Equine ringworm: signs, treatment and prevention

Equine ringworm is a highly contagious fungal infection of the skin which can spread rapidly from horse to horse, or from horse to human. Confusingly, despite the name, ringworm is not always ring-shaped and has nothing to do with worms.

There are many different types of ringworm, but the two main ones are the Trichophyton and Microsporum species. The fungus grows across the surface of the skin and around the hairs, producing a variety of changes affecting the horse’s coat and skin.

Signs of equine ringworm

Often all that is noticed in the early stages is tufts of hair that may appear raised up from the rest of the coat with a slight swelling underneath. People imagine ringworm patches to be circular, but they can be any shape. Usually, the tufts of affected hair fall out, leaving the skin underneath looking raw and sore. Classically, ringworm develops into grey, flaking areas with broken hairs, but the coat will gradually regrow over the next month.

Ringworm can appear in many different disguises. If your horse has a skin rash, sore or bald area for which there is no other obvious explanation, you need to have him checked for ringworm. If you are doubtful whether your horse has ringworm, it may be best to treat him for it anyway to avoid the risk of the infection spreading further. Ringworm is one of the few conditions where it is safe to do this.

Ringworm can appear anywhere on the body, but the most common site for it to occur is where the skin is in contact with the tack or harness, such as the saddle or girth areas. Here, the skin is rubbed and tiny abrasions develop through which the fungus invades. Young horses are said to be more at risk, probably because they have less immunity. Older horses usually have more mild signs of ringworm and recover more quickly.

A highly contagious infection

Horses do not die from ringworm so there is no crisis, but it is vital to be aware that ringworm is highly contagious. It can spread rapidly from one horse to another unless you take sensible precautions to stop the infection. The infection spreads either by direct contact, or on tack, rugs, grooming kit or buckets. Worst of all, the ringworm fungus will produce spores that can remain dormant on woodwork for over a year, contaminating stables and fencing. This is why some horses can develop ringworm when they are put in a stable that has been empty for a long time.

It is recommended that horses do not share tack, particularly girths, which, by rubbing and becoming damp and sweaty, are the ideal way for ringworm to spread.

If you suspect equine ringworm

If you suspect that your horse has ringworm, you should carry out the following control measures.

  • Keep any suspected horse separate in his own box. If an infected horse is isolated in his stable he should not spread ringworm, provided he cannot touch other horses. Crowded stableyards are always a greater risk.
  • Do not groom or clip an affected horse because of the risk of spreading spores.
  • Avoid riding an affected horse. This reduces the chance of spreading the infection and prevents the skin sores being rubbed by the tack and worsening.
  • Do not share rugs, tack or grooming kit.
  • Ask your vet to check any suspected horse.
  • Treat your horse and his stable immediately

Your vet may be able to diagnose ringworm from looking at the skin lesions, particularly if several horses are involved. Frequently, laboratory tests are needed to be certain: samples are examined under the microscope for fungal spores. Sometimes, a culture of the fungus is required, which means it can take 10 days or more before the vet has a definite answer.

Horses can catch ringworm from other animals, particularly cattle or dogs, but they can also pass it on to humans. It is one of the few conditions you can catch from your horse, so for that reason alone, the infection needs to be considered seriously.

If your horse has even a mild skin irritation and you develop a rash, you need to seek medical advice at once. Autumn, winter and early spring are the most common seasons for outbreaks of the infection.

How to treat equine ringworm

The incubation period for ringworm is between one and four weeks. If left, most cases will eventually clear up on their own, but it is best to treat it to avoid it spreading further. The aim of treatment is two fold: first, to kill the fungus and second, to destroy the infective spores. It is important to cure the infected horse, but also vital to reduce the environmental contamination.

To treat the horse, there are some effective washes which can be sprayed or sponged on to the skin. The thick, crusting lesions and the horse¨s coat usually mean that a cream is impractical. Your vet may prescribe an antifungal powder, which you need to feed to your horse. Care must be taken, however, in using this in-feed medication as it is dangerous for both pregnant women and mares. If there is any risk, you should avoid using them, as the condition can usually be cured with another medication.

It is extremely important to isolate affected horses and ponies as much as possible to limit environmental contamination. Any stables involved should be cleaned thoroughly and bedding destroyed. You should disinfect the rugs, fences and anything else a horse with ringworm has contacted.

For a disease that is non-critical, this may seem a lot of trouble, but one intensive treatment blitz can reduce the spread among horses in the area. Wooden stable walls are an ideal place to harbour ringworm spores. A variety of effective compounds are available for use on tack, rugs and grooming kit without causing damage. Environmental treatment may include five to 10 per cent bleach for concrete and creosote for wood.

If a large stableyard needs to be treated, horticultural foggers, containing anti-fungal agents, can be used. This is useful for items such as your best rug and saddle which cannot be treated with a harsh disinfectant.

Equine ringworm facts

  • Ringworm is a fungal infection of the skin.
  • If a rash or sore cannot be explained, call the vet to check for ringworm.
  • Ringworm usually appears on the tack areas, suchas where the saddle or girth rubs the skin.
  • It spreads by direct contact or by sharing grooming kit, tack, rugs or buckets.
  • Isolate any horse who is suspected of having ringworm. Crowded yards are most at risk.
  • Avoid riding an infected horse.
  • Ringworm can be passed on to the handler. If you think you have caught it, visit your doctor.
  • Treatment is a wash sprayed or sponged on to the skin, or giving an anti-fungal powder mixed into feed.

Keep up to date with the latest veterinary research and advice in Horse & Hound’s Vet Clinic, which is published in the magazine every Thursday.