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Does My Pet Have Allergies? Part 1: The Different Types of Allergies and What They Look Like

Updated: Nov 4, 2022

Maybe you’ve been back to the vet so many times you’re on a first-name basis with the staff, or maybe it’s your first time since your pet started showing some funky symptoms. Either way, hearing the words “your pet might have allergies” can instill a sense of dread in even the most experienced pet parents.

Allergies in pets can be complicated, especially because they can’t talk to us! In fact, just identifying the specific allergen your pet is reacting to can be challenging and costly. True allergies are a life-long challenge with symptoms that may wax and wane over the seasons (just like in humans—hay fever, anyone?). But wait, you may be thinking: what’s a “true” allergy? Does that mean there are “fake” allergies? Well, they’re not called that, but yes! Some allergens can be avoided, and some sensitivities can mimic allergies—in these cases, there may be a light at the end of your allergy-symptom tunnel!

With that said, hold on to your allergy medication: we’re doing a deep dive into what your pet’s symptoms might mean!


Does My Dog Have Allergies? What Different Types of Allergies Look Like in Dogs

What Are Allergies?

Allergies, also known as hypersensitivity, are immune system reactions. This is when the body recognizes a foreign or harmful substance and launches a full-scale attack in the form of histamines and other combative chemicals (1). These reactions can vary in intensity, from localized itching to full anaphylaxis. The less dramatic allergic reactions—like chronic skin conditions—are usually the most common allergic reaction, and often the symptom pet-parents are most interested in curing.

What To Look Out For In Different Types of Allergies:

Life would be so much simpler if there was one single allergy symptom that we could point to and go, “yep, that’s definitely an allergy!” Unfortunately, life (and medicine) is never that easy. Allergens can be inhaled or—more commonly with pets—absorbed through the skin or gastrointestinal tract. Either way, symptoms manifest in a few different ways. If you’re beginning to see suspicious signs, you can begin to narrow down the possibilities into a few broad allergy categories.

1. Food Allergies

Some pet food companies make it seem like food allergies are one of the most common ailments, but in reality, it’s actually the least common! Less than 1% of dogs and cats are diagnosed with true food allergies when experiencing any disease, and less than 5% of dogs and cats are diagnosed when they have any kind of skin disease (7,22).

On the other hand, there are intolerances, which, annoyingly, tend to look very similar to allergies—this is what we meant by the previously mentioned “fake” allergies. If you know someone with celiac disease, they’ll be the first to tell you that it’s not just a “gluten intolerance”—the difference between allergies and intolerances is really important! The main difference is that reactions to intolerances are not due to an immune system response like allergies (11), instead they are simply a chemical reaction to certain foods. Unlike allergies, food intolerances tend to show up relatively quickly after trying a new food, and will never result in anaphylaxis.

Where Symptoms Can Appear:
  • Face: They may be rubbing their face excessively; look for reddened skin and hair loss around the eyes, chin, and muzzle.

  • Ears: Persistent ear infections are a fairly reliable sign of food allergies; look for discharge or a strong smell, and pay attention to excessive itching of the ears. About 25% of dogs with food allergies will only present symptoms through ear infections.

  • Skin/Coat: Itchy, swollen skin, which may have hives; look for non-seasonal itchy skin to differentiate between food allergies and environmental allergies. This will often be accompanied by bacterial infections, hot spots, areas of hair loss, and various skin lesions. The skin may feel dry, flaky, crusty, or greasy with a bad odour.

  • Paws: The paws may give off a strong odour and be red and swollen from licking and chewing.

  • Other: Other signs may include vomiting and diarrhea, which may occur alongside skin reactions (7,22). These symptoms only show up in about 20% of food allergy cases but are often present with food intolerances (7,22,13).

Some Points to Consider With Food Allergies:
  1. They tend to develop over a prolonged exposure time (e.g. a pet eating a chicken-based food for years may slowly become allergic to chicken).

  2. Food allergies can start kicking in at any time, but they can be more likely to show up when other skin-related diseases develop (1,2,7,22).

  3. Some breeds are more at risk for developing food allergies.

    1. Dog breeds include Labrador Retrievers, German Shepherds, Cocker Spaniels and West Highland White Terriers (7,12).

    2. Cat breeds include Siamese, Burmese and Persian breeds (7).

  4. Dogs’ most common allergies are to beef, dairy, chicken, chicken eggs, wheat, lamb, and soy, and they tend to get itchy all over (7,22).

  5. Cats’ most common allergies are to beef, chicken, and fish and they tend to be itchier around the head and neck (7,22).

  6. 20–30% of dogs and cats with other allergic diseases may also have food intolerances or allergies, so if you know about one allergy, be on the lookout for more (7,22).

If you suspect your pet has a food allergy or intolerance, then something called an “elimination diet” may be your only hope; we’ll go over elimination diets in Part 2 of our allergy series.

Types of Allergies in Pets

2. Environmental Allergies

Also known as atopy or atopic dermatitis, this is the more traditional type of allergy that we think of in people—pollens, molds, fungi, dust mites, grasses, weeds, etc. While these are often considered “inhalant” allergies because the allergen is generally airborne, inhalation isn’t as common in our pets as in people (4,11,15). Our pets mostly experience allergens coming into contact with their skin and getting absorbed through a compromised layer of skin, such as a rash (6,15). Once these allergens are introduced to the immune system, it recognizes them as foreign and begins an allergic response (5,6,15). This type of allergy presents very similarly to a food allergy, but it’s important to distinguish between them to get on the right track for diagnosis and treatment. Unfortunately, the most reliable method of determining if your pet has environmental allergies is eliminating all other possible issues that could be causing similar symptoms.

Where Symptoms Can Appear:
  • Face: Their eyes might be watery and surrounded by red skin; they may have rubbed off some fur from itching against the carpet and furniture. Be on the lookout for coughing and runny noses.

  • Ears: Ear infections can be chronic issues with environmental allergies too! Make sure you’re checking your pet’s ears regularly so you’ll know when something looks or smells strange—look for excessive head shaking, rubbing, hair loss on the ears, and discharge with a nasty smell.

  • Skin/Coat: You may notice your pet is obsessed with itching and scratching, especially around their armpits, groin, and ankles. They may get hot spots, have scabs, scaly or thickened and pigmented skin, and be more prone to bacterial infections. Dandruff may be a predominant issue.

  • Paws: They might be unable to stop themselves from licking and chewing their paws raw. There may be a strong and unpleasant smell, and the paws themselves may be swollen and discoloured where they’ve been licking.

  • Other: Issues with hairballs (did you know cat’s should only be coughing up hairballs less than once a month?) and anal gland issues can all be indicators of environmental allergies.

Some Key Points on Environmental (Atopy) Allergies:
  1. Atopic symptoms commonly first appear in dogs between 1–3 years old and 1–5 years old in cats (7).

  2. There aren’t any peer-reviewed statistics for how frequent atopy in pets is, but it’s still more common than food allergies (5,6,7).

  3. Pets with atopy also have an increased risk of development of food allergies (5,6,7).

  4. Atopy is a condition that can only be managed and not cured, so treatment and prevention will be integral for your pet’s entire life (1,3,4,5,6).

  5. Immunotherapy treatment for atopy works best if started early, so it’s better to get a diagnosis sooner rather than later (1,4).

3. Food + Environmental Allergies

Yes, it’s possible to have the worst of both worlds! As we mentioned above, some pets with environmental allergies can develop food allergies, so you may find it beneficial to incorporate various methods of management. This can include finding the right food, addressing the environmental exposure, and prudent use of treatments and medications when necessary (7,13,14).

4. Parasites (and Parasitic Allergies)

Gross as it may seem, this one is important: make sure you can rule out internal and external parasites and have an effective parasite management program for pets with suspected or confirmed allergies (7,8,10). Parasite elimination can be simple and may completely solve your pet’s itchy problem! That being said, many pets with atopy or other allergies can also be sensitive to insect bites, which can make the problem even worse if it isn’t managed! (4,5,6). Even worse, it’s possible for pets with flea allergies to lose almost all their coats from just one flea bite! (And yes, we have fleas all year round in the lower mainland!)

If you can’t sure that fleas, mites, mange, or other general insect allergies are not to blame for your pet’s symptoms, you may just end up chasing your own tail looking for a solution.

5. Anaphylaxis

If you or someone you know carries an Epipen (or an equivalent) for a severe allergy, then you might know anaphylaxis is an EMERGENCY. If left untreated, it can be fatal—and quickly. Anaphylaxis is characterized by shock, when the body has an abrupt drop in blood pressure, in this case due to an extreme allergic reaction (16).

Some of the first symptoms you might see in a pet going into shock could be:

  1. Extreme lethargy

  2. Weakness or collapsing

  3. Pale gums

  4. Difficulty breathing or rapid breathing

  5. Elevated heart rate

  6. Vomiting and/or diarrhea

  7. Swelling (particularly in the face)

  8. Hives and itchy skin (16).

If you suspect your pet is going into anaphylaxis, you need to get them to an emergency veterinary hospital immediately. Some pet owners even carry an Epipen prescribed for their pets if they are particularly at risk (15,16).

While this type of allergy in pets is rare, it’s often caused by insect bites or stings, reptile venom, heartworm, opiates, vaccines, blood-based products (like transfusions), and—even more rarely—food (16,24).

6. Not An Allergy at All

You might already be pulling out your hair trying to figure out how to tell the difference between the various types of allergies or intolerances. If that's the case, we're sorry to be the bearer of bad news because it gets even trickier: some diseases and conditions can present similarly to allergy conditions. Jumping straight to the conclusion of allergies can cause you to overlook other pertinent options like leaky gut, dysbiosis, maldigestion/malabsorption conditions, stress and anxiety-related conditions, inflammatory bowel disease (IBD), metabolic disorders like hypothyroidism and Cushing's disease, or simply a poor diet causing vitamin and/or mineral deficiencies (4,11). These conditions can cause allergy-like symptoms like vomiting, diarrhea, itchy skin, dull, dry, flaky coat, darkened/pigmented skin, and hair loss!

If your pet starts displaying these issues, it's important to be patient with your vet, as they may need to run multiple diagnostics to determine the cause. As much as you may want a quick fix to your pet's discomfort, ruling out other diseases can save you significant time and money and lead to a more satisfying and long-lasting solution.

Allergies in Cats; Types of Allergies and What They Look Like

So What Now?

Noticing these changes isn’t particularly difficult—the challenge becomes determining what could be causing the reaction, especially since so many allergies and non-allergy diseases have similar presentations. Testing for allergies might solve the mystery, but the type of test you use matters, and not all tests are equal. Unfortunately, this means that taking every possible route to get to the bottom of your pet’s specific allergies may not always be worth it. Check back for part two on allergy testing as we weigh the pros and cons of different tests!


Want to Check Our Sources?

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  2. Griffin CE. Dermatologic Diet Trials: Mistakes & Tips (SA092). Western Veterinary Conference 2020, Animal Dermatology Group, San Diego, CA, USA - Grif

  3. Brooks W. Immunotherapy for Allergies in Dogs and Cats. Published 11/20/2006, reviewed/revised 05/11/2021. Accessed on Jan 25, 2022 - VetPart

  4. Hensel, P., Santoro, D., Favrot, C. et al. Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification. BMC Vet Res 11, 196 (2015). - BCVet

  5. The VIN Dermatology Consultants. Atopic Dermatitis in Dogs. Published 09/15/2003, reviewed/revised 04/21/2021. - VP1

  6. Brooks W. Allergies: Atopic Dermatitis (Airborne) in Dogs and Cats. Published 01/01/2001, reviewed/revised 01/05/2022. - VP2

  7. Werner Resnick A. Food Allergy: Dr. Google Debunked. Wild West Vet 2019. Accessed at members page. -DrG

  8. Mueller, R.S., Olivry, T. Critically appraised topic on adverse food reactions of companion animals (4): can we diagnose adverse food reactions in dogs and cats with in vivo or in vitro tests?. BMC Vet Res 13, 275 (2017). - Mue

  9. Brooks W. Food Allergies in Dogs and Cats. Published 01/01/2001, reviewed/revised 06/11/2021. - BWF

  10. Brooks W. Itch Relief for Dogs and Cats. Published 01/01/2001, reviewed/revised 06/21/2021. - BWI

  11. Tater K, C Laporte. Diagnosing Cutaneous Adverse Food Reactions (Food Allergies). Published March 23, 2021 - ??? - Tater

  12. White SD, KA Moriello. Allergies in Dogs. Merck Veterinary Manual Reviewed/revised Jun 2018, last modified Sep 2020. - Merck

  13. Tater K, C Laporte (revised) Food Allergy (Canine). On VINcyclopedia of Diseases. Published 07/07/2012 - FAC

  14. Tater K, C Laporte (revised) Food Allergy (Feline). On VINcyclopedia of Diseases. Published 07/08/2012 - FAF

  15. Dell D. Definitions For Atopy, Contact Dermatitis, And Environmental Allergy. 11/06/2017. VIN Members discussion boards - VINDisc

  16. Wurlod V. How to Diagnose Canine Ananphylaxis in Your Emergency Room (SA129). Western Veterinary Conference 2020. Baton Rouge, LA. - VINana

  17. 17. Lieberman JA, Sicherer SH. Diagnosis of food allergy: epicutaneous skin tests, in vitro tests, and oral food challenge. Curr Allergy Asthma Rep. 2011 Feb;11(1):58-64. doi: 10.1007/s11882-010-0149-4. PMID: 20922509. - PM1

  18. 18. Wünhrich B. Unproven techniques in allergy diagnosis. J Investig Allergol Clin Immunol. 2005;15(2):86-90. PMID: 16047707. -PM2

  19. Coyner K, Schick A. Hair and saliva test fails to identify allergies in dogs. J Small Anim Pract. 2019 Feb;60(2):121-125. doi: 10.1111/jsap.12952. Epub 2018 Oct 29. PMID: 30371955. - HairSaliva

  20. Cafasso J. How to Tell if you have a Food Allergy. Nov 28, 2018. - HL

  21. Niggemann, B. and Grüber, C. (2004), Unproven diagnostic procedures in IgE-mediated allergic diseases. Allergy, 59: 806-808. - Nigg

  22. Roudebush Philip, W. Grant Guilford, Hilary A. Jackson. Adverse Reactions to Food. In: Small Animal Clinical Nutrition. Mark Morris Institute, 5th ed. Ch 31 pp 609-635, Jan 1, 2010. - SACN

  23. The Microbiome - AnimalBiome. Accessed on Jan 31, 2022 - AB references, and possibly

  24. 24. Dodds, WJ, DR Laverdure. Canine Nutrigenomics: The New Science of Feeding Your Dog for Optimum Health. Dogwise Publishing, Jan 13, 2015 - Dr Dodds

  25. Dog Insider Website. Accessed on Jan 10, 2022.

  26. 5Strands Website. Accessed on Jan 10, 2022.

  27. Mondo E , Giovanna Marliani, Pier Attilio Accorsi, Massimo Cocchi, Alberto Di Leone. Role of gut microbiota in dog and cat’s health and diseases. Open Vet J. 2019 Jul-Sep; 9(3): 253–258.

  28. Dodds WJ. Diagnosis of Canine Food Sensitivity and Intolerance Using Saliva: Report of Outcomes. Journal of the American Holistic Veterinary Medical Association (JAHVMA). Volume 49, Winter Issue, 2017/2018.


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