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398 Veterinary Obstetrics 



mare foal, and the shortest 318 days, a horse foal. The shortest 

 duration recorded by him was 298 days, the foal being a mare. 



Duration of Pregnancy in the Ass. 



Carsten-Harms gives the duration of pregnancy in the she-ass 

 as 348 to 377 days, which is in excess of the average duration in 

 the mare, but the observations which have been made are not 

 sufficient in number to render them very reliable. Various 

 writers claim that the period of gestation of mule foals is 

 greater than with horse foals. 



The Cow. The duration of gestation in the cow is usually 

 270 to 280 days, with a very wide variation. In 1062 cases 

 quoted by Fleming, 15 were pregnant less than 241 days, 52 from 

 241 to 270 days, 119 from 271 to 280 days, 544 from 271 to 300 

 days, 230 from 282 to 290 days, 70 from 290 to 300 days, and 32 

 beyond 301 days. Fleming gives the average duration at about 

 283 days, while Colin makes the average 280 to 285 days. 



The Sheep and Goat. The duration of pregnancy in the 

 sheep and goat is about 5 months, with variations of some 12 

 days. Some observers have found that the duration of gestation 

 was longer in female than in male lambs and there is an impres- 

 sion, which is apparently supported by statistics, that twins are 

 born somewhat earlier than single fetuses, but the difference, if 

 any exists, is very slight. 



The Sow. The duration of pregnancy in the sow is a trifle 

 short of four calendar months, or about 115 to 1 20 days, the 

 variation not being very great, although some authors give, as 

 extremes, about 104 to 127 days, with most births occurring be- 

 tween 115 and 125 days. 



Carnivora. The bitch is pregnant from 58 to 65 days, but 

 usually about 9 weeks or 63 days, while the duration of preg- 

 nancy in the cat is 3 or 4 days less, or about 8 weeks, with a 

 variation of 3 or 4 days. 



Wild Animals. 

 In wild ruminants, the duration of pregnancy varies from 34 

 or 35 to 40 weeks. Harms notes the peculiar fact that in the 

 deer there is a period of 40 weeks between impregnation and the 

 birth of the young, but that this time does not represent the 

 period of development of the fetus as we understand it in most 



