If he has been rubbing his tail, have a look under it. You may notice a sticky substance around his anus, most likely the eggs that the female has laid. This is what will be causing him to rub his behind.
I've never run across pin worms before. Where in the world did he get them? No other horses have been here, and he hasn't gone anywhere. Rowdy has been gone for 5 months, and I don't think he had them. I will check our Extension pamphlets for pasture management of parasites and see if I can figure out how to deal with them. I usually confine a new horse for a week or so after I get him, worm him, and keep the feces picked up, in case he brings any unwelcome passengers.
Feel bad my horse has had this for a couple of months and I didn't act sooner. Just thought the itch was heat or little gnat-things. I was keeping the sheath area clean, as I heard that can cause itching. I did see the pin worm on the anus, but had no idea what it was.
Stopped by the vet and ordered the wormer pyrantel. I will give it in 6 weeks. I was surprised the vet had none in stock, but they only had the kind for dogs, not horses. My horse is so much more comfortable already! I can only imagine how miserable he has been. The vet tech said the worms are species-specific; I will research that to make sure. It's amazing how a little information leads one on to find out more and more.
He's still shedding them, but they look dead. I'm still mystified where he could have picked it up. I know show stalls can harbor them, but he hasn't been anywhere near a stall. I'm wondering if some wildlife could also host the equine version. I need to research that. I have deer and auodads here. They are ruminants, not equids, but maybe??
Vet replied promptly. He said pinworms are present in lots of horses but sometimes don't cause any problems. The moral: don't assume that your horse is parasite-free even with a fecal exam. That has been my policy for many years, but it isn't fool proof.
It's been 3 weeks since the Ivermectin Gold. Nearly every day I'm seeing he is still shedding, but they appear dead. Still washing him every day. One more week till I can give him the other product. He isn't rubbing any more, thank goodness. A forum member a few years ago suggested a product called Dermafas for scarring in ears. I have been using it on his rubbed buttock areas. He is healing fine, but it's been a slow process. What a disgusting parasite!
4 weeks and time for the pyrantel. (The ivermectin gold did not clear them up.) Says it is for mature strongyles, pin worms and large round worms. I would be embarrassed for anyone to see him. He might think I did not take care of my horses.
Dosed yesterday and seeing some shed today. What a hard critter to get rid of! Will ask my vet about dosing him again in a few weeks. Maybe that is why they had to order the pyrantel for me. I'm just going by what the state vet recommended.
If anyone sees his horse scratching his rump excessively, consider pinworms and take action! Ivermectin doesn't get them.
Dosed my new horse at the same time and today I saw some shed. So he came to me with them. I now advise everyone to dose with pyrantel pamoate . The Ivermectin just doesn't get those dirty rotten pinworms. Vet gave me EXODUS MULTI-DOSE paste.
I gave the original horse another single dose. I have not seen any more in about 4 days, from either horse. I've been washing his behind every day for weeks, as per instructed. This is gross, but might be helpful to someone: as I wash his behind, I sometimes use the sprayer nozzle. The stimulation of the spray sometimes made a worm come out; she must be right at the anal opening, ready to come out and lay eggs at night. It looked exactly like the online pictures I saw. I ground her into the dirt. No wonder the poor horse was itching like mad. Asked the vet yesterday about the small rice-like pieces in the manure. He said if they are round, they are immature pinworms. If flat, they are tapes. They were round, thank goodness. Hopefully we are getting in the clear with this.
I also asked him if the worms could live outside the horse and he said no. The eggs, however, are not too bothered by cold but will die in heat or dryness.
Good luck to anyone dealing with these little monsters--the pinworms, not the horses.