720 Diseases of the Genital Organs 



nant ewe can be made to abort during her existing preg- 

 nancy by inoculating with vibrio or other organism is cer- 

 tainly far from conclusive. The complexity of experimen- 

 tal proof is essentially the same as in cattle, which has been 

 considered at length. 



Opportunity was afforded me and my colleague, Car^ 

 penterS for a brief study of a disease affecting pregnant 

 ewes, many of which aborted. The owner made a practice 

 of purchasing Western ewe lambs (that is, lambs grown up- 

 on the Rocky Mountain plateau) in the stockyard at Chi- 

 cago or Buffalo, securing purebred rams, breeding them' for 

 two years, marketing the lambs, and finally the matured 

 ewes. The operations had been remunerative and success- 

 ful. 



In 1917 he purchased 252 ewe lambs and imported from 

 Canada four purebred Shropshire ram lambs as sires. This 

 gave to each ram 59 females, involving an average minimum 

 of 3 ewes in estrum each day for each ram. The result was 

 209 lambs, or an increase of 89 per cent., which indicated 

 reasonable sexual health. The ideal ratio would have been 

 at least 11 per cent, higher. The same rams were used the 

 next year, no new sheep of either sex having been added. So 

 far as known there was, with one exception, no contact with 

 other sheep. Moreover all neighboring flocks, so far as could 

 be learned, were healthy. The one exception as to contact 

 was that, a few days prior to the intended breeding opera- 

 tions, a Tunis ram broke into the premises and copulated 

 with some of the ewes. Twelve of these, all so far as known 

 that copulated with the Tunis ram, gave birth to 13 cross- 

 bred lambs, all of which lived. There remained, according 

 to the caretakers, 223 ewes, which were bred to the same 

 Shropshire rams used the previous pear. When pregnancy 

 in these had become sufficiently advanced to render the ex- 

 pulsion of fetal cadavers obvious, abortions began to be ob- 

 served. The 223 ewes bred to the Shropshire rams pro- 

 duced 127 viable lambs (57 per cent.) Some ewes which 

 failed to produce lambs were not observed to expel fetal 



iReportN. Y. State Veterinary College at Cornell Univ., 1918-19, page 125. 



