An itchy tail does not mean pinworm

Tail-rubbing: is it worms?

The most common symptom people report to me when getting a FEC is “rubbing their tail”. However, contrary to popular belief, tail-rubbing is not a symptom of strongyle or other worm-infections, except for pinworms. If a horse is rubbing their tail in response to a pinworm infection, diagnosis of pinworms should be based on the presence of pinworm eggs on the skin around the anus – it’s a thick, yellowy-white paste that is easily seen and identified by owners (see image below). If a horse is rubbing their tail and there is no pinworm eggs, then it is highly likely that the tail-rubbing is a sign of another condition.

Two examples of pinworm puritis. This is the best diagnosis for pinworm infection. Image on the left would be considered a low-level burden, while the image on the right suggests a burden that may require treatment.

So if it’s not worms, what could it be?

Firstly, check the condition of their skin and coat. Poor skin condition may lead to itchiness, and this is the most likely reason your horse may be tail-rubbing. Adding in supplements to their diet to improve skin and coat health may be all that is needed. Protein, fats and B vitamins can make a difference. B vitamins are required for building the proteins that are required for good skin and hair growth, so it is worth having a look over their diet and making sure nothing is lacking.

If tail-rubbing is more serious, it may be a skin infection. These can range from bacterial or fungal infections through to ectoparasites. I can’t write to bacterial/fungal infections – these would need veterinary diagnosis. However initial treatment can be medicated shampoos to see if it elevates any symptoms.

The most common ectoparasite that would cause itching are horse lice. These are be identified by seeing the adult lice living on the hairs/skin. Treatment is with washing horses using an insecticide (pyrethroid) shampoo/wash. However this needs to be repeated several times as the eggs are tough and not highly susceptible to insecticides.

Less common, but more serious, is infection with horse mites. Serious mite infection will lead to mange. Mites should be treated with washes containing appropriate drugs, or oral ivermectin/moxidectin treatment. (Hence why some people with itchy horses think it was worms that caused the itchiness, as using an ivermectin dewormer decreased symptoms.)

If your horse is tail rubbing, first, check for pinworm eggs. If there are none, consider their skin condition, and if there is anything you can do to help improve it. But if your horse does have pinworms, more information on treatment and management can be found here.