Summer time with your horse

Sweet Itch is a common term for a condition caused by hypersensitivity to insect bites which produces an exaggerated response by the body leading to extreme itchiness. The response is often delayed for approximately 48 – 72 hours after initial bite.

The culprits are usually midges although other biting insects can be implicated. These include horseflies, black flies and mosquitoes. The condition is seasonal and is most common during the summer.

Clinical Signs

There are three commonly affected areas

  • Dorsal Distribution (tail to ears)
  • Ventral Midline Distribution (mid tummy)
  • A Combination of both

The signs are caused by self trauma in response to the itch and progressively become more severe.

Common signs include

  • Hair loss
  • Weeping, damaged skin
  • Scaling & crusting of skin
  • Skin thickening & development of deep folds

Affected animals will often be seen rubbing against objects and biting themselves.

Diagnosis

Made based on the typical appearance of the condition along with the intense itchiness plus taking into account the time of year.

In severe or long standing cases it may be necessary to rule out other potential causes with further tests e.g. skin scrapes, biopsy.

Predispositions

  • The condition may become worse with age.
  • There maybe a genetic predisposition and certain breeds may also be more at risk e.g. Welsh ponies, Shetland ponies.
  • The condition is most often seen in the summer months but can also be seen in autumn/spring
  • Certain areas such as fields/stables close to water (streams, ponds, lakes, and water meadow), dense vegetation (bracken etc) and muck heaps.

Treatments

  • Key is insect control to prevent the condition in the first place, but the symptoms often require treatment. 
  • Washing the affected regions daily with very diluted hibiscrub will help to reduce the itch by removing excess exudates from weeping skin. It could also help prevent secondary bacterial infection of damaged skin.
  • Topical use of steroid creams can be useful for a short time to help break the itch/scratch cycle.
  • Benzyl benzoate is a product which can be obtained on request from your Vet. It is actually a human scabies product but is traditionally used to help in the fight against sweet itch.
  • In severe cases injected or oral steroids can be used to help alleviate symptoms. This is ideally a short term treatment only, due to possible side effects of prolonged steroid use.

Preventative Measures

  • Midges are most active at dusk & dawn so avoiding turn out at these times is essential.
  • Insect repellents should be applied. There are a variety of these available commercially.
  • Covering up the horse/pony as much as possible with a decent fly rug can be extremely helpful. The Boett Blanket is a good example. (If your animal’s treatment is covered by your Insurance Policy, a letter from your Vet recommending that this type of rug is to be used as part of the treatment may help get some money towards the cost.)
  • A new product has become available called ‘Fidavet Cavalesse’ which is made up of an oral solution to be administered daily plus a topical gel to be used on the skin as and when required. Cavalesse utilizes B vitamins, containing high concentrations of nicotinamide which stabilises mast cell and inhibits histamine release.

Case study

Jenny Mobbs, our hard working receptionist has two miniature Shetlands, Pepsi & Coke. She has owned them since they were both foals and they are now 17. Pepsi has suffered badly from sweet itch for most of his life so he seemed like a good candidate to try this new treatment. This trial was started at the beginning of April 2009. As reported by Jenny “ Pepsi wears a Boett blanket in the summer but still manages to rip these as he is itching so much but not as badly as if he is not wearing one. This summer I have been giving him Cavalesse every morning and he has been so much better. My rug is in one piece, his mail and tail have improved and the skin is softening. There have been no scabs or lumps on his bum! So all in all I am very impressed with this new treatment and will restart Pepsi on it in March next year. Well done Janseen for producing it.”


equine vets