While the relative safety of doxycycline during early-stage pregnancy is yet unknown, Canisso said this study demonstrates that this drug could be a safe and viable option for treating infections, including placentitis, in late-term mares. | Photo: Thinkstock

Doxycycline has a long track record in both human and animal medicine. It’s an effective, broad-spectrum antibiotic that provides the additional benefit of its anti-inflammatory properties. Veterinarians commonly use the drug to treat infection, but it was unknown whether doxycycline crosses fetal membranes and whether it’s a safe option for mares during pregnancy.

“If you’re like me, you’re frequently faced with questions about whether the drugs we prescribe are safe for use in pregnant mares,”  said reproductive specialist Igor Canisso, DVM, MSc, PhD, Dipl. ACT, ECAR (Equine Reproduction), assistant professor at the University of Illinois, Urbana-Champaign’s department of veterinary clinical medicine. “And most of the time, if you’re like me, you’re going to have a big question mark on your face because we don’t know the answer.

“There are very few drugs that have actually been studied, that we know about their safety in pregnant mares and whether they diffuse to fetal fluids and tissues. We make a lot of assumptions