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“Pruritus” from Equine Mites a sensation that causes the desire or reflex to scratch by Tabitha Jones

An itchy horse that rubs his mane and tail or bites the underbelly may just have mites! Mange is an intensely itchy skin disease caused by tiny insects called mites. Most mites you cannot see with your naked eye, hence identification is usually delayed and the horse will exhibit itchy symptoms for no apparent reason. Mites live on the surface of the skin or in tunnels a few millimeters beneath the skin. Females deposit eggs in burrows or beneath scabs. Eggs hatch in about four days. Mites reach maturity soon thereafter and live only one to two weeks. The whole cycle takes only 15 to 20 days. For horses suffering from chronic mange, the life cycle of the mites just keeps repeating, infecting the horse on a continuous basis. Unless treatment is received, the horse will have no relief. There are several species of mites that affect horses. A number of possible causes must be considered when confronted with an itchy horse, including fungi, insect bites, irritating plants, mechanical abrasion, lice and mites. When should I be concerned that my horse may have mites?  Psoroptic mites- Look for mane and tail rubbing, crusty skin, occasional small red lumps, inflammation, thinning of hair in these areas. Horses may present with head shaking and a drooping ear.  Chorioptic mites - Look for epidermal debris between the hairs at the skin surface below hocks and knees –symptoms include leg stomping, chewing and rubbing lower legs on anything in sight. Severe cases result in hard crusts that split and bleed.  Sarcoptes mites – Small red lumps appear on the horses skin especially near the head, ears, neck, chest, flank and abdomen – secondary infection likely causing crusts, weeping serum, hair loss and thickening of skin.

The Diagnosis Diagnosis should always be performed by a qualified veterinarian. In most cases, scrapings are taken from the edge of the lesion where there are thick crusty flakes. Skin scrapings should be placed in sealed containers and promptly taken or sent to a laboratory for a thorough examination. Another effective method of collecting mites from the skin surface and hair is by using a vacuum cleaner fitted with an in-line filter. The material collected along with the filter is then examined as a skin scraping would be.

Psoroptic mites also called tail mites, produce lumps and patches of hair loss over in the mane and tail. Psoroptes are pearly white in colour. Horses may present with head shaking and a drooping ear. The Psoroptes mite prefers ears and areas of thick hair, but untreated infections will spread over the entire body surface of the animal. They live in colonies on the surface of the skin and spread very quickly. These oval shaped non burrowing bloodsuckers of 0.6ml long with 8 legs live on the surface of the skin, causing a pruritic otitis externa in horses. Bites of these lymph sucking mites cause inflammatory lesions that ooze fluid which dries to form crusts. The infection is known as psoroptic mange. The bare scabby areas produced are unsuitable for the mites, which migrate to surrounding healthy skin, potentially spreading tissue damage over the entire body Psoroptes mites can survive off the host for 2 to 3 weeks.

Chorioptic mites cause leg mange. They are commonly found below the hocks and knees and especially affect breeds with heavy leg hair known as feather. Severe cases will affect the udder/scrotum, tail head, and perineum These mites live on the surface of the skin and chew on the skin rather than burrow. Easily identified by the scabs, crusts and patches of hair loss. The affected horses stamp the ground and bite their legs in an attempt to get some relief. Since this mite can survive the cool of winter it is vital that the stables and paddocks be treated for this mite as well as the infected animals. Chorioptes mites are able to feed and survive on hostproduced epidermal debris at the skin surface, without necessarily attacking the living parts of the host’s skin. Chorioptes bovis occurs widely on cattle, goats, sheep and horses.

Sarcoptes are round, fat mites with short legs who copulate on the surface of the skin after which the female burrows under the skin and lays her eggs in the tunnel she creates. These mites are often found on the head, ears, neck, chest, flank and abdomen, lower legs and tail but they can eventually cover the entire horse. Because of their activities in the epidermal layers of the skin, mange caused by these mites is generally more severe than that caused by mites dwelling above the surface of the skin. As the horse rubs, paws and bites at the skin to relieve the irritation, the resulting trauma produces further skin injury with crusts, weeping serum, loss of hair and thickening of the skin. Secondary bacterial infection is common. This type of mite is highly contagious and can spread not only by direct contact but also by sharing tack and grooming tools.

Treatment For psoroptes and sarcoptes mites the usual recommended dose administered by a veterinarian surgeon is 200 Âľg/kg bodyweight of injectable Ivermectin to repeat the treatment at 14-day intervals for a total of three doses for known infested animals, with two treatments advisable for in-contact horses. Always consult your veterinary surgeon prior to administering any potentially dangerous medication. Overdosing could be fatal.

Pour-on preparations of ivermectin licensed for livestock are known to be an irritant to the skin of horses and should not be used. However some success has been reported with the use of injectable formulations of ivermectin applied topically to affected areas. Localised treatment may however run the risk of failing to treat mites elsewhere on the body. For Chorioptic mites treatment success clipping is advised before applying an anti-parasitic agent. Ivermectin reduces mite numbers, but may not be 100% effective. Remember to treat the entire body as the mites can migrate to areas such as the neck, trunk and face. It is important to also treat in-contact horses and to decontaminate the environment. Selenium sulphide based shampoo has recently been shown to be a safe and effective treatment for equine chorioptic mange (Curtis 1999). In an open-pilot trial selenium sulphide shampoo was used to treat seven horses, two of which were also subjected to clipping of the hair coat from the distal limbs. The horses were treated with whole body shampoos on three occasions at five day intervals and no live mites were found in skin scrapings from any of the horses at follow up examinations. No adverse effects were observed in the treated horses or in the stable staff applying the treatment. Selenium sulphide based shampoo is available through some pharmacies. Some veterinarians treat sarcoptic and psoroptic mites with organophosphate insecticides applied to the horse's skin every 12 to 14 days. Topical treatments of organophosphate insecticides are generally effective against chorioptic mites. The skin should be completely saturated and washed and scabs should be dislodged with a stiff brush. Use of antibacterial medications can be used to treat secondary infections.

Natural alternative Treatments Yellow milling sulphur mixed with an oil based solution either homemade or commercially bought such as Shapley’s M-T-G works to suffocate the mite in the oil whilst the sulphur acts as a natural insecticide. Sulphur is non-toxic to mammals, but it may irritate eyes and skin. Sulphur may change the color of some jewelry. Apply to affected areas at least every 3 days for 21 days. Find online at in Australia. Lime

sulphur is made by boiling lime and sulphur together. This mixture is used as a dormant spray for mites. Diluted solutions of lime sulphur (1:32) can be used as a dip for pets to help control ringworm (fungus), mange and other dermatoses and parasites. (Undiluted lime sulphur is corrosive to the skin and can cause serious injury). Neem is

a botanical pesticide derived from the seeds of the neem tree, a native of India. The neem tree supplies at least two compounds, azadirachtin and salannin, that have insecticidal activity and other unknown compounds with fungicidal activity. Neem has been used for more than 4,000 years in India and Africa for medicinal as well as pest control purposes. Find online at in Australia. Neem oil can be applied at a ratio of 50/50 neem to a base oil – any safe carrier such as olive, coconut or mineral oil can be used. Apply at dusk to avoid sunburn or over heating from the oil. Use at every 3 days for 21 days. Do not use on pregnant mares. Pyrethrum is non-toxic to most mammals, making it among the safest insecticides in use. There has been reported good success of the use of a dry powder substance called Diatomaceous Earth or DE. If you go to the website you can read about it and they also sell it.

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Equine Mites  

An indepth article on equine mites in mane tail and feather. Everything you need to know and how to treat successfully. Find out why your...

Equine Mites  

An indepth article on equine mites in mane tail and feather. Everything you need to know and how to treat successfully. Find out why your...