I also suspect he is doing it himself. It is so common. There are many reasons a horse will rub.
Worms. Make sure he is on a regular worming schedul rotating the wormers. There are anal worms that come out at night and cause itching. You will not see them during daylight hours.
Parasites. There are mites that are very hard to see that irritate the horse. A miticide shampoo may help.
Allergies. Many horses have allergies to many substances. A student of mine has a fabulous pony that kept rubbing ALL the hair off the dock despite treating both of the above problems. They ended up doing allergy tests and found he was VERY allergic to thirty different substances...including several grasses common in hays. He is getting allergy shots in the hope of helping this problem.
Usandpets- I have to clean his sheath I have been holding off being the weathers so cold but I will do that this weekend.
Allison- he is due to be wormed at the end of this month so I will be doing that.
Tnavas- so any anti dandruff shampoo will do? I will do all these things this weekend in hopes it'll stop! Hopefully it will because it'll be **** hard to find out who's the tail eater in the huge field if he's not rubbing it out. ;) Posted via Mobile Device
Flicka and several other horses at the barn were rubbing their tails last year too. Our vet said it was pinworms and suggested a liquid Moxidectin. I poured it down her back, and while it made a purple streak and was kinda oily, there has been no tail rubbing since.
Do you get biting insects like little gnats or mosquitoes at this time of year? If so apply vaseline to the underside of his tail and around his anus. These insects will bite under the tail and because he can't scratch there the outside of his tail suffers as he tries to relieve the itch.