Egg counts key to parasite control
"Talking to a client, I say: 'Your horse doesn't have any eggs right now, you don't need to deworm. And they say, 'Oh, but it's been two months, I have to deworm,'" says Natalie Carrillo, MV, Dipl. ACVIM, professor at the University of Florida College of Veterinary Medicine. "Even though you've got hard proof that their animal doesn't necessarily have to be dewormed, it's very difficult to convince any owner otherwise."
While current 8-week protocols that rotate drugs works by and large, some horses on some farms still suffer infestations, requiring the individual treatment of some animals differently from the herd as a whole.
"Today most horse owners continue to follow recommendations based on knowledge that is 30-40 years old," states Ray Kaplan, DVM, PhD, professor at the University of Georgia College of Veterinary Medicine.
"I will tell you that a majority of veterinarians in practice in the horse world are not particularly interested in parasitology, do not stay current with the literature, and don't read the articles in the journals," says Rose Nolen-Walston, DVM, Dipl. ACVIM, professor at the Cummings School of Veterinary Medicine at Tufts University. "I would have to say that most of the advice that horse owners get from their veterinarians is very out of date and not particularly evidence based. I think we have a lot of excellent evidence on what the most appropriate way to deworm horses is, but I don't think DVMs are necessarily giving that advice to their clients. They are recommending to deworm every eight weeks, and rotate dewormer each eight weeks, which is not supported by the literature at this point."