Sweet Itch or Queensland Itch
HORSE QUESTION: My chestnut, 2 year old, Welsh/T.B. filly had this problem last year in the summer too but it is really bad this summer. I am guessing it is fly allergies and has gotton so bad she has completely itched out the top of her tail, rubbed her poor mane out until it is gone and has so many fly bites on her belly, they bleed now. Even her face and chest is being affected a bit this year. We have tried bathing her, and putting oils and lotions on her, but nothing seems to really help. Any suggestions?
ANSWER: You are describing the symptoms of Sweet Itch (Queensland Itch) to a tee. An annually recurring, seasonal, Pruritic Dermatosis of the horse, affecting the mane, tail and belly regions, caused by an ALLERGIC reaction to "Culicoides", who are most often called Midges, Sandflies, Punkies, or No-See-Ums, which are very small, blood-sucking insects.
They fly only in the warm months of the year and are most active before and during dusk, feeding often at the mane, tail and belly region. The disease is a result of a Type 1 hypersensitivity reaction (allergic reaction).
Usually only a small percentage of horses are affected. Now some horses who are predispositioned to an allergic reaction to this type of insect, may also have a reaction to the horn fly which affects the Ventral Midline. Also the common Stable Fly which may cause a reaction on the back, chest, head, neck, and legs.
Your Vet will best know which treatment to instigate. Prednisolone or in severe cases, Dexamethasone. The dose should be decreased gradually after 5 days, to the LOWEST possible dosage that controls Pruritus. Also Topical Cortisone and Antibiotics MAY be helpful if applied as a cream. Antihistamines are also effective in treating most cutaneous hypersensitivity diseases in horses.
Very important is stabling the horse inside a barn before and during dusk as these small blood sucking insects rarely enter barns. Also the use of a fan blowing air around the horse also helps as these type of insect are very poor flyers. A small amount of help can be obtained by using fly repellent each day, just before dusk.
I have heard but not researched that some horse people also believe keeping their horses in the barn during the rainy season (each and every time it rains) may help prevent this getting as bad. As continual rain causes its own set of skin problems with some horses.
I ruled out the horse being itchy and rubbing its tail out because of a heavy infestation of internal parasites (worms) because then only the tail head would be involved. I ruled out Lice or Mange because it is only happening in the summer months. I ruled out Rain Scald as the dermatitis isn't involving the entire top side of the horse and I ruled out Ringworm as the irregular patches of loss of hair and roughened skin would be entirely noticeable and not just in the tail, mane and belly region.