman gives the losses in infected flocks as from 10 to 40 per 

 cent$ Infection may take place either per os or per vaginwn, but 

 it hardly appears to be certain which is the more common natural 

 method. Stockman has shown that ewes can carry infection in 

 utero for considerable periods between pregnancies. If this view 

 is correct, the ram is probably one of the chief disseminators. 

 * Report to Tenth International Veterinary Congress. 



t Vet. Rev., 1917, Vol. I, p. 169. 

 $ Annual Report, C.V.O., Board of Agric., 1913, Cd, 7423. 



Annual Report, 1914, Cd, 8043. 



