Concerns about allergies seem to be on the increase and this month I have spoken to many owners worried about the possibility of their horse having a feed allergy. So, what is an allergy and can feed really be the cause? In truth, feed allergies in horses are rare and in fact, the term ‘allergy’ is one that some believe is overused even in people.
Example of lumps under the skin
Allergies are caused by the immune system overreacting to a type of protein (called an allergen) which in non-allergic horses/ people is normally harmless. This considered, true feed allergies are caused by a specific type of protein (not the amount) rather than oils or sugars as commonly thought. In fact, glucose is the only energy source that can be utilised by the brain and therefore horses could simply not survive if it were possible for them to be allergic to sugar!
If you do suspect a feed allergy, an elimination diet is by far the best action. This involves removing all hard feed from the diet for at least 4 weeks, monitoring the ‘reaction’ and then reintroducing feeds one at a time to see if the reaction returns. If it does, this would suggest that the horse is allergic to something in that feed and alternative can be tried. Skin or blood tests are available but unfortunately research to date has shown these to be unreliable.
Lumps and bumps are one of the most common reasons for suspecting feed allergies. However temperature, pollens, clipper oil, mites in forage or bedding or detergents used to clean rugs and numnahs are often the culprit and changes to feed (if any), often prove to be coincidental.
