SWEET ITCH

(AKA 'Summer Eczema', 'Queensland Itch', 'Summer Seasonal Recurrent Dermatitis')

This is one of the seasonal problems that besets some unfortunate horse owners at this time of the year. It affects all types of horses but is more likely to be found in the pony and cob breeds, Icelandic horses too seem particularly prone. It is also thought to be hereditary and for this reason it is unadvisable to breed from an animal with this complaint.

The cause of Sweet itch is a midge called Culicoides pulicaris.
These minute flies breed in wet, muddy areas in marshes, along the esturies of rivers and around lakes or in wet, decaying vegetable material, e.g woodlands. These midges are active, usually in swarms, principally in the early morning and late afternoon, although if it is cool and humid with no wind they may remain active throughout the day. A small proportion of horses, usually but not always, those that are outdoors all the time develop a hypersensitive reaction to a protein in the saliva of the female midge. These midges are active between the months of April to late October, but tend to be more prevelent during the months of May, June and September.

The midges that cause sweet itch usually feed along the dorsal surface of the horse (forehead, base of mane, withers, back, rump, base of tail) and it is in these areas that symptoms are first seen. These can vary from occasional rubbing of the mane and tail to complete loss of the mane and upper tail hairs. The itching can become so severe that the horse may rub itself for prolonged periods against trees and posts, often developing open sores on the head, neck, withers and dock. The skin often becomes scurfy and itchy along the whole length of their back. In time the repeated rubbing causes the characteristic thickening and ridging of the skin at the base of the mane and tail. Sometimes secondary bacterial infections can develop.

Treatment

This is very much the case of 'prevention is better than cure'. So if you know your animal is prone to this then you should aim to prevent the symptoms by careful management rather than waiting for them to develop.

These include:

move affected animals out of marshy fields and away from rivers,lakes and woods
stable then from at least 4 pm until 8 am during the summer months
use a summer sheet, preferably with complete neck and tail covers to protect the base of the mane and tail. Specially manufactured anti-midge rugs and 'pyjamas' are now available.
use a fly repellant twice daily or a long-acting fly repellant every few days
the addition of garlic to the diet can reputedly help although this has not been scientifically proven
magnesium rich mineral blocks have also been reported as causing a marked improvement in some animals

For severely affected animals the above precautions should still be undertaken, together with:

the application of soothing lotions to the skin such as benzyl benzoate
use of a coal tar soap or shampoo with careful rinsing every week or so can help to remove the scurf and scabs
where skin is very sore a corticosteroid cream may be required to help reduce inflammation and aid the healing process
long acting corticosteroid injections can sometimes be given to reduce the irritation, but this drug has many side-effects one of which is to induce laminitis in some animals, so for this reason great care should be taken and this should be discussed with your veterinary surgeon

Conclusion

The good news is that Sweet Itch only affects a small minority of animals and is not an infection that can spread from horse to horse. Unfortunately once a horse or pony has become allergic to these insects it will always remain so. Sweet Itch can be both debilitating and unsightly. It prevents the animal from being used for showing and its sores may prevent or limit its being ridden in the summer. Sweet Itch can become costly in time, effort and money and the torment and misery endured can make some ponies bad-tempered and unreliable.
Very often many of these animals are sold during the winter months when the condition is not present and the problem is passed on to another unsuspecting owner. Purchasers should always be warned about animals with this condition as they require special attention and should therefore go to experienced homes with suitable facilities, otherwise it is best to steer clear of any animal suspected of having Sweet Itch.

Other Tips

suggested
"..try tieing 'cow fly tags' on each side of the headcollar, apparently farmers use these tags to help keep the flies off their cows and they cost about £2.50 each. (The animal's body gets coated in the insecticide by the swishing of their heads and tails) Whether this really works is another matter - it's very much a case of trial and error..."

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