I recently read a quote that went something like ‘Land of hill and heather, land of awful weather, land where the midges gather, Scotland the brave.’ The quote certainly made me think that there are definitely times you have to be ‘brave’ to risk venturing out into the woods, most especially early in morning or on a mild summery evening unless you are armed with barrier creams, repellents and nets. With midge season now firmly upon us, I thought this week and next we would look at a problem in horses that is predominately caused by these wee pests called sweet itch.
More correctly known as Cullicoides (the proper name for midges) hypersensitivity, sweet itch can be the bane of any horse and their owner’s life. The horse or pony reacts intensely to the bite of midges or flies with extreme itching and skin irritation causing them to often frantically rub or bite at the affected areas. If you are one of the unfortunate people, like me, who have more sensitive skin and therefore react and suffer after any mosquito bites on holiday, you will be able to sympathise and understand how one horse in the field seems barely bothered by flying insects whereas another can react so intensely. Although any kind of equine can be affected it is most common in ponies and donkeys and appears to be more prevalent in those animals with darker coloured coats. It is also believed that it may be genetically passed on through breeding. The condition is nearly always seasonal being worst over the summer months, settling over the winter but then generally recurring again the next year. Some people also find it has a tendency to get worse year on year.
The classical areas you would expect to see skin damage with sweet itch are the base of the mane, over the rump and the head of the tail. As well as broken hairs, bald patches and thickened skin you may see crusting and scabs. In more extreme cases these areas can get infected and oozy and be covered with abrasions from self trauma. Other areas of the horse can also be affected and animals can actually lose weight and become more nervous due to the intensity by which it distracts and obsesses them. Usually diagnosis can be made based on the clinical signs (looking at the type and distribution of the lesions), but your vet will probably want to take a full history and perform a complete physical examination to rule out any other cause. If there is any doubt, there are certain blood tests that can help aid diagnosis or something called intradermal skin testing may be done. What this involves is clipping a small patch of hair off and either applying onto the skin or injecting into it, a substance containing products that should cause a reaction in sweet itch sufferers. In more complicated cases a skin biopsy can be taken but for confirming sweet itch this is rarely necessary.
Next week we will finish looking at the topic of sweet itch importantly learning what can be done to help manage and treat the condition, and how control and prevention at the right time are essential to improving the affected animals’ quality of life.