How To Tell What’s Really Making Your Dog Itchy
If your dog’s constantly licking their paws, scratching at their ears, or sporting red, irritated skin, it’s easy to assume it’s a food allergy. And sometimes it is. But more often than not, the culprit is actually environmental.
In fact, food allergies are estimated to make up only 10–20% of allergic reactions in dogs, while the majority are caused by things like pollen, dust mites, mould, and grasses.
So how do you tell the difference?
What is a food allergy in dogs?
A food allergy is an overreaction of the immune system to a particular protein in your dog’s diet. The most common offenders? Beef, chicken, dairy, lamb, and wheat — proteins used widely in commercial dog foods.
Signs of a food allergy can include:
- Chronic ear infections
- Itchy skin (often around the face, paws, and belly)
- Vomiting or diarrhoea
- Excessive gas or soft stools
Importantly, these symptoms tend to be year-round and consistent, because your dog is typically eating the same protein every day.
What actually happens during a food allergy?
When a dog has a food allergy, their immune system mistakes a harmless food ingredient for a threat. In response, it produces antibodies (immunoglobulins E) to neutralise that substance. Then, every time your dog eats even a small amount of the allergen, their body releases inflammatory chemicals like histamine, prostaglandins, and leukotrienes — triggering the allergic reaction.
While proteins are the most common cause (especially beef, chicken, lamb, and dairy), some dogs can also react to eggs, soy, wheat gluten, or even rarely, ingredients like carrots or potatoes. Additives and artificial colourings can also play a role, depending on the dog.
The takeaway? Any ingredient has the potential to be an allergen — but most often, it’s common proteins found in everyday pet food.
What about environmental allergies?
Environmental allergies — or “atopic dermatitis” — are caused by airborne allergens like pollen, mould, grasses, or dust mites. These are more like hay fever in humans (but with a lot more paw chewing).
Environmental allergy signs often include:
- Seasonal itching (worse in spring/summer)
- Chewing or licking paws after being outside
- Rubbing face on furniture or carpet
- Redness or hair loss on the belly or legs
Unlike food allergies, these symptoms may fluctuate with seasons or worsen after walks in certain areas.
How can you tell the difference?
This can be tricky and the best thing you can do it consult with your vet. The gold standard for diagnosing a food allergy is an elimination diet — feeding your dog a novel, single-protein food (potentially without grains or other possible allergens) for 8–12 weeks and watching for improvement. If symptoms go away and return when the old food is reintroduced, it’s likely a food allergy.
That said, most skin allergies in dogs are not caused by food. But food is often investigated first — because unlike pollen, you can control what’s in their bowl.
For environmental allergies, your vet may suggest skin testing or blood tests to pinpoint allergens, especially if symptoms persist despite a clean, simple diet.
Where hypoallergenic, novel proteins come in
If your vet suspects a food allergy, switching to a novel protein — like insect protein — can help break the cycle. Novel proteins are ones your dog hasn’t been exposed to before, making them less likely to trigger an immune response. They’re also ideal for elimination diets.
And if your dog has both types of allergies? A hypoallergenic diet can help reduce inflammation and support their immune system while you manage environmental triggers with other treatments.
Final thought
Not every itch is a food allergy. But when it is, a gentle, novel protein diet can be a game-changer. Whether you’re navigating environmental triggers, diet issues, or a mix of both, understanding the root cause is the first step to helping your dog feel comfortable in their skin again.
References
Miller, W.H., Griffin, C.E., & Campbell, K.L. (2013). Muller & Kirk’s Small Animal Dermatology (7th ed.). Elsevier.
Verlinden, A. et al. (2006). Food allergy in dogs and cats: a review. Critical Reviews in Food Science and Nutrition, 46(3), 259–273.
Olivry, T. et al. (2010). Towards a comprehensive understanding of canine atopic dermatitis. Veterinary Dermatology, 21(2), 123–132.
American Kennel Club. (n.d.). Dog Allergies: Symptoms and Treatment. Retrieved from https://www.akc.org/expert-advice/health/dog-allergies-symptoms-treatment/
