>From an equine dermitology lecture:Culicoides Hypersensitivity: p 10 < 2 yrs is usually age of onset sometimes yearlings, usually some time in first two years of life. or within two years of moving into an area "dorsal feeders" - mane and tail involvement "ventral feeders" - ventral midline dermatitis this is an allergic reaction to the antigens in the culicoides saliva very pruritic - again, the lesions are caused by the horse rubbing
icelandic ponies, especially - in iceland, there are no culicoides b/c of the climate. the ponies which have developed from that area and are then taken here or to other areas where there are culicoides are exceedingly sensitive, right away. they show signs on warm days in the winter just as bad as in the middle of the summer b/c even one bite is a trigger. they are really really pruritic and have a real problem with this - probably they shoudl just live in Iceland, that's a good place for them :) dorsal lesions - head, ears, mane, withers, rump, tail; generalized. ventral midline lesions Therapy - can only manage. very frustrating, somewhat like FAD in small animals. try fly control - culicoides like to breed in stagnant water and have only a 1/4 mile flight range so if you remove all stagnant water, that can be helpful. they like to feed at dusk/dawn and through early evening hours so if youstable horse 4 pm to morning, that can cut down feeding. they do not like to fly into buildings. the best thing to do is put the horse in the middle of the barn, far from the windows. screens don't help b/c they are small. you can paint screens with insecticides, though, or buy special culicoides screens, or use various flysprays or strips on the horse. still, some animals are so sensitive they react to one lone bite. even the best control can't guarantee zero bites. medical therapy - steroids, hydroxyzine, hyposensitization as you know, if you are allergic to one thing, you have other allergies too. horse may start being allergic to culicoides - but horse is going to get onchocerca from culicoides and may be allergic to that, too. and other things. hydroxyzine is a great antihistamine for itchy horses - in human medicine they use this antihistamine for its sedative/antianxiety effects as a preop. the antianxiety effect is at a higher dose. anyway it seems this drug is great for itchy horses perhaps b/c of the antianxiety effect. hyposensitization is difficult b/c antigens are regional and when you move the horse you have to start over. one sure cure though that owners do not want to hear is find a friend who lives 1000 miles away and ship the horse there and he'll be happy for a couple of years. really that's the best way to get them to stop itching but that's not so practical. __________________________________ Judy http://icehorses.net http://clickryder.com
