[Differential signs][Qld itch][Rain scald][Greasy heel][Ringworm][Lice][Ticks][Buffalo fly][Urticaria][Summer sores][Sunburn][Onchocerciasis][Mange][Miscellaneous]
Australian (Queensland) article
Updated April 2008
A good coat is a reflection of health.
In summer horses should be sleek-coated and shiny. Dappling is a sign of health, though not all horses have the genetic ability to ‘dapple up’.
In winter they grow an extra coat which is long, thick and rough-looking, but this is not a sign of ill health. It is normal for great handfuls of this winter coat to fall out in spring as the weather warms up, in fact it might fall out so rapidly that it leaves temporary bald patches.
Foals have a very woolly foal coat which they lose at about 3 months of age.
Sweating in very hot weather or as the result of exercise is normal, in fact an inability to sweat (anhydrosis) is a serious health problem. It is through the evaporation of sweat from the skin and hair coat that horses lose excess body heat. Prevention of this process, e.g. by inappropriate rugging practices, is cruel and harmful to the long-term health of the horse.
Hair loss and itching are typical of many skin diseases and can advance to abrasions, open sores, weeping, cracked, folded and thickened skin.
A dull, scurfy, scruffy or lifeless coat is usually associated with systemic ill health as well as being an indicator of skin disease.
Skin sores (e.g. galls) may be due to external trauma or rubbing from poorly fitting saddles/harness.
Hair loss and abrasions confined to around the head and ears can be due to ear mites or a recent colic attack (horse has been rolling frequently).
Generalised skin lumps or a rash might have an obvious cause like stinging nettles or insect bites, but can also be the result of systemic illness e.g. feed or medication allergy.
Localised white spots or patches of hair are often the result of past pressure sores or rubbing e.g. old saddle sores, girth galls.
Tail itching is typically associated with Qld itch (see later) but can sometimes be caused by pinworms.
Biting at the skin (self-mutilation) for no apparent reason is an uncommon but not unknown stable vice associated with too much confinement and/or lack of roughage (hay, grass) in the diet.
COMMON SKIN CONDITIONS
(Queensland)
Queensland itch
Rain scald
Greasy heel
Ringworm
Lice infestation
Tick infestation
Buffalo fly infestation
Urticaria
Summer sores
Sunburn
Onchocerciasis
Mange
Miscellaneous
The successful treatment or control of skin conditions is highly dependent on knowing the cause. For example, there is no point trying to treat Qld itch (due to an insect) with a fungicide, or ringworm (due to a fungus) with an insecticide, or lice (insects) with an antibacterial product.
Cause: insects (sandflies), therefore control by using insecticidal products.
Qld itch is an allergic response to the bite of sandflies (midges) - Culicoides spp. Only a percentage of horses are affected and some suffer far worse than others. Elsewhere in the world the condition is known as sweet itch or summer itch. In southeast Qld it mostly disappears during winter along with the sandflies that cause it, but older horses will still show evidence of it by having a sparse mane and tail and maybe thickened skin along the crest of the neck and withers, in fact bare thickened patches right along the topline in cases of long standing. In areas where sandflies persist through the winter, so will the condition.
Signs: Qld itch causes intense itchiness particularly of the crest of the neck, ears and butt of the tail, and horses will go to great lengths to scratch the irritation. Open weeping sores may develop, manes and tails become non-existent from the constant rubbing, fences and other physical structures can be damaged. It is a disfiguring condition and a misery for sufferers in its severe form. Affected horses can become difficult to ride or work due to the skin damage and constant intense irritation.
Treatment and control is aimed at keeping the midges off the horse. A great deal of time and money can be wasted on useless treatments if this simple fact is not understood.
Rain scald
Cause: bacteria (after initial damage) therefore treat with antibacterial products.
This is a common condition in areas of high summer rainfall, although it can occur due to prolonged wet weather at any time of the year. The frequent wetting slightly damages the horse’s skin allowing bacteria (Dermatophilus) to set up an infection. These bacteria are spread from horse to horse by flies or direct contact and are transmissible to and by humans.
Signs: Areas of matted, lumpy hair along the topline of the horse and down the sides, following the water run-off pattern. It usually begins on the rump. The coat feels hot and rough and it is locally painful - the horse will flinch when touched. The hair lifts off in crusty scabs which are moist underneath.
Rain scald may be confined just to the muzzle and lower face, particularly on white markings. The cause is grazing in long wet grass which has the same effect as constant rain in weakening the skin’s defences. Similarly, the lower legs can be affected.
Treatment: Antiseptic/antibacterial sprays and washes can be applied, although the condition will clear up itself once the rain stops. Protection from constant wetting is an obvious prevention – shelter shed, stable or waterproof rugging while it is actually raining. Horses with scalded backs should not be ridden.
Greasy heel
Cause: bacteria (after initial damage) therefore treat with antibacterial products.
This painful heel condition is caused by continual wetting of the lower leg and heel area, which allows Dermatophilus spp. and other bacteria to enter. It is associated with frequent hosing, or grazing or working in long wet grass, or sweat constantly running down the legs. Working on cinders or sand predisposes, the bacteria gaining entry through tiny abrasions. Unpigmented areas (white ‘socks’) are more susceptible.
Signs: crusty, greasy scabs on the lower legs, coronet region, heel area or the front of the hind cannons, particularly where there are white markings. Cracks may develop in the heels, causing lameness.
Treatment: veterinary advice should be sought if severe, use antibacterial ointments and creams for milder cases. Ancillary treatment to locally reduce pain and inflammation may be necessary. Emollients will repel moisture and assist healing. Prevention is by keeping the lower legs dry. The heels should always be dried off thoroughly after hosing or work. A final swab with methylated spirits will evaporate the last vestige of water from the skin.
Ringworm (girth itch)
Cause: fungi, therefore treat with an antifungal product (fungicide).
This is mainly a disease of young horses and is caused by several different types of microscopic fungi. The condition is highly contagious, spreading quickly where tack and grooming gear is shared, or on riders’ boots.
Signs: small, circular, scaly, hairless areas, often beginning in the girth region but can appear on the head and elsewhere. They may coalesce to form larger areas. The condition is irritable rather than itchy, so scratching and rubbing are not typical signs. Horses might seem mildly unwell in the early stages before lesions become obvious.
Treatment: Individuals are treated with antifungal washes and ointments. Fumigation of gear may be needed if the problem persists. Avoid sharing equipment between horses. In an outbreak situation, seek veterinary advice on how best to control and limit the spread.
Lice infestation
Lice are insects, therefore treat with insecticides (lousicides).
Both biting and sucking lice affect horses. Infestation is typically a winter problem, especially if horses are low in condition. Lice spread easily and rapidly from horse to horse.
Signs: Moderate itchiness. Heavy infestations of the sucking louse can cause anaemia. Lice are small, grey-blue insects that look a little like small ticks, but unlike ticks they have six legs and move actively through the hair. Eggs (nits) are greyish. If infestation is light, the lice are easiest to see under the mane, though they will rapidly move into deeper layers of the coat once disturbed.
Treatment: Lice disappear with shedding of the winter coat but heavy infestations may need repeat insecticidal treatments, also of gear and equipment. Seek veterinary advice on the best product to use. Pour-ons formulated for lice control in other animals may cause severe skin reactions in horses – check the label.
Tick infestation
Ticks are not insects. They are members of the arachnid (spider) family, therefore are controlled with tickicides .
Cattle ticks, bush ticks and scrub ticks can all get on horses and other equids.
The scrub tick is particularly a problem in bushland areas along the Great Divide and eastwards to the coast, with small pockets existing further inland. It is carried by bandicoots but readily attaches to any animal and engorges with blood before injecting a paralyzing poison and dropping off to lay eggs.
Signs: Bush and cattle ticks sometimes cause local swelling, which may be quite large, and itchiness.
Scrub ticks (paralysis tick, Ixodes) can paralyse and kill young foals. Donkeys of all ages are susceptible.
Ticks have 8 legs (insects have 6). Unengorged, they are small, flat and brown. Adult engorged ticks are dark blue-grey and the size of a pea. When they drop off they leave behind a crater-like sore in the middle of an itchy/painful lump. Treatment: In scrub tick areas, young foals should be caught and checked every second day, same as for cats and dogs. Manually remove ticks by simply gripping, preferably with tweezers, close to the mouthparts and pulling them off – it is not necessary to kill them first, nor does it matter if the mouthparts are left behind. Several cattle tickicides are registered for use in horses but seek qualified advice before using them on foals. It has been reliably reported that Swift Pour-On, though an insecticide, will prevent scrub ticks attaching to donkey foals if applied from 4 weeks of age (Wilderness Expeditions, Herberton).
Buffalo fly infestation
Buffalo flies are insects, therefore chemical control is by using insecticides, though some tickicides will also kill them.
Buffalo flies are a blood-sucking parasite of cattle in warm moist areas but they also cause intense annoyance to horses running with or near cattle. They have expanded their territory southwards in Australia and are adept at building up resistance to insecticides.
Signs: In horses, skin irritation and open sores encrusted with small dark flies with long flat wings. Buffalo flies may completely cover the backline of cattle and rise up in a cloud if disturbed. They do not otherwise leave the animal except to lay eggs in freshly deposited dung.
Treatment: An ever changing variety of sprays, pour-ons, walk-through dusts, insecticide-impregnated ear tags and insect growth regulators in the feed have been developed to control buffalo fly in cattle. Some can be used on horses, e.g. Swift, and will also control Qld itch – but always check the label.
The allergens causing urticaria or hives often cannot be pinpointed, but insect bites, feeding changes, injected or topical medications and plants like stinging nettles have all been incriminated.
Signs: Itchy small lumps or larger plaques that suddenly appear all over the body.
Treatment: Urticaria normally subsides within 8-12 hours without treatment but if the horse is obviously distressed with elevated heart and respiratory rate, then veterinary assistance should be sought immediately. Swellings in the throat region can interfere with breathing.
Summer sores
These tumour-like nodules are caused by the larvae of stomach worms (habronema) which are passed out in the dung and ingested by flies which then deposit them in wounds on the horse’s skin and in moist areas, e.g. around the eyes, sheath, vulva.
Signs: Tumour-like masses on the skin which can become very large, ulcerated and weeping due to rubbing by the horse.
Treatment: Veterinary, also to differentiate from other types of tumorous masses, e.g. sarcoids. The avermectin wormicides have markedly reduced the incidence of summer sores because they kill the stomach worm larvae both internally and in skin wounds. However, they have not totally eliminated the problem.
Unpigmented skin beneath white markings anywhere on the face and head, body or lower legs of horses can become sunburned. The condition is seriously worsened in horses that have become photosensitized from grazing certain plants of the clover family, weeds such as St John’s wort and field bindweed (convolvulus), and sometimes lantana, which very hungry horses may eat.
Signs: Affected skin becomes reddened, very sensitive, hot when touched and peels like sunburn in humans. In cases of photosensitization, the symptoms are more severe and painful, not necessarily confined to unpigmented areas and the skin might slough off. Dermatophilus bacteria are likely invaders in wet weather.
Treatment: Keep affected horses out of the sun for a few days. Seek veterinary advice if the condition is severe. Prevention is by limiting exposure to the sun during peak UV times. Apply sunscreen to unpigmented areas (the products specially formulated for animals are best). Remove photosensitizing plants or prevent horse grazing them.
This condition is considered rare now since the advent of avermectin wormers. It is an allergic response to the migration to the skin surface of larvae of the neck threadworm (Onchocerca). The adult worms live in the major neck ligaments of the horse and sometimes the tendons and ligaments of the leg.
Signs: Very itchy lumps on underside of the chest and abdomen and on the withers, neck and face. Lesions vary from pea- to marble-size. Rubbing by the horse creates weeping, scabby sores attractive to biting insects which transmit the larvae to other horses. When hair regrows on healed lesions it is often white.
Treatment: Controlled by avermectin wormers and is much less common than it was once. If it is suspected, seek veterinary verification.
Cause: mites. Mites are members of the arachnid (spider) family and are not insects, but some do respond to insecticides.
Chorioptic or leg mange is sometimes seen in winter in draught-type horses with extensive feathering and is mostly confined to the southern states (Australia). It causes intense itchiness and a moist dermatitis of the lower leg which can be confused with greasy heel. It responds to oral ivermectin.
Ear mites (Psoroptes) occasionally cause inflammation and itching inside the ears. Head shaking and hanging of one or both ears are typical signs. Treatment is with mite-specific ear drops.
Warts are small cauliflower-like lumps commonly seen on the muzzle of young horses, though they can occur elsewhere. They are contagious to other horses but not humans and usually fall off as the horse matures. If very large or so numerous that they physically cause problems, surgical removal is possible. Spread is limited by good hygiene.
Other more serious tumours of the skin, eye and genital regions include sarcoids, squamous cell carcinomas and melanomas (grey horses). Any unexplained lumps or growths that suddenly appear and/or grow rapidly require veterinary investigation.
A haematoma is a lump under the skin, often quite large, caused by external trauma, e.g. a kick. It may need draining if it has not subsided in a few days.
Capped elbow is a fluid-filled lump on the point of the elbow due to contact with the heel of the shoe when the horse lies down. Treat by using a doughnut boot around the pastern or change the shoeing.
Capped hock is a fluid-filled lump on the point of hock, usually the result of the horse rubbing or kicking his hocks against the tail gate of floats. If it happens in a stable, it is stress-related from too much confinement. Treat by keeping the horse forward of the tail gate and/or stop stabling him so intensively.
Lower leg swellings (e.g. windgalls, splints, curb, bowed tendons, bucked shins) require veterinary attention if accompanied by pain or lameness.