February 2, 2010 – PZP’s Effects, part 3: Out of Season Foals

I apologize for my delay in getting this post up; I didn’t have time to get this done during this past busy week.

It is very common to hear discussions on PZP treatments resulting in out of season foals. This will be the topic of today’s discussion.

Though there has been a great amount of speculation and large-scale reporting on PZP’s effect on the seasonality of foaling, this is a topic that has been discussed in few scientific studies. Kirkpatrick and Turner (2003) reported on the seasonality of foaling on Assateague Island among treated and untreated horses. They defined out of season foals as those foals not born in April, May, or June. Their study involved analysis of the times when 168 foals were born, from 1986 to 2002, along with whether the foals’ mothers had been untreated, treated for one year before a foal was born, or born after at least two consecutive years of treatment. The survival rate among foals born during different seasons to treated and untreated mares was also analyzed.


Published in: on February 2, 2010 at 11:30 am  Comments (5)