Yucky Pinworms

Yesterday evening, I took the opportunity to brush the boys off as they ate dinner. It was about 7:45 pm and just getting dark. As I usually do, I spent some time asking Guinness to lift his tail and allow me to scratch his rear. He has dark skin and all looked good back there - no sign of the runny poop that he had developed several weeks earlier. (I'd dewormed them with Zimectrin Gold 14 days ago.)

Anyway, all of a sudden he starts swishing his tail vigorously. I walked up behind him and he eagerly moved his tail to the side to show me his trouble. There was a gelatinous-looking "string" hanging down, so I hunted for something to scrape it off with. When I touched it with a stick, it tried to escape back inside! Guinness was clearly unhappy about this - so I grabbed it with my fingers! Yuck. (Yes, I do love my horse very much.)

I took the thing back over to the light and took a good look at it. It was about 3 inches long and fat on one end, but narrow on the other. Turns out that this is exactly the description of an adult horse pinworm.

I smooshed it and went back to check his rear again. This time I noticed a greyish blob of goo at about the "7:00" region of his anus. This was the same sort of unexplained "spot" that keeps showing up in that area of his body. I'd been speculating about it, but hadn't figured out what it was. Turns out that it is an egg mass. Double yuck!!

The weird thing is that the fecal sample that was taken when the vet was here for the spring exam was "negative." Since I've actually captured an adult pinworm, the vet's office has advised to retreat all the horses with an ivermectin product.

I've just read on the web that by 3 years of age, most horses have acquired an immunity to adult pinworms. Apparently, this is just another milestone that Guinness has yet to reach..