Dog Allergy Testing: How to Pinpoint the Cause of Your Pup’s Itch

Many things can cause dog allergies, but it can be hard to pinpoint the problem. A veterinary exam along with testing can provide the answer.
By Kate Eldredge Basedow, LVT Updated August 26, 2022 Advertisement Pin FB More Tweet Email Send Text Message Print
dog outdoors scratching his skin; dog allergy testing Credit: Natee127 / Getty

Dogs can suffer from adverse reactions to a wide range of allergens—everything from the food she eats to the shampoo you use to the plants in your backyard. And because dog allergy symptoms are so similar to other health issues, it can be really difficult to pin down exactly what is causing your pup's problems.

Next time you see your dog excessively scratching an itch, it may be time to take her to the vet for allergy testing to find out the cause and get her on an allergy management regimen.

Signs and Symptoms of Allergies in Dogs

Before testing for allergies, the first step is to determine if your dog's symptoms are caused by an allergic reaction or by another health condition. Your veterinarian will help you eliminate other possible causes to get to the correct diagnosis.

Symptoms of allergies in dogs to watch out for include:

Red, irritated skin (in one part of the body or generalized)
Itchiness
Licking at paws
Recurring ear infections
Recurring paw infections
Itchy rash on hind quarters (especially in flea allergy dermatitis)
Rubbing face
Hair loss (localized or generalized)
Hives
Swelling
Sneezing
Chronic cough
Runny eyes
Diarrhea
Vomiting

Determining Which Type of Allergies Your Dog is Experiencing

There are several primary types of dog allergies, including:

Atopy: Allergen is inhaled or could be airborne and affect the skin upon contact (also known as atopic dermatitis).
Contact allergy: Allergen contacts the skin. Major causes include skin reactions to a flea collar, plants, fabrics, chemicals, creams, and many other materials. Definitely check with your vet to better understand the cause.
Insect bite: If your dog is allergic to fleas, bees, wasps, or arachnids like spiders, an allergic reaction can occur after your pup is bitten by one of these pests. Symptoms often include swelling, itchiness, skin irritation and redness, and, in severe cases, trouble breathing.
Respiratory allergies: Similar to common human seasonal allergies, respiratory allergies are caused when a dog breathes in an airborne allergen such as pollen, dust, smoke, or a household spray or cleaning agent. Common symptoms to watch for might be coughing, sneezing, wheezing, and trouble breathing (which may be serious and requires a trip to the vet).
Food allergies: Allergen is ingested and causes issues such as skin irritation, vomiting, upset stomach, and/or diarrhea.

RELATED: Allergies in Dogs: How to Help Your Pup Find Relief

Testing your dog to determine which type of allergies she's suffering from will help you treat and prevent future allergic reactions.

Allergy Testing for Dogs

Dog allergy testing partly depends on what your dog's symptoms are and what your veterinarian suspects may be causing her troubles. There are several main types of dog allergy testing, which can help you narrow down the cause.

Intradermal Testing

The gold standard of environmental allergy testing is intradermal skin testing. For this test, your dog would need to see a veterinary dermatologist and be sedated to have a large area of her coat shaved. She will then receive small injections of a number of different allergens and be monitored for reactions. The shaving is necessary to allow the dermatologist to observe the skin for any signs of an allergic response. This information is then used to create a custom allergy serum to desensitize your dog to her triggers. Unfortunately, this method does not work for food allergies.

Blood Testing

The blood test method is less invasive as it only requires a blood draw, but can also be less reliable than intradermal testing. An outside lab will test the blood for response to allergens, and the results can be used to formulate a custom allergy serum for desensitization therapy.

Elimination Diet Method

The gold standard of testing for food allergies is to do an elimination diet trial. Your vet will help you choose a diet with novel ingredients that your dog has not had before, and your dog will have to eat only that diet for eight to twelve weeks. This may sound like a long time, but it takes a while for allergens to work out of your dog's system, so it is important to stick with it and be patient.

During the trial, your dog must not eat anything off-diet, meaning no extra treats that aren't approved, and no table scraps. Any side snacking could skew the results of the trial and force you to start over. If at the end of twelve weeks your dog is symptom-free, your vet will then direct you to do a "challenge" and reintroduce the ingredient that is suspected to be the problem. If your dog's symptoms return, then you know that that ingredient was the cause of her allergies. If she is still fine, a different ingredient will be challenged until the culprit is found.

Blood and saliva tests are also marketed to confirm food allergies, but these tests are not reliable.

Flea Allergy Testing

The one allergy that is easy to diagnose is flea allergy. If your vet finds fleas or signs of fleas on your itchy dog, your dog will be started on a preventive medication that repels fleas. If your dog's symptoms go away after being treated, she likely has a flea allergy.

RELATED: How to Treat Your Dog and Home for Fleas

What’s the Best Allergy Test for Dogs?

Unfortunately, it's not that easy to say one method of allergy testing is better than others, as every dog is unique and every dog is affected by allergies differently. It is important to note that allergy testing is never 100 percent accurate.

Allergy symptoms are sometimes similar to those of some other health conditions and many dogs have multiple allergies at the same time, meaning the first type of testing you do may not give a definite answer or lead to a treatment plan that resolves your dog's symptoms.

It can be easy to get frustrated as the weeks and expenses build up, but remember that your veterinarian does not have a crystal ball. Discuss your financial limitations and your goals for your dog with your vet so he or she can recommend the course of action that is best for your dog's case.

RELATED: Everything You Need to Know About the Cost of a Vet Visit

While allergy symptoms can be managed, in most cases, allergies in dogs can't be cured and avoiding the allergen is the best course of action. With your vet's help and some patience you can successfully diagnose your dog's allergies and find an allergy treatment and management plan to keep your dog comfortable and symptom-free.