Worm count, how accurate?

[Fharoah]

We had our two yearlings a stool analysis yesterday as one has had intermittent diarrhea and the other has been really itchy. They were last wormed June 12th the itchy one with ivermectic, the intermittent diarrhea one with quest plus as I was hoping that might help. The stool sample showed nothing. The vet who did them says don't worm until November as they need some worms? I am wondering how accurate a extensive stool sample really is? Is it common to have nothing show up on a stool sample.


I am just looking for some other opinions.

[RobinL]

Yes, you can have an "empty" sample and the horse still have worms. Just means they are not shedding eggs at the time the sample was taken....

[Fharoah]

If we were to wait a while and retest how long after quest plus would give a very accurate count?

[JB]

moxidectin (Quest) is "good" for 12 weeks/3 months, so doing a FEC now, as you did, is right on target. However, as said, negative doesn't mean negative.

Ivermectin is "good" for 8 weeks, so you were 4 weeks "past due" on that (roughly) so you stood a greater chance of having something show up. But again, that darn false negative thing... ;)

If you want to work on deworming based on FEC patterns, then check again in 4-6 weeks.

Your vet is right in that it's actually beneficial for a horse to have a *light* parasite load. It stimulates the immune system and allows them to better handle the critters.

But having a negative FEC doesn't mean "don't deworm for a while, you want him to have parasites". It means (assuming it was accurate, of course) that the parasite program so far is working.