I have been following a very long thread on Chronicles of the Horse Forum discussing neck threadworms as a cause of sweet itch, uveitis and fistula of the withers. The thread is called "something to kill adult Onchocerca??? " and can be found at http://www.chronicleforums.com/Forum/showthread.php?t=155469 . Recommended worming doseages and the experiences of many who have tried the protocol are contained in the thread.
A surprise to me was the discussion about threadworms causing contracted tendons in foals, and that dosing with equimax went a long way to curing that issue. See particularly post 969 (found here: http://www.chronicleforums.com/Forum/showpost.php?p=3787572&postcount=969), which includes very dramatic pictures of a foal with contracted tendons being treated and cured.
This thread, while long, is definitely worth a read.
Karen Lynd
--- On Mon, 4/27/09, sherman <sherman@xxxxxxxxxxx> wrote:
From: sherman <sherman@xxxxxxxxxxx> Subject: [RC] sweet itch treatment To: ridecamp@xxxxxxxxxxxxx Date: Monday, April 27, 2009, 10:21 PM
You've probably already ruled this out, Jill, but maybe for some others it might work. Treat neck threadworms with a dose of Ivermectin, then a second dose 2 weeks later. I'm trying to confirm the amount, I don't think it's a double dose both times, but I can't find the info right at this time. Anyone else know? Apparently the neck threadworms can be the cause of uveitis as well.
Kathy
Scientific name: Onchocerca Common name: Neck threadwormsPhysical description of parasite: Neck threadworms are long and coiled. The male of the species is shorter, being 6 to 7 cm long and the female being up to 30 cm long. Stages/lifecycles: Unlike many of the other worms that affect horses, the neck threadworm has an indirect life cycle. That means the parasite depends on another organism to get it to the horse. In the case of neck threadworms, that other species is the biting midge. The neck threadworm microfilariae live in the tissue under the horse's skin and are picked up by the midge when it feeds on the horse. The microfilariae develop to infective larvae in the midge's mouth within 25 days. The midge bites the horse again. How the parasite enters the horse's system: The horse is bitten by an infected midge. The larvae are deposited into the bite wound.
They travel to the ligaments in the neck and can also be found in the flexor tendons and suspensory ligaments, particularly of the forelegs. Effects of parasite if left untreated: Adult worms in the ligaments and tendons cause swelling and pain. There can also be bumps under the skin on ligaments and tendons caused by the hardening of dead worms. If these bumps disable the horse, surgery may be necessary. The presence of the adult worms may also cause lameness and swelling of the ligaments. The microfilariae may invade the lens of the eye, causing irritation, swelling and sometimes blindness. The microfilariae in the tissue under the skin may also cause skin irritation.
