Shires Veterinary Practice Advice on the Itchy HorseThe itchy horse is an all too common problem encountered in the equine world. It can bevery frustrating for owners often resulting in a lot of expense and a scabby, balding, poorlooking horse.There are three main groups of conditions that cause itchy horses: 1. Parasitic. 2. Bacterial and fungal infection. 3. Allergy.Parasitic Causes of itchy Horses.Lice.Lice commonly affect horses in the winter when they have long hair or are rugged up. Therea two types of lice which can infect horses, the sucking louse Haematopinus asini (rare) andthe biting louse Damalinia equi (common). Lice can be spread from horse to horse by closecontact, sharing rugs and brushes and even on riders clothes. Horses usually appear as itchywith tatty coats and scabby bald areas where they have been rubbing.The diagnosis of lice is easy as they can just be seen with the naked eye when you knowwhat you are looking for. You can also just see louse eggs on the hair shafts. Microscopy ofhair samples can confirm the diagnosis.Once confirmed lice can be treated with powders or shampoos. I would recommend youcontact us regarding treatment as. some of the best powders are not licenced for use on theanimal. Deosect shampoo is effective as are some of the sulphur based shampoos. The besttreatment depends on your personal circumstances so please contact us for advice. Onenote of caution, citronella based powders do not kill lice they merely repel them so are bestavoided.Mites.The mite of major importance to Uk horse owners is chorioptes equi. This mite is invisible tothe naked eye and is a major problem in feathered breeds of horse. Commonly known asthe “itchy foot mange mite” it usually infests the skin and hair below the knee.The presenting signs of chorioptic mange are foot stamping, scabs on the lower leg andthick dandruff particularly round the pastern and tendon area.There are other mange mites of horses (psoroptes equi, Demodex and Sarcoptes scabiei)which are rarely recorded in the UK. As far as I know there are no products on the market licenced for the treatment ofchorioptic mange in horses. Therefore it is essential that owners consult us beforeembarking on treatment. At Shires we have had considerable success with two differenttreatment options 1. The use of injectable cattle wormers and 2. The use of a “home made”mange wash. I must reiterate that both these treatments are unlicenced so you must speakto one of our vets before considering using them.To prevent the spread of mites or re infection after treatment, all bedding should bechanged, stables disinfected or pressure cleaned and grooming kit sterilised.Bacterial and Fungal infections.Staphylococcus.There are several types of staphylococcal bacteria that can cause skin infection and itchingin horses. Most are present all the time on equine skin without causing a problem.However in the right conditions such as abrasions and prolonged periods of wet hair orsweating infection can occur.The presenting signs of staphylococcal skin infections are large weeping scabby areas whichare often painful as well as itchy. Diagnosis is from clinical signs, culture of lesion swabs andmicroscopy of impression smears (both of which we can do in our lab. At Eccleshall).Treatment consists of antibacterial “shampoos” and prolonged courses of antibiotics. Manyof the widely available antiseptic sprays will not be sufficient.Prevention involves trying to minimise the warm wet conditions this bacteria loves. Sodon’t rug up soaking wet horses for long periods of time, clip out winter coats, wash and dryafter sweaty exercise.Dermatophilous.Dermatophilous is the bacteria that causes “rain scald” and “mud fever”...yes they are thesame condition but on different areas of the horse. Rain scald presents as numerous smalloozing scabs over the back, neck, face and flanks whilst mud fever presents as similarlesions on the pasterns and lower leg. Both conditions can be itchy but are usually morepainful.Diagnosis, treatment and prevention is much the same as for staphylococcus. Get thosefeathers clipped out!! Try to keep horses clean and dry as much as possible in the winter. Ringworm.Ringworm is not caused by a worm but by a fungus (usually microsporum or trichophytontypes). The condition is highly contagious and spreads rapidly between horses. Lesions firstappear as small hairless area which rapidly grow and increase in number. They arecharacteristically scaly at first but can progress to crusty, scabby oozing patches of skin.Itching and discomfort can become an issue. One of the identifying features of ringworm isthat hair can easily be plucked from the edge of the lesion.Ringworm is usually introduced onto a yard by a new horse. It is spread by direct contactbetween horses, sharing of tack or grooming equipment and rubbing against contaminatedstables or fences. Fungal spores can survive in the environment for several months so thatfences in a field where “ringwormy” cattle or sheep were grazing can be a source ofinfection. The incubation period is up to 3 weeks so it is hard to tell which horses aredeveloping the condition.Diagnosis of ringworm is from clinical signs, microscopy of hair samples and fungal culture ofhair plucks (it can take up to three weeks for cultures to grow).Treatment is by washing with antifungal suspensions such as immaverol. Creams can be ofuse with small numbers of lesions. Unfortunately in feed griseofulvin powder is no longeravailable.Prevention is difficult and centres around limiting the spread of infection once a case hasbeen diagnosed. New horses on a yard should be kept separate for 3 weeks if possible.When moving horses to a field previously grazed by cattle or sheep, try to find out if therewere any cases of ringworm in the stock.Ringworm is a zoonotic disease ie. It can be passed from animals to humans so wear gloveswhen handling affected horses.It is important to get an accurate diagnosis and prompt treatment if ringworm is suspected.Horses with ringworm are prohibited from most equestrian competitions.Allergy.Sweetitch.Sweetitch is probably the most common and most frustrating cause of itchy horses. Truesweetitch is an allergic reaction to midge saliva after a bite. The condition is seasonal, beingworst in the summer, and presents as intense itching round the face, mane and tail headarea. Commonly, affected areas will have thickened skin, scabs and hair loss all caused bytrauma as the horse rubs. In severe cases the entire body is affected. Diagnosis is usually by clinical signs alone although a blood test is now available (see later).The most effective treatment is to prevent the horse getting bitten. This can be achieved inseveral ways. 1. Physical barriers such as summer rugs and fly masks. 2. Citronella based fly sprays. 3. Pyrethrum based pour on products. 4. Timed grazing. Turn the horse out in the middle of the day thus avoiding peak midge activity in the early morning and evening.If it is impossible to stop your horse getting bitten then anti allergy treatment is indicated.Steroids can be used with care but they do have side effects including the possible link withlaminitis (steroids are useful drugs if used appropriately, the link with laminitis is a topic ofhot debate in the veterinary world and should not prevent their use, however owners mustbe made aware of any possible risk).A new product on the market is Cavalesse. It comes in a treatment pack containing atopical gel and sachets of powder for dissolving in water. The gel can be applied direct tosweetitch lesions whilst the powder is dissolved in water and a set volume added to thefeed daily.The active ingredient in Cavalesse is Nicotinamide, a chemical found in many cells in thebody. Nicotinamide has been shown to help deactivate cells involved in the immuneresponse and thus damp down the horse’s reaction to allergens. For the best resultscavalesse should be used for at least one month before the start of the midge season.Other Allergies.At Shires we have found that many itchy horses are allergic to grass pollens, tree pollens,fungal spores and other insect bites. In such cases anti midge treatment will not cure theproblem.The most effective treatment, in our hands, for these allergic horses is to use desensitisingvaccines. This process is easy to set up but can be quite expensive. However when offsetagain all the creams and potions that clients buy from tack shops it can be quite economicalin the long run.Initially we take a blood sample from the horse and send off to the laboratory. A report isreturned telling us all the substances that the horse is allergic to. We then choose whichsubstances we want to desensitise the horse to and the laboratory manufactures a bespokevaccine. The horse is then given a small dose of vaccine every 3-4 days. Over time the dose of vaccine and the interval between injections is increased until a single monthly dose isreached. Once this maintenance level is achieved it can be continued for life.We have achieved an 80% improvement in symptoms with most horses on an allergyvaccine programme.This advice sheet is not an exhaustive work on itchy horses and some conditions may havebeen omitted. However I hope that we have given you, the horse owner, a betterunderstanding of what causes itchy horses and how important it is to obtain a correctdiagnosis.For further advice please do not hesitate to contact John, Paul or Cathy who will bedelighted to help you.
Shires Veterinary Practice Advice on the Itchy Horse
Description: Shires Veterinary Practice Advice on the Itchy Horse The itchy horse is an all too common problem encountered in the equine world. It can be
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