Red looks VEERRRRYYYY pleased with his belly scratch in this video from Summer, 2008. I really never thought much about the raised, scabby spots along the midline of his belly. Figured they came from fly bites and were no big deal.
Well, thanks to Chocomare and her thread on Chronicle of the Horse (COTH) about neck thread worms, I'm thinking Red's summer itchiness may be something pretty significant that demands immediate attention. Here is the thread - get a cup of coffee or tea and settle in for over 54 pages. Did I say NECK THREAD WORMS? EEEUUUUWWWWWWWW!!! GROSS!!!! Until a couple of hours ago, I'd never heard of them. Here is what I've learned so far:
1. The scientific name for neck thread worms is Onchocerca. According to Dr. Robert Ogelsby, Onchocerca is a "parasitic filarial worm (nematode)." The adults live in the connective tissues of horses. There are four different types of onchocerca - Onchocerca Reticula prefers the suspensory tendon and flexor ligament where it can cause swelling and lameness. Onchocera Cerviculus hangs out in the ligmentun luchae. Their larvae, or microfilariae, are ingested by gnats and midges and then spread from horse to horse.
2. The hores's reactions to these nasties and their larvae can cause havoc ranging from mild irritiaton, scurf, lesions, swelling, and even unsoundness. Sometimes the microfilaria migrate into the eye of the horse. Some believe this is implicated in some forms of uveitis. While sweet itch is a distinct and separate condition, the midline dermatitus caused by neck thread worms is often misdiagnosed as sweet itch.
3. Treatment. Here things get a bit dicey. Some worming protocols state that regular worming with ivermectin will kill the larvae of neck thread worms and that there is no way to kill the adults. Blech! If you check out the COTH thread, you will read about many people finding success with a double (by weight) worming with Equimax, repeated in two weeks. The Federal Food and Drug Administration has approved the use of ivermectin and praziquantel oral paste for the treatment of dermatitis caused by neck threadworm microfilariae. However, the COTH thread's suggested dosage was established by antedotal accounts of success treatements.
So for Red? I just ordered many tubes of Equimax from Country Supply. If you are interested, here are some additional links so you can research this for yourselves: