The prevention of pneumovagina and the effect of the Caslick operation on fertility: a retrospective study

Mares with a large vulvar orifice have an increased risk of pneumovagina, w hich is associated with reduced fertility. Treatment is by means of the Cas lick operation, by which size of the vulvar orifice is reduced. Factors tha t influence the occurrence of pneumovagina are the age and fertility static s of the mare. In this study the risk factors for pneumovagina and the effe ct of the Caslick operation on fertility were investigated. In 1994, 1995, and 1996 a total of 967 mares were sent for service at a stud. Of these mar es, 116 underwent a Caslick operation. The operated mares were older than t he non-operated mares. Mares younger than 5 years had a lower chance of pne umovagina than mares aged 5-12 years, but mares aged 13 and older had an in creased chance. Foals and barren mares were more likely than maiden mares t o develop pneumovagina. Fertility was 67% among the non-operated mares and 51% among the operated mares, even though, after the operation, the vulvar orifice of the operated mares was the same as that of the non-operated mare s. This difference infertility maybe due to secondary endometritis that con tinues to exist after the operation. Further research is needed to determin e whether mares with pneumovagina should also be treated for endometritis a t the time of surgery.