What you see. The starting point for addressing any equine health related issue is your observation.


Multiple Small Bumps on Skin, Hives


The most common reason that horses develop many small bumps on their skin is allergic hives (urticaria), but there are other causes that should also be considered. If the bumps appeared very suddenly and are distributed all over the body, it is likely true hives. The "trigger" allergen may have been inhaled, ingested or might have contacted the skin directly. In our area, the most common summertime trigger is insect hypersensitivity.

Recurrent hives (urticaria) come from continued hypersensitivity to an allergen in the environment. Recurrence after treatment indicates that the offending allergen is still present and that the horse is allergic to it.

There may be other reasons for the development of widespread skin bumps but these are usually more slowly developing, and fewer in number.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If this problem seems severe and has come on suddenly.
    • If the horse seems particularly distressed by the problem.
    • If the problem seems severe, or involves a large area.
  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If the problem seems very mild and limited to a small area.
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.

your role


What To Do

If you feel that this is an allergic response, then consider any recent changes you have made and try to take away that stimulus. For instance, if you used a new fly spray, then maybe bathe the horse and don't use the fly spray again. If you just introduced a new feed or bedding, then discontinue using it until the situation can be evaluated by your vet. Take a photo of the bumps and share with your vet. Look and feel all over the body and determine the rough distribution of the bumps and describe that to your vet.

If you suspect hives, carefully examine your horse's environment and be prepared to help your vet to try to identify possible causes. Talk to your vet about any management changes you have made. Take Only use mild topical fly sprays to reduce insect irritation.

If you have medications like steroids or antihistamines, then let your vet know this. They may suggest you treat the horse prior to their examination. You should use these medications only under the guidance of your vet.

What Not To Do

Do not use high doses of (or repeated doses of) steroids or antihistamines without first talking to your vet. Long term or excessive steroid use may cause health problems, especially laminitis.

your vet's role

Your vet first evaluates general health and the skin bumps. They consider environment and management historyto determine whether this is really hives or something else. The diagnosis will determine their choice of appropriate treatment. I often treat hives initially with a small dose of steroids, but I look carefully at underlying reason and try to eliminate those too. Otherwise the hives will likely recur as soon as the medication wears off.

Identifying the cause of hives is not always easy, and is often based on a slow process of elimination, reintroduction and assessment. The goal is to definitively identify the offending agent and remove it. Sometimes that is not possible. In the meantime steroids or antihistamines can be used for symptomatic treatment.
Questions Your Vet Might Ask:
  • Are flies bothering the horse?
  • When did you first notice this?
  • How many bumps are there?
  • Where do the lumps or bumps seem to be located?
  • What is the horse's age, sex, breed and history?
  • Has anything changed in your horse's environment such as bedding, feed, topicals, fly sprays?
  • Has the horse worn a new blanket or saddle pad?
  • How old is the horse?
  • Did you wash your horse's blanket with a new detergent?

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
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Treatments Your Vet May Recommend

A way to resolve the condition or diagnosis. Resolving the underlying cause or treating the signs of disease (symptomatic treatment)

Very Common
more treatments

further reading & resources

Author: Doug Thal DVM Dipl. ABVP