You should suspect that your horse has ‘Queensland Itch’ if it develops a reoccurring, itchy skin condition every summer and if the itching occurs mainly around the butt of the tail and around the base of the mane. In bad cases the itchy areas involve the whole back area and the ears and face. Yet other horses are affected on the chest and belly (in addition to the other areas).
The usual cause of Queensland Itch is a hypersensitivity to the bites of midges (of the species Culicoides). The cause is actually an allergic reaction to chemicals in the saliva of the midge. When the horse is bitten by the midges small lumps develop in the skin and because they are intensely itchy the horse rubs itself, causing loss of hair and irritating the skin. Serum oozes from the irritated skin and scabs form. In chronic cases the skin becomes thickened and corrugated. The appearance of the skin is distinctive, but other diseases that can look similar include ringworm, tail itch, bites from stable or buffalo flies, and rain scald. Queensland itch is very common in northern Australia, roughly from Taree NSW north, although there are pockets with appropriate climatic conditions further south than this. While Queensland Itch is commonest in QLD, it is regularly seen in NSW.
‘Queensland Itch’ is mainly a summer problem although in some areas the midges are around nearly all year. It is particularly bad in areas where there is a quantity of still, stagnant water for the midges to breed in.
If you are unsure whether your horse has ‘Queensland Itch’ or some other skin condition, consult with your veterinarian for advice. Provide temporary relief of the skin irritation by applying calamine lotion or anti-inflammatory creams. Your veterinarian will usually recommend daily bathing with a pyrethroid (eg permoxin wash) for a week then once weekly once the condition is under control. In more severe cases, they will also often start a course of prednisalone (preddy granules) to reduce the initial itchiness and allow the skin to heal. Some particularly susceptible horses will need to receive this treatment every year.
Paddocked horses on large properties are difficult to treat. Many remedies have been used with variable success. Non-irritant, oil-based compounds may help because they have a sedative effect on skin and also act as a barrier to the midge. However care must be taken when using them in hot weather as the oil content can burn the horse. Residual insecticides, such as the synthetic pyrethroid-type sprays, can be used, but remember that rain will reduce the effectiveness of sprays and local treatment.
In the long term midge control measures are needed because susceptible horses are usually affected annually. Ideally, keep these horses in insect-proof stables at the times of greatest midge activity (late afternoon and early morning). A fan in the stable will help to keep the midges away (midges are not strong enough to be able to fly in the strong breeze created by the fan). A lightweight ‘cotton’ rug (these rugs are called cotton but are actually a mix of cotton and man made fibres) is a must if the horse is to be outside during the late afternoon and early morning. Be very careful if using a hood as the horse will have a much higher than normal tendency to rub the head and the hood can slip over the eyes.
If the horse is to be rehomed or sold at any time aim to relocate the horse south to an area that is not affected. Also be aware when bringing horses in from unaffected areas that they may develop the Itch. Queensland Itch is a miserable condition for horses and it is not fair to let horses suffer unnecessarily. Never just ignore the condition, always seek expert advice.
For more information please see: https://www.equiculture.net/responsiblehorsecare