Ringworm is the most common fungal skin infection in horses. Vet Poppy Mitchell explains how to recognise and deal with the problem swiftly to prevent it spreading
Finding a single tuft of raised hairs sticking up from your horse’s coat may not cause much concern at first – maybe he’s caught himself in the field or has been bitten by a fly? But when several more tufts appear and there’s no obvious cause, what could be responsible and should you be worried?
One of the possible causes is ringworm, a highly contagious fungal skin disease. A fungus is a type of organism that breaks down and feeds on the substance it lives on, and produces reproductive spores that enable it to spread easily. The fungus responsible for most cases of equine ringworm is Trichophyton equinum, which is particularly adapted to horses. Rapid diagnosis and treatment are essential in order to prevent further spread, which can occur very quickly.
What to look for
The first signs of ringworm become evident from six days to six weeks after contact with the infection – this is called the incubation period. The number of ringworm patches vary from one to many, depending on the horse, and are often seen on areas subject to local trauma, such as rubs from tack, rugs and riders’ boots.
Usually, circular tufts of hair 1–2cm in diameter are seen standing up against the lie of the horse’s coat, sometimes surrounded by a raised ring. If you look closely, you’ll often see a cigarette ash-like deposit between the hairs. After approximately six days, the hairs can be easily plucked away, leaving silvery, scaly skin beneath. Later, as the healing process is underway, new hairs grow within the centre of the hairless circles, giving the classic ringworm appearance.
Less commonly, a horse with ringworm may present with generally scaly skin and irregular hairless patches. It is uncommon for horses to be severely itchy or in pain when they have a simple ringworm infection, but mild irritation or reddening around the scaly patch may be seen.
If you spot changes to your horse’s coat and you know that he’s been in direct or indirect contact with ringworm infection within the previous six weeks, then it’s likely that this is the problem.
You should also be suspicious if your horse…
- has recently shared transport, stabling or tack with another horse
- has been to a show or event and touched other horses
- is young or elderly
- is immunosuppressed due to medical treatment or an underlying condition such as PPID (Cushing’s disease)
To find out more about how ringworm is diagnosed and treated, get your copy of February Horse&Rider here, on sale 15 December.