Animal Allergy

There are many different manifestations of allergic disease in animals, which can affect the skin, gastrointestinal and respiratory tracts. They are believed to affect up to 10-30% of dogs^1,2, 10-20% of cats^1,3 and 10-50% of horses^1,4,5 and so make up a significant proportion of the daily caseload of first-opinion practitioners.

Find out more about canine allergy

Find out more about feline allergy

Find out more about equine allergy

Find out more about food allergy

How does an allergy present?

Across different species, how allergic disease manifests itself varies quite significantly but broadly speaking clinical signs will fall into one or more of the following categories:

• Dermatological signs – presenting with pruritus, erythema and often secondary skin lesions caused by self-trauma to the skin. Horses (and occasionally other species) may also display urticarial reactions

• Respiratory signs – presenting primarily as asthma in the cat and horse and although less common, rhinitis in the dog

• Gastrointestinal signs – changes in the consistency in the stool, weight loss and increased frequency of defecation. Dogs and cats may also vomit.

Making a diagnosis of allergy

The diagnosis of allergy is reached through a process of elimination and should always begin by ruling out a number of other common potential causes. Once the diagnosis has been made, serological testing can be used to help identify the causal allergens, or in the case of food testing, aid in the selection of a dietary trial.  This information plays a key part in providing long-term support for this life-long condition. For more information on how to work up an allergy case, please log in to our dedicated Practice Portal.

The allergy threshold

Animals will frequently have more than one trigger that is responsible for causing them to become symptomatic. These include multiple different allergens, secondary infections, ectoparasite infestations and genetic defects to their skin barrier. It is often the accumulation of these individual triggers which leads to an animal displaying symptoms. This can be explained by what is known as the ‘Allergy Threshold’.

The immunological mechanisms underlying allergy are complex, but the concept of an individual animal having an allergic threshold above which clinical signs are seen, has been long established.

For a more detailed explanation and further information on the Allergy Threshold, please log in to our Practice Portal.

Identification of allergens

Serological allergy testing detects the level of IgE (and/or IgG) anitbodies present in the serum sample of an animal. Measuring these levels allows you to identify which individual allergens may be playing a part in in tipping an animal over its allergy threshold and causing it to display clinical allergy symptoms.

The identification of these allergens will allow you to take a tailored approach towards the successful long-term management of allergic disease. Not only does it provide information on which allergens to base allergen avoidance strategies on, it also provides key information for possible treatment pathways to help decrease symptoms or, just as importantly, reduce the risk of flare ups. Treatment pathways could include allergen-specific immunotherapy, medications, topical treatments or a combination thereof.

Why use serological testing to identify allergens?

Serological testing is a minimally invasive, quick and easy way to test for allergen sensitivities, without needing to refer the patient. It has the advantage of not usually requiring extensive clipping or sedation and being less influenced by existing skin pathologies or medications (see our for further information).

Recent peer-reviewed publications advocate that either intradermal or serum IgE detection can be used to select allergens for immunotherapy; with similar sensitivity and specificity demonstrated between the two testing methods.⁶ Furthermore, it has been shown that the method used makes no difference to the clinical response to allergen-specific immunotherapy; both tests are equally effective.⁷

What do I need for a serology test?

In order to complete a serology test, you will need a set amount (test dependent) of serum from the animal concerned. The animal’s blood sample should be spun down using a centrifuge, and put in a serum tube prior to sending (unless it is spun in a serum separating gel tube). The serum should be checked to ensure it is not lipaemic or haemolysed. For those without access to a centrifuge, a larger sample of whole blood can be sent; however, this does run the risk of haemolysis, which would make it unsuitable to use for testing.

For more information about our tests, on how to submit a sample, or to see our range of materials and resources designed to help you optimise sampling, please visit our Practice Portal.

Management and treatment of allergies

Management and treatment of allergies can be broadly split into two categories, both of which are equally important to consider:

• Proactive management – long-term strategies to prevent flare-ups

• Reactive management – treatment of itch and inflammation

In the early stages of the diagnosis and disease, it is important to provide both the animal and owner with short-term relief from the clinical signs. However, it’s crucial not to forget the need for a long-term strategy for this lifelong condition. Adopting a multimodal approach is the best option for achieving sustained success. For more information on allergy management, please log in to our Practice Portal.