Whilst the arrival of the warm spring days is bliss for many of us it can spell misery for horses which suffer from Sweet Itch. Sweet Itch is an allergic reaction caused by the saliva of biting midges; the main culprit in the UK being the Culicoides midge. Certain breeds of horse seem more prone to Sweet Itch than others; cob type ponies for example are more likely to develop the condition than thoroughbreds.
Signs and symptoms
The first sign that your horse might have Sweet Itch is usually skin trauma to the mane, neck and the base of the tail as a result of the horse rubbing against things in an attempt to relieve the itching caused by biting midges. The midges' saliva causes histamine to be released by the horse's immune system and this is what causes the itching. The more the horse rubs, the worse the damage to the skin becomes. Dryness, scurf and flaking can progress to rawness and weeping which eventually heal but leave the skin thickened and damaged. Secondary infection may occur and be stubborn to clear. Not surprisingly, affected horses often become depressed and subdued while they are suffering from Sweet Itch during the summer months and it is often impossible to continue ridden work.
Prevention, control and cure
First of all remember that Sweet Itch is an allergic reaction rather than a disease and therefore it will probably be the case that only a small number of horses in the same field will be affected. The most obvious way of preventing the problem is to stop midges from biting affected horses in the first place. Midges are determined creatures and this strategy is thus easier said than done, however there are some measures which owners can put in place to help their horses.
Midges' preferred habitat is near water, especially if it's slow flowing or stagnant. If possible, move affected horses away from the vicinity of ponds, slow streams and muddy areas. Midges are most active at dawn and dusk. If you can, stable allergic horses between about 4pm and 7am. Fine mesh screens can be fitted across stable doors and windows to prevent midges bothering stabled horses and fly paper should also be hung inside the stable to catch any interlopers. Midges find it very difficult to fly against a breeze stronger than 5 mph. Good ventilation is important during warm weather anyway and if you can generate a nice through draft by leaving windows open, this will not only keep your horse comfortably cool but will help to deter biting midges too. Failing this, a fan (positioned safely out of reach of a curious occupant) can be helpful.
When the horse is out at grass a fly blanket is useful. There are many different designs on the market and most have neck and tail covers to present a physical barrier to midges. Materials used are lightweight and cool and such rugs are very effective. It is worth noting however that netting masks which cover the horse's eyes become virtually impossible to see through when wet which can be problematic if you live in an area prone to wet summer weather (like most of the UK for example!).
Fly repellents are invaluable in the successful management of Sweet Itch although the choice can be somewhat mind-boggling. Vets recommend products containing the active ingredient, Permethrin. In addition to being a very effective fly and midge repellent, Permethrin remains on the horse's coat very well following application so continues working long after you've put it on unlike many products which seem to vanish like the morning mist the minute you walk away.
In more severe cases of Sweet Itch the horse may continue to itch despite all of the preventative measures at the owner's disposal. In such cases, the vet may recommend the administration of antihistamines or steroids.
Antihistamines are very effective in mild cases and are very safe to use but more severe cases may require the use of steroids. Prednisolone is the most commonly prescribed and works by supressing the immune response to the midge saliva, thus preventing the dramatic allergic reaction. Although extremely effective at reducing the itching and associated complications it causes, steroids do present the side effect of laminitis. Consequently, if your vet does recommend using steroid treatment, it will be at the lowest possible dose and for long term therapy of chronic, serious cases.
Another preventative option is a product called, Cavalesse. This is a natural food supplement containing the ingredient Nicotinamide, a type of vitamin B3. This works in two ways; firstly, histamine production is reduced and secondly, it increases the amount of natural fat present in the skin which increases 'barrier protection' against midge bites. Cavalesse is most effective if started in the spring a month or so before the signs of Sweet Itch begin to appear.
Sweet Itch is a chronic problem which affects different horses to varying degrees. Owners will find that experience of their own particular horse's predisposition to the condition will determine the most effective course of preventative measures and treatment.
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