An itch to scratch

Skin allergies can be infuriating for horses, and are not always easy to avoid. Ben Curnow MRCVS explains the triggers and possible treatment options

- Ben Curnow

ALLERGIES can affect horses and ponies in many different ways. A persistent cough or wheeze when breathing could be due to asthma. Or perhaps you know a horse to be a seasonal head-shaker. But the most obvious organ of the body to be affected by allergies is the skin.

IS HE ALLERGIC?

VETS will often consider allergies if they have been called out to look at a persistently itchy (pruritic) horse. Or the horse may be suffering from hives (urticaria). Sometimes, it can be both at the same time. However, allergies are a diagnosis of exclusion. This means that all other causes of itching or hives must be ruled out prior to making a definitive diagnosis of allergic skin disease.

Questions from your vet will relate to any recent changes in the management of your horse. This could include differences in feed, bedding, washing detergent for rugs and so on. It could also relate to whether there is a seasonal link in the presentation of allergies, or if the problem has occurred before. Make sure you have this information to hand.

The skin is the largest organ of the horse’s body, and requires a thorough inspection. The vet will check the body for signs of parasites such as lice, mites or pin-worm (vet clinic, 24 August 2023). Often these are localised to certain regions of the body such as the back, limbs or under the tail, whereas allergic horses are typically itchy over their entire body.

An examination under a microscope of coat brushings and sticky-tape impressions of the skin will often form part of the diagnostic process, and occasionally the vet will prescribe an antiparasitic treatment plan to ensure that any ectoparasites (those that live external to the animal) have been ruled out.