What should you know about hives in horses?

A horse with hives may develop multiple round or irregular welts on the neck, trunk, or legs. They can appear after a new feed, medicine, insect exposure, plant contact, grooming product, or environmental change. The horse may rub or seem uncomfortable, but some hives are noticed before behaviour changes.

Swelling around the muzzle, eyes, or throat is more concerning than a few stable welts. A veterinarian can distinguish hives from other causes of lumps, skin infection, parasites, or injury.

Move the horse away from a suspected new feed, product, or pasture only if this can be done safely. Keep the horse calm, provide access to water, and photograph the skin. Record when the welts began and any recent medicines, vaccinations, feed changes, insect exposure, or exercise.

Do not give human medicines or repeat a previous veterinary prescription without speaking with the veterinarian. Avoid applying creams that could obscure the skin or cause further irritation. A veterinarian may recommend an antihistamine or another treatment after assessing the horse.

Contact an emergency veterinarian immediately if the horse has difficulty breathing, noisy breathing, collapse, weakness, severe facial swelling, or trouble swallowing. Keep people clear of a distressed horse while help is on the way.

Arrange prompt veterinary assessment if hives spread, recur, follow an injection or medicine, or occur with fever, colic, poor appetite, or marked lethargy. Do not rely on the appearance alone to judge severity.

Ask what exposures should be removed, whether the horse needs examination or observation, which treatment is appropriate for its size and health, and what changes require an emergency call.