Summer itch. Sweet itch. Rubbing tail and mane out itch. Rubbing belly raw and leathery itch. Allergic to mosquitos. Non-responsive to antihistamines, slightly better with flaxseed. Topicals don't work. My little roan mare couldn't leave my property because she didn't have a bag over her head... last year, she was horrible. Her tail was totally gone on the tail bone, mane had about 4 inches left. Her whole belly was just like leather with open sores. She would itch constantly on anything that looked like it could be a good scratching post. This began in late 2008. She began itching around July and by September had thinned her mane out. In 2009, she got much, much worse, and last year, just awful. We tried flysprays. We tried flysheets (belly band and neck guards). Herbs. Topicals. Turnout in the least buggy times of the day. Nothing helped. Then I read a thread over on the COTH forum about Neck Threadworms, and a series of case studies of owners who had horses with similar and identical problems, who successfully treated the condition with a double-dose deworming of Ivermectin. BINGO! Lukas, one of our 3 yr olds, has also had similar itching developing, plus rainrot that randomly appears during dry weather and some weird flakey patches of skin. Neck Threadworms can be transfered to other horses by biting insects-- or I should say, the juvenile "microfiliarae" can be transfered, and these little pests are what cause the itching. The itching does not always last year-round and is more common in the spring and summer when the juveniles are hatching and causing trouble. These are microscopic--- you can't see them without a microscope. They're one or two steps up from bacteria. The adult form of this worm--- yes, it's a parasite-- is called Onchocerca Cervicalis(sp). It lives in the nuchal ligament. Yes, in the ligament. It is nowhere near the digestive system. This bad boy can grow up to 11 inches long. OH. MY. GODs. The other form, Onchocerca Regulata (or something), lives in the tendons and ligaments of the lower legs. These ones are thought by one hoofcare lady to be a cause of "contracted tendons" in young horses, and she has successfully and surprisingly quickly returned a lot of foals to "normal" by using proactive trimming and doing a double-dose deworming protocol. Within weeks. I saw the pictures. Shocking. Since the little pests are so deep in the tissue, a regular dose or under-dose (due to people incorrectly guesstimating their horse's weight, or horse spitting out dewormer, etc), is basically ineffective against this parasite... which is why even those of us who regularly and properly deworm may have not seen any positive results with our "constantly itchy" horses. A double-dose based on the horse's weight is generally not harmful to the horse (ivermectin is tested safe at up to 10 times the recommended dosage). Unfortunately, the lifespan of the adults is 7-14 YEARS... so to completely eliminate them from your horse, you would probably have to do a repeat of this double-dosing protocol every spring to kill off the juveniles and then "wait" for the adults to die. So now that we're all thoroughly itchy and really grossed out... I decided to try the double-dose protocol as recommended by the ladies on COTH. I am choosing to use Panomec (1.87% Ivermectin). Week 1: Double-dose Ivermectin Week 3: Repeat. Week 5: Repeat if horse still shows symptoms after Week 3 dose. (May have to repeat every two weeks until the horse is symptom-free. Symptoms include: - hives (big nasty hives) - increased itching - bumps "popping"/draining - new sores on belly/neck Some horses showed no symptoms after dewormings. Others symptoms immediately resolved within days. Horses who were previously asymptomatic became symptomatic. These can be alleviated with antihistamines or Benadryl. Worsening of symptoms/appearance of symptoms usually occur 2-4 days after deworming. (Even the dewormer info tag warns about this stuff happening due to the worm population dying off and exiting the body, specifically for Neck Threadworms). Wisher has been better this year due to the Flaxseed and cool, bug-free weather... but she's still rubbed a lot of her mane out and tailhead already... her belly is nasty, too. So she and Lukas were both dewormed this morning, and now we wait.