Ringworm is a skin infection caused by a dermatophyte (skin ‘loving’)
fungus. The fungi which cause ringworm in horses include the Microsporum
and Trichophyton species, which can infect not only horses but other animal
species, including humans. The skin lesions usually start as small
raised spots from which the hair is lost. These spread from these
spots and usually become scurfy or a thick dry crumbly scab may form.
Sometimes the lesions are sore and sometimes itchy. In many cases
there may only be a couple of lesions but if left untreated and especially
if spread by grooming, the condition can become extensive. The infection
is highly contagious and whole groups of horses can become affected in
How does it occur?
Ringworm is transmitted from horse to horse by direct contact between
horses, tack, grooming equipment, clothing, contact with infested stables
or trailers. The fungi are quite resistant to environmental factors
and can remain on fence railings and timber structures for long periods.
The most common method of spread is on tack such as bridles, boots, girths
and grooming equipment. The fungi can remain on the skin for up
to three weeks before clinical signs develop so the disease can be spread
before there are signs of infection. Very often it is a new horse
which introduces the condition to a yard. Younger animals are more
likely to be affected than older ones, although very old or debilitated
animals are also susceptible. Infection produces immunity which
is quite long-lasting.
How is it diagnosed?
The skin lesions are sometimes but not always characteristic and may look
similar to other skin conditions such as rainscald (dermatophilosis),
some cases of folliculitis. A skin scraping of skin cells, debris
and hair confirms the diagnosis. This material is examined under
a microscope and the ringworm spores, which are found in damaged hair
shafts, can be identified by their typical appearance. The fungus
can be grown in the laboratory to identify the species involved, which
sometimes helps with treatment. This is done in the same way that
bacteria are cultured in an incubator. Unlike most bacteria which
grow very rapidly, fungi take several weeks to grow and in many cases
the horse has been successfully treated before the results of the culture
How is ringworm treated?
If left untreated, some ringworm cases ‘self cure’ in 6-15
weeks. In most cases this is too long
a time to wait because of the risk of spread to other horses. Horses
with ringworm are also prohibited from competing or racing. Therefore,
apart from the need to relieve the horse’s discomfort, it makes
sense to treat cases as soon as they become apparent.
There are two main forms of treatment. Most commonly, treatment
is by washing or rinsing the affected areas with specific anti-fungal
solutions. There are several available but no one product will successfully
cure all cases and it may be necessary to try two or more different treatments
before one is successful. Most of these solutions are applied on
two or more separate occasions over a week or more. It is important
that all scabs, scurfy skin and debris are removed before treatment is
applied or the fungi will be protected from the effects of the medication.
This can be achieved by washing the area with a mild detergent and gently
using a nylon scouring pad or toothbrush to carefully lift the scabs and
debris. If the skin is raw, extensive scab removal may need to be
delayed until after the first few treatments. Rinse the skin well
and allow to dry as any water on the coat will dilute the solutions further.
At the end of a course of treatment, the lesions should have stopped
spreading, no new lesions should appear and the skin should look healthy
if bare. New hair grows quite quickly.
In severe, generalised cases or where there is an outbreak in a group
of horses, treatment with powders, (griseofulvin), given in the feed for
10-14 days can be used. These take up to six weeks to be effective
and should be used in conjunction with topical (skin surface) treatments
as described above.
Prevention and control
Where possible, new horses should be kept in isolation for 2-3 weeks and
closely monitored for signs of suspected ringworm, coughing and other
signs of infectious or contagious disease. If you suspect ringworm,
ensure that the affected horse is treated and that it has its own grooming
kit and tack, which should not be used on any other horse. Treatment
should commence immediately and the grooming kit, rugs and tack thoroughly
disinfected during and after treatment. Equipment used for treating
the affected horse should not be used on other horses and should be disinfected
or disposed of after treatment has ceased. Handlers should use gloves
when dealing with affected horses and, where possible, these should be
dealt with last.
Can I catch ringworm from my horse?
It is possible but uncommon for people to catch ringworm from horses.
The lesions are usually itchy and red patches or ‘rings’ may
form and can occur anywhere on the body. Your doctor should be consulted
to confirm the diagnosis and for a suitable treatment.
The material contained in this website is presented for information purposes
only . The material is in no way intended to replace professional veterinary
care or attention from a professional veterinary surgeon.
The advice given in any of our web pages cannot be used as the basis
for a diagnosis or choice of treatment.
Clyde Vet Group advises that you should always consult a veterinary surgeon
about any queries with animals under your care.