What is an allergy?

An allergy is an adverse reaction to a normally harmless substance such as food or pollen (allergens). Allergens enter the body and cause the immune system to overreact and produce antibodies, which manifests as an allergic response.


Age of onset

In the dog, age of onset is almost never seen after 7 years of age, but cats do not follow this rule and allergic disease can occur at any age.

Incidence Rates

Incidence rates vary but from various clinical papers we can state that Atopic Dermatitis will affect approximately 10-20% of cats, Flea Allergy Dermatitis (FAD) up to 30% and Food Allergy 3-12%, with up to 15% undiagnosed allergy.

Incidence Rates

Atopy (environmental allergy) affects 10 – 15% of the canine population
Peak age of onset is 1 – 3 years and is unlikely to occur after 7 years of age
Adverse food reactions (food allergy) affects 5 – 10% of the canine population
Peak age of onset is > 1 year, but can commence at any time

Pre-disposed Breeds

  • West Highland White Terrier
  • Labrador
  • French Bulldog
  • Boxer
  • Basset
  • German Shepherd
  • Rhodesian Ridgeback
  • Pug
  • Bull Terrier
  • Cocker Spaniel
  • Hungarian Vizla
  • Bichon Frise

Age of onset

The peak age of onset is from 2 to 5 years for gastrointestinal and dermatological symptoms, where as respiratory symptoms tend to occur at a later stage usually 5 years or older.
Although clinical symptoms may occur in horses at any age where there is a heavy allergen load i.e pastures with a high incidence of midges, stables with high dust levels and of course the seasonal rate of pollens can vary.

Incidence Rates

It is suggested that 10-20% of horses and ponies will suffer from allergic disease at some point in their life but no accurate data is available. There is no breed or gender predilection for allergic disease in horses, however there does appear to be some inherited susceptibility for example sweet itch in Icelandic ponies.


Allergy can manifest itself in a wide range of differing clinical symptoms.

Presenting signs of canine allergy

Animal allergy - presenting signs, canine

Presenting signs of feline allergy

Allergy - presenting signs feline

Presenting signs of equine allergy

 Allergy - presenting signs - equine