Allergy Testing for Pets: Blood Tests vs. Intradermal Testing
Pet allergy testing for dogs and cats can help identify causes of allergic skin disease, allowing vets and advanced practitioners to create a tailored treatment plan to target the symptoms. There are different tests available, we’ll talk you through the differences and which ones to avoid. If your pet dog or cat has symptoms of allergic skin disease and you are thinking about allergy testing then read on.
This article will discuss when allergy testing is useful for your pet and why. We’ll cover:
Does my Pet Need an Allergy Test?
Allergy testing is often suggested for dogs that have a diagnosed case of atopic dermatitis or for cats that have Feline Atopic Skin Syndrome. Your pet will generally have itchy skin disease, with or without ear disease. This may show itself as scratching, licking, rubbing, overgrooming and nibbling.
Pet allergy testing is mostly recommended when your vet or dermatologist is considering using ‘Allergen Specific Immunotherapy’ as a long-term treatment to try and manage atopic dermatitis.
This treatment involves injecting your pet, under their skin, with an immunotherapy vaccine. The vaccine has been tailor made to the results of allergy testing and the positive allergens found on testing. Allergens are the things your pet is allergic to in its environment, such as pollens and house dust mites.
What Pet Allergy Testing is Available?
There are two main types of allergy testing that your vet or dermatologist will recommend. These include:
Intradermal skin testing - considered the ‘gold-standard’ test: This requires sedation and then very small quantities of allergens are injected INTO the skin.
Blood testing - known as serological testing: This is a simple blood test, usually taken from the jugular vein.
If your pet is having an allergy test and already receiving treatment, there are drugs that must be withdrawn prior to allergy testing:
Antihistamines 14 days (Intradermal testing only)
Oral steroids ≥ 3 weeks
Injectable steroids ≥ 8 weeks
Topical steroids 2 weeks
Which Allergy Tests Would Be Less Useful?
Blood tests for FOOD ALLERGY are commercially available but have NOT been found by dermatologists to match what we find from the results of elimination diet trials. As a result, I do NOT advise blood tests for food allergy. Instead we must perform an ELIMINATION DIET TRIAL, and feed a carefully selected hypoallergenic diet for a period of time prior to challenging the diet with the old food to see if the pet reacts.
What is a Blood Test?
Blood testing for pets is known as serological testing. Typically with this type of test 7-10 ml blood is required and this is usually taken from the jugular vein in your pet’s neck. Once the blood is collected it is spun down to separate the serum from the blood cells and the serum is sent for testing. A pet allergy blood test looks for antibodies to the allergens being tested.
What are the Benefits of Blood Tests for Pets?
The pet allergy blood test procedure itself is quick, relatively painless and can be performed by any vet or nurse. One thing to consider is that your pet must not be receiving steroids and the appropriate withdrawal times are listed above.
What are the Disadvantages of Pet Blood Testing?
The antibodies that are tested do not stay in the bloodstream for a long time. If the allergen your pet is allergic to has not been encountered for some months it may not show on the test results.
For example, if your pet had a tree pollen allergy, we know that most trees pollinate in early to late spring. If the blood test is taken in the winter, many months after tree pollen season then it may fail to show up on the blood test.
Allergy testing CANNOT be used to diagnose atopic dermatitis. This MUST be done clinically by excluding parasites, secondary infections and food allergy.
This is because non-allergic, normal pets can have a positive test and up to 10% of atopic pets will have a negative test. We say these pets have ‘Atopic-like dermatitis’. They ARE allergic but we cannot say what to. These pets can be treated with other anti-allergy drugs, just not immunotherapy.
What is an Intradermal Test?
Intradermal skin testing for allergies requires sedation. During this test small quantities of allergens are injected INTO the skin, usually the lower area of the chest, and these are compared against a positive control and a negative control.
The positive control is histamine and this creates a larger, red wheal in the skin.
The negative control is a phosphate buffer solution that creates just a small, non-reactive bleb in the skin.
The allergens are compared to these two injections and a positive reaction, will generally speaking, be larger than the negative control, red and firm to the touch.
Intradermal testing is often more difficult to read in cats so we often inject a dye that fluoresces under an ultra-violet light.
What are the Benefits of Intradermal Testing?
The test is less affected by seasonal changes. For example a positive allergy result to tree pollen may still be evident out of season and in the winter.
What are the Disadvantages of Intradermal Testing?
The main disadvantage of this type of allergy testing is that it requires your pet to be sedated. The test is expensive to buy and so your vet will need a number of cases to make it financially viable, which may be why it isn’t always possible through your regular veterinarian surgery.
It also takes experience to read positive results as these can be subtle which is why it tends to be only veterinary dermatologists who perform this test. If you’re interested in intradermal testing for your pet contact us to find out more.
What are the Differences Between Blood and Intradermal Testing?
Blood and intradermal testing for allergies have both positives and negatives for pet owners to consider. Speak to your vet about what is possible and whether a referral to a dermatologist would beneficial.
Intradermal | Blood test | |
Time Test Takes | 30 minutes | < 5 minutes |
Sedation Required | Yes | No |
Affected by Timing | Less often | More often |
Expertise | High | Low |
How Much Does a Pet Allergy Test Cost?
At Advanced Veterinary Dermatology pet allergy testing costs include:
Consultation (initial referral): £300 - Does not include tests
Intradermal skin testing (including sedation): £678.50
Blood testing (Nextmune PAX test environmental): £546.58
Fixed Price allergy consultation and combined intradermal & blood testing: £1500
If you’re interested in testing your pet for an allergy, get in touch. We’ll talk you through your pet’s options and what would work best for you and for them.
Does Pet Insurance Cover Cat and Dog Allergy Testing?
Yes, the vast majority of pet insurance products will cover allergy testing.
There are some caveats to this:
Your insurance has not put an exclusion on your policy for allergic skin disease, atopic dermatitis or potentially the symptoms of allergic skin disease.
Allergic skin disease was NOT a pre-existing condition prior to taking out insurance. This can exclude cover even if your insurance company was not informed of this at the time of taking out cover. The insurers will always ask to see previous history when assessing an initial insurance claim.
You have reached the MAXIMUM amount allowed under your insurance cover.
You have a time-limited or annual policy and the condition is no longer covered because it was treated or noted in excess of 12 months prior to allergy testing.
Can I Test my Pet for Allergies at Home?
There are some allergy tests you can do at home for your pet. These include testing for a food allergy with an elimination diet trial. You can carry out a pet food intolerance test by feeding an elimination diet, making sure your pet has a specified diet.
However you won’t be able to test for Atopic dermatitis at home.There are tests available on the internet that test hair and/or saliva. However, these tests do NOT work so please don’t waste your money.
A previous study sent samples of hair and saliva to a number of these at home dog allergy test sites. They included samples from known allergic dogs with documented positive allergens, normal (non-allergy) dogs and fake fur and water. ALL of the pet allergy tests came back with positive results. These at-home allergy tests cannot be trusted! Instead speak to your vet or a veterinary dermatologist to find out what you can do.
Which Allergy Test is Best for My Pet?
In truth, BOTH blood tests and intradermal tests are often performed together as they ‘look’ at the immune system in different ways. By testing with both, vets and advanced practitioners often get a more reliable and comprehensive view of what your pet is allergic to.
However, if you wish to avoid sedation or your pet is not fit enough for sedation then the blood test would be the obvious choice (it is also a little cheaper).
If you were to pick one test based on costs, but not necessarily the cheapest test, and sedation was not an issue I might opt for the intradermal skin test as it is often termed the ‘gold-standard’ test as it may also pick up pollen out of the pollen season. Dr Simon Want BVM&S CertVD MRCVS
If you or your vet wish to talk to us about allergy testing please do contact us.
Sources and References:
Clinical signs and diagnosis of feline atopic syndrome: detailed guidelines for a correct diagnosis. Domenico Santoro, Cherie M. Pucheu-Haston, Christine Prost, Ralf S. Mueller, Hilary Jackson
Treatment of canine atopic dermatitis: 2010 clinical practice guidelines from the International Task Force on Canine Atopic Dermatitis. Thierry Olivry, Douglas J. DeBoer, Claude Favrot, Hilary A. Jackson, Ralf S. Mueller, Tim Nuttall, Pascal Prélaud, for the International Task Force on Canine Atopic Dermatitis
Written and Approved by:
Dr Simon Want BVM&S CertVD MRCVS
RCVS Advanced Practitioner in Veterinary Dermatology
Comments