Part 1: Sweet Itch
What is Sweet Itch?
This is the commonest condition affecting the mane and tail of horses and ponies. It is also known as Summer Itch, due to its seasonal occurrence which is usually from about May to October. The itch virtually disappears during the winter.
What causes it?
Sweet itch is an allergic reaction to the saliva injected when midges, sand flies and other insects bite a horse. It is caused by a hypersensitivity reaction to fly bites and only occurs in animals that are sensitive to the saliva. It can cause the affected animal to rub itself raw, but in most cases the condition is manageable.The causal agent is a small midge called Culicoides Pulicans which bites the horse on the withers and the mane area and also the tail and quarters.Does Sweet Itch occur in all types of equines?
Yes. As in all allergies some horses are more susceptible than others. Sweet itch affects about 4% of the equine population.It affects all ages and is usually seen in animals over one year old. It is commonest in non-thoroughbreds but particularly in ponies and cobs. It is very rare in thoroughbreds. The condition appears to have a hereditary factor as it is more prevalent in certain family lines. What signs does the affected animal show?
Mild to severe persistent itch of the mane and tail and also along the back towards the tail during the sweet itch season, i.e. the summer months. Some of these parts may become very raw with areas of sore, open, broken skin, which tend to bleed. The mane then becomes thickened and ridged. The hairs are shortened and standing. Loss of tail and mane hair may occur causing bald patches which can look ugly and grey due to permanent hair loss and skin damage. In some less commonly seen cases, itching along the legs and under the belly may occur in the more severe cases. Also, some of these extreme cases will rub their bellies along the ground to scratch the sore areas of their undercarriage. Some horses rub so hard that they destroy the fences in their paddocks. Others can be unsafe to ride, as they can drop to the ground suddenly in order to roll and itch themselves. But generally most cases are less severe, causing just a bald base of tail and scurfy mane. How is Sweet Itch diagnosed?
The signs are usually indicative of the condition.Diagnosis can be confirmed by a blood test but it is quite expensive and does not always give an accurate answer.What is the recommended treatment?
At present there is no cure for Sweet Itch. Once an animal develops the allergy it generally faces a ‘life-sentence’ with a persistent problem every spring, summer and autumn. The animal’s comfort and well-being is dependent on the owner’s management.It is often difficult to assess the effectiveness of a particular treatment as the incidence and severity of Sweet Itch is so highly dependent on midge numbers and apparent success may simply reflect a temporary fall in numbers due to a change in the weather. Symptoms tend to return again later when weather conditions are more midge-favourable. Many different types of treatment have been used over the years for the condition. For example products such as burned oil, sulphur, etc have been applied to the affected areas by owners who have used all alternative ‘tried and tested’ remedies with little success. Corticosteroids (anti-inflammatory injections): The veterinary treatment used may include this combination. However it is important to remember that the use of corticosteroids is not without risk of side effects and the possibility of the animal developing Laminitis, so the treatment must be fully supervised and monitored by the veterinary surgeon. Also, corticosteroids may become less effective over time, requiring ever larger and more frequent doses.Steroid tablets can be given in the horses feed, allowing the dose and its effects to be monitored carefully and altered as necessary. This is much safer than using long-acting steroid injections - and it may be the only solution for severe Sweet Itch sufferers.Benzyl benzoate: This was originally used to treat itch-mites (scabies) in humans and has been used for many years to combat Sweet Itch. It is listed as part of the contents in several proprietary formulations.Benzyl benzoate (under veterinary prescription) should be applied to the skin in the susceptible areas every day. However it is a skin irritant and should not be used on the horse if hair loss and broken skin have occurred - application should therefore start before symptoms develop in the spring. If used later its irritant properties can cause areas of skin to slough-off in the form of large flakes of dandruff.It is important to use gloves when applying insecticides, including benzyl benzoate. Particular care should be taken if they are used on ponies handled by children - they can cause eye irritation, for example if fingers transfer the chemical from the pony’s mane to the eyes.Whatever product you try, it is sensible to test it on a small area of skin first, as some horses will be sensitive to lotions applied to sore skin.Application of soothing lotions to the irritated areas is also advised in many cases. Soothing creams such as Calamine Cream or ‘Sudocrem’ can bring relief and reduce inflammation, but they will not deter further midge attack. Steroid creams can reduce inflammation.
Sweet Itch rugs, masks and hoods: There are several purpose designed rugs on the market which are popular and found to be quite effective by some users. They are designed to reduce the area available for flies to bite. They provide a physical barrier between the susceptible horse and insects. The blanket also avoids the need for use of oils, greases etc. They are made from soft, tightly-woven polyester and have elasticated edges to prevent small insects from entering underneath. They are breathable and also help to prevent UV damage to the horse’s skin. The blanket is said to have a close but comfortable fit and protects the horse from nose to tail. The hood, that attaches at the shoulders and incorporates a face mask, gives extra cover.When using fly rugs or Sweet Itch blankets it is important to avoid those made of abrasive material which could worsen the effects of rubbing. A good fit is essential but there will always be areas left exposed to the midges.Herbal Medicines: There are also numerous alternative herbal remedies also used for Sweet Itch.Oils: Some oils can be used to coat the susceptible areas of the horse. Midges dislike contact with a film of oil and they will tend to avoid it. Commonly used preparations include Medicinal Liquid Paraffin, bath oil (diluted with water). There are several oil-based proprietary formulations, for example ‘Sweet Itch Lotion’. However, oils and other repellents that are effective, usually work for a limited time. In summer a horse’s short coat-hair does not retain the active ingredient for long and it can be easily lost through sweating or rain. Re-application two or three times every day may be necessary.Greases (usually based on mineral oils) remain on the coat longer, but they are not ideal if the horse is to be ridden as they cause soiling etc. They can be effective if only a small area of the horse is to be covered. However it is impractical and often expensive to cover larger areas. Other preparations: Some preparations contain substances (e.g. eucalyptus oil, citronella oil, tea tree oil, mineral oil or chemical repellents). But they can cause an allergic skin reaction. A patch test should always be done first on the neck or flank of the horse before general use of the product. Apply to an area about 3cm across and look for any sign of swelling or heat over a 24 hour period before using more extensively.Diet: Some research has been done on the affects of adding crushed flaxseed to the diet of Sweet Itch horses and on the management of the condition. The flaxseed appears to lessen the allergic response. Some use feed additives to increase immunity to the allergies.It is important to remember that horses often lick each other in mutual grooming and any toxic substance, for example benzyl benzoate, on the skin may be ingested with harmful results to organs such as the liver. Strong chemicals in sprays or wipes are best avoided.