Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Hives, Urticaria


Urticaria is the presence of hives. This is a common sign of allergic disease in horses. It appears as pea-sized to quarter-sized bumps or wheals over the neck, chest, or anywhere on the body. A horse with hives may or may not be itchy (pruritic).

Hives can appear for the first time both early and late in life. Breed or gender has not been shown to increase a horse’s probability of having allergic skin disease, but familial inheritance is suspected in some cases.

In many cases, the specific cause of allergy cannot be identified. Horses with recurrent hives may have a genetic predisposition to allergy, and are reactive to many environmental allergens. In these horses, allergic skin disease is considered a lifelong problem that will need ongoing therapy for management.

Vets often choose to break the cycle of inflammation by using medications. However, not every vet takes the same approach. Some use steroids, some use antihistamines or other medications, and some try more holistic therapies. The key is that the therapy should work (bumps and itchiness should go away), and it should be coupled with management to reduce the dependency on medications. Medical therapy is aimed at using the lowest dose at the longest interval to remain symptom-free.

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 immune response is not being sufficiently dampened. The goal in the case of recurrence is to eliminate possible causes from the environment and then reintroduce them one by one until recurrence again occurs.

If there is doubt about the diagnosis, or therapy is not successful, then biopsy with histopathology or other diagnostics may be indicated. Allergy testing (either serum or skin testing) may have value in identifying the offending allergens. Skin testing is thought to be more reliable than serum testing. From the results of this testing, allergy shots (hyposensitization) to particular allergens can be attempted. This is successful in some cases.

There are some homeopathic remedies marketed for the control of allergy. Most of these products have not been studied to show their impact on management of the disease. Our best recommendation for these products it to choose ones shown to be safe. In these cases, if they do not hurt, they may help.

my vet's role


The prognosis is usually good if the problem is addressed early and the underlying cause is identified and removed. Recurrent hives can be very frustrating to treat. It can require a combination of therapies, and trial and error, to eventually reach a satisfactory outcome.

Even if the specific cause of hives is not identified, control of common triggers is important. Eliminate any unneeded topical products, medications and supplements. Launder blankets and wraps in hypoallergenic detergents.

Protect the horse from flies and insects to the extent possible. Homemade fly sprays containing a few known mild ingredients may be less allergenic. Replace wood shavings or other bedding with shredded paper.

further reading & resources

Related References:

Stepnik CT, Outerbridge CA, White SD, et al. Equine atopic skin disease & response to allergen-specific immunotherapy: a retrospective study at the University of California-Davis (1991-2008). Vet Dermatol 2012; 23(1):29-35.

O’Neil W, McKee S, Clark AF. Flaxseed (Linum usitatissimum) supplementation associated with reduced skin test lesional area in horses with Culicoides hypersensitivity. Can J Vet Res 2002;66(4): 272-77.

Author: Coauthored by Doug Thal DVM DABVP and Susan Shaffer DVM