Written by Dr. Candice Bittner, DVM
Itching can take different forms: scratching, licking paws, head shaking, or scooting on the carpet are common itchy dog behaviors. Occasional itching can be perfectly normal but when itching becomes persistent it can affect your dog’s quality of life; including your own quality of life, too. If you have ever been kept up all night because your dog is licking its feet or thumping its tail on the floor you know what I’m talking about!
Can Dogs Have Allergies?
Why do dogs itch? Most dogs itch because of some sort of allergy. The three most common allergies are: flea allergy dermatitis, food allergies, and environmental allergies. Let’s start with the easiest dog allergy to treat.
Flea Allergy Dermatitis in Dogs
Fleas themselves aren’t a big cause of itching. I have surprised a lot of clients telling them their pet has fleas, which was news to them because their pet wasn’t itching. Some dogs are allergic to the protein in flea saliva, meaning they are allergic to being bitten and this can have lasting effects, even if they just get bitten by a one-off flea. The best way to solve itching related to fleas is staying on year-round, reliable flea, and tick prevention. But what about ticks? Learn more about tick treatments here.
Food Allergies in Dogs
Fleas themselves aren’t a big cause of itching. I have surprised a lot of clients telling them their pet has fleas, which was news to them because their pet wasn’t itching. Some dogs are allergic to the protein in flea saliva, meaning they are allergic to being bitten and this can have lasting effects, even if they just get bitten by a one-off flea. The best way to solve itching related to fleas is staying on year-round, reliable flea, and tick prevention.
What isn’t avoidable is food and environmental allergies. Food allergies start to become evident between 1-2 years of age. They can take the form of itching, vomiting or diarrhea. Typically, the allergy is to a protein in the food. The only way to diagnose a food allergy is through a diet trial with a novel protein (one your pet has never eaten before) or a prescription hydrolyzed protein diet. Hydrolyzed protein diets have the protein broken down so small that the immune system does not recognize them as allergens. Diet trials must be strict, with no outside food or snacks which can compromise the trial. Diet trials typically last 8 to 12 weeks. After this, the normal diet is reintroduced and if symptoms return, a diagnosis of food allergy is made.
It is important to note that there is no reliable blood test to diagnose food allergies and a diet trial is the only way to do this.
Environmental Allergies in Dogs
Environmental Allergies tend to pop up between seasons similar to human allergies. These include dust, pollens, certain grasses/plants, and can even include detergents and shampoos. The important thing to note about environmental allergies, is that they are seasonal and you will notice symptoms getting worse on a similar pattern year to year.
There are blood tests and skin tests to help diagnose environmental allergens but these only make sense if you are going to use that information to then have specific allergy vaccines made for your pet to help desensitize them to these allergies. This can be very beneficial but does incur a larger upfront cost. However, compared to life-long allergy treatment, the trade-off can be worth it.
Treating Multiple Types of Allergies in Dogs
An unfortunate reality is that often there are multiple allergies that happen concurrently. Your pet might have a mild food allergy which doesn’t cause too many symptoms. That is, until its ragwort season when their immune system is overwhelmed and symptoms get out of control. Avoiding one allergy, say with a strict diet, won’t provide complete relief if there is unavoidable exposure to another allergen.
Also (and this is going to come as a surprise to some people) antihistamines don’t work for pet allergies. Dogs’ allergy pathways do not work on the same histamine pathway that it does in people so dosing with Benadryl, Zyrtec, Claritin, etc. will not help them. It might just make them a little sleepy which might reduce how vigorously they are itching. Medications that do help include a short dose of steroids (not without side effects), Apoquel, and Cytopoint. The latter two work at the itch receptors in the skin only making side effects very unlikely.
In-home topical care in the form of medicated shampoos and ear cleaners (antifungal, antimicrobial ingredients) are great to help reduce the severity of the issue as soon as symptoms start. Once the skin or ears become inflamed, the normal population of yeast and bacteria in the skin can flourish and this can cause a skin infection, or in many cases, an allergic response to the larger numbers of yeast and bacteria. Decontaminating is the best way to keep symptoms minimal and to avoid secondary infection. I also recommend having an E-collar at home to use if your dog is having a flare-up before they can be seen by a veterinarian.