My mare was bred on 7/11 and 7/13. Ultrasound on 7/28 pregnant.  When can I safely wormer and which wormer would be safe to use. I haven't had a mare in foal for 6 years and I don't remember .   Thanks

I would be asking your Vet this question. And what type of dewormer to use also.

for the first 30 days I wont do anything that might upset the pregnancy.  After that, its all fair game, I use Zimectrin Gold for the summer de-worm.

Agree... My vet said it was ok to worm my mare (bred in April) when I asked him in July.  

:)