An Adventure in Allergy Testing

Itching, licking and scooting; these are just some of the things we’ve grown accustomed to with Yellow Dog. We’ve known for quite some time Yellow is an allergy sufferer, and we’ve also known it’s not food related. Yellow has atopy, one of the four main kinds of allergies found in dogs; atopy is a reaction to harmless allergens in the environment. We didn’t know exactly what those allergens were, until now.

allergic dog has belly rash

Yellow Dog developed this belly rash while we were visiting a friend’s house. Turns out, he’s allergic to cats.

Yellow’s symptoms were getting worse, so our regular vet recommended we see a specialist. We visited the Pet Emergency & Specialty Center of Marin to see a dermatologist who could properly diagnose and treat his allergies. Dr. Nicole Eckholm is one of about a dozen dermatology veterinarians in the Bay Area. She administered a skin test, testing 58 possible allergens; Yellow had positive reactions to 11 items including three types of grasses, several trees, a type of mites, and cats.

Let’s start with the testing process. Yellow Dog was such a good sport, a cooperative little guy ready to get some treatment.

dachshund jack russell mix

After the staff sedated Yellow, they got to work on the test, shaving a 4-by-6 inch patch under his arm. All of the allergens are numbered and injected into the skin along with a positive and negative control.  veterinarin injecting allergens in dog

If Yellow has a reaction, a hive or welt will appear within 15 minutes of the injection under the black dots.allergytest5

Dr. Eckholm then reads the allergy test and records the results. She feels each hive and looks at the degree of redness, which helps determine which allergens are the most significant.

allergytest3 At the end of the test, each allergen Yellow reacted to is taken from glass vials and mixed together in an allergy vaccine specifically formulated for him.


We have to be quite dedicated with Yellow’s allergy shots. He gets a shot every other day for the first 30 days, followed by a shot once a week for a year. The idea is to build up his immune system and desensitize it over time.

Administering the shots is actually quite easy but it is also important to monitor your dog after giving the injections to make sure he doesn’t have a reaction. Observe your dog for at least an hour after each shot. If your dog experiences vomiting, diarrhea, weakness, collapse, hives or facial swelling, he could be having a life-threatening reaction and you should contact your veterinarian immediately. He could have these reactions at any time, even if he’s been getting the allergy shots for months.

There is no absolute guarantee the allergy-shot regimen will work. Studies show success in about 70 percent of dogs, so this could all be for none. But we would rather take the chance to help Yellow live a more comfortable life.

“If flea and food allergies have been ruled out, I would pursue allergy testing,” Dr. Eckholm says. “Otherwise, environmental allergies will progress each year, requiring more trips to the veterinarian.”

redness in webbing of paw

When Yellow’s allergies flare up, the webbing of his paw gets red. Recently, it was extremely red when he developed a secondary infection.

Sure enough, we were frequenting the vet’s office on a regular basis and nothing seemed to work. And then, it got even worse. Yellow Dog recently developed a secondary infection, with bumps forming on his flanks and chest. At this point, he was itchy non-stop, with extreme redness in the webbing of his paws, which prompted us to seek a specialist’s help.

“As allergies progress, so do secondary infections,” Dr. Eckholm says. “This becomes much more costly than maintaining allergy shots, and makes for an uncomfortable pet.”

Once Dr. Eckholm prescribed an antibiotic, the infection dramatically cleared within two days, and Yellow’s itching was noticeably lessened. But even antibiotics should not be used as a long-term solution.

“Secondary bacterial infections can become resistant with the repeated use of antibiotics, making it more difficult, and expensive, to treat these infections when they arise,” Dr. Eckholm says.

If you suspect your dog has allergies, the first step is to visit your veterinarian for an exam to determine exactly what is causing your dog’s itching; infection, parasite, flea and food allergies are other possibilities. There are some telltale signs of atopy.

“Most dogs present with licking, biting, chewing and scratching of the paws, face and ears, which usually starts somewhere between one and three years of age, but can occur as late as six years,” Dr. Eckholm says. “The arm pits and abdomen are also common locations. Initially, itching is seasonal but in some cases, it progresses to year round.”

Most vets start with antihistamines to treat dogs with mild clinical signs. But unfortunately, allergies are progressive.

“Allergies will come back and will continue to progress as the dog gets older,” Dr. Eckholm says. “Allergy shots are the only effective method used to stop the progression of allergies.”

We did a Q-and-A with Dr. Eckholm to get some more answers on allergy testing.

Q: How do you diagnose food allergy versus atopy?

A: The only way to diagnose food allergy is by performing an elimination diet trial, which involves feeding a novel protein/carbohydrate source and/or a hydrolyzed protein for approximately eight weeks. A dietary challenge is done at the end of the elimination diet to prove or disprove food allergy. If the dog or cat does not flare up within two weeks of receiving their previous food, then food allergy is not the cause of the itching. If they do flare up within two weeks, then food allergy is the underlying cause. Food-allergic dogs are typically itchy year-round and their itching doesn’t wax and wane like pets with environmental allergies.

Q: How accurate is the allergy test?

A: Allergy testing is subjective, which is why a positive and negative control is used. I grade each reaction [on a scale of] one to four, based on how close in size it is to histamine. So if histamine is a four and eucalyptus is higher than a two, I would consider it significant. Studies have shown that 70 percent of dogs tested respond to allergy shots, which are based on the test.

Q: Why is it the allergy protocol (test, shots, etc.) only works in 70 percent of dogs?

A: We don’t know the answer to that question. It may be that the allergy test did not capture everything that dog is allergic to or it may be that pet’s specific immune system is too reactive and more difficult to desensitize over time.

Q: What other treatment is recommended if the allergy shot regimen doesn’t work?

A: If immunotherapy is not effective, there are several options for medical management of environmental allergies, which include antihistamines, steroids, Atopica and Apoquel. Unfortunately, antihistamines are only effective in 30 percent of dogs. Steroids are not recommended for long-term use due to side effects. Both Atopica and Apoquel are drugs used to suppress the immune system, which can carry side effects as well.

Q: If a dog is allergic to grass, it’s not as simple as changing your backyard grass type. What is that?

A: Pollens and mold spores can travel up to 30 miles-per-hour in the air. Therefore, it is impossible to remove them from your pet’s environment.

Q: Yellow is allergic to eucalyptus. Should I avoid products such as wipes or shampoos that contain eucalyptus?

A: There are a few specific allergens that if you can avoid, you should. So if your dog is positive for eucalyptus, then do what you can to avoid it. Another example is wool or feathers; if your dog is allergic, I would recommend they not sleep on your down comforter or wool rug.

Q: What if I’m afraid to administer shots? What other options are there?

A: Most dogs and cats get used to receiving a weekly shot. I often recommend using a positive reward, such as a high-value treat, following the shot so they associate the shot with something positive. If it is impossible to give the shots, there is a new form of immunotherapy on the market called sublingual immunotherapy. This is administered in the mouth multiple times a week.

eckholmDr. Nicole Eckholm has returned to California after working in a referral-only dermatology practice in the Washington D.C. area. She brings a unique blend of academic dermatology, through her U.C. Davis residency, and clinical private-practice dermatology, as well as several years in general practice and shelter medicine. Dr. Eckholm’s interest in dermatology grew as she found skin disease to be frustrating and hard to manage, for owners and veterinarians alike. As a specialist, she focuses on ways to improve the quality of life for pets suffering from an infectious, allergic, or autoimmune skin disease. She values the strong client-patient-veterinarian relationship that is so critical to the long-term care and management of her patients.

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