Why Is My Dog Scratching So Much? Late-Summer Allergies in Burlington

The phone starts ringing about this every August. Same worry, different dog.

“He won’t stop scratching. Was fine in June.” A pause, then a collar jingling as the dog goes at his ear again.

We hear it at the front desk on Brant Street more than almost anything else once the humid weeks settle over Burlington. A dog comfortable all spring is suddenly licking his paws raw and rubbing his face along the couch at 2 a.m.

Usually, the calendar changed.

Most late-summer itching in Burlington dogs traces back to allergies or fleas, which is why the time of year matters so much. According to Cornell’s Riney Canine Health Center, atopic dermatitis (an allergic skin disease) may affect as much as 10 to 15% of dogs, and its itch has a seasonal component in roughly 40 to 75% of cases.

If this is happening right now and your dog has broken the skin, is swollen around the face, or is so distressed they won’t settle, eat, or sleep, call us at (905) 336-4002. After hours, use our after-hours care page or your nearest emergency hospital. For a suspected poison or reaction to a topical product, the Pet Poison Helpline is 855-764-7661.

Why is my dog scratching so much but has no fleas?

A dog can itch intensely with no visible fleas at all, and environmental allergies are a common reason. Cornell’s Riney Canine Health Center reports that typical allergens include many pollens and molds, dust mites, and dander, and affected dogs respond by scratching behind their elbows, licking and chewing their feet, and rubbing their faces.

Some dogs are so sensitive that a single flea bite sets off days of itching.

The Merck Veterinary Manual describes flea allergy dermatitis as a hypersensitivity to antigens in flea saliva, so the flea may be gone by the time you look.

Environmental allergy is a different problem. The Merck Veterinary Manual explains that atopic dermatitis is driven by an immune (IgE) response to environmental, food, or microbial allergens in dogs that are genetically prone to it.

Nothing is biting your dog here. Their own immune system is overreacting to something ordinary in the air, so if you’ve combed and cleaned and your dog is still miserable, have us take a look rather than assuming it’s dry skin.

Why does my dog scratch more in late summer and fall?

Late summer stacks two triggers on top of each other in Halton, since ragweed pollen peaks while warm, humid weather keeps fleas active. The Government of Ontario’s weed guide notes that common ragweed, a leading pollen allergen, flowers from August to October, which overlaps exactly with the weeks we hear the most about scratching.

Think about what a Burlington dog walks through in September. Roadside grasses gone to seed, ragweed along the trail edges, damp leaf litter in the ravines.

The Merck Veterinary Manual notes that the itch of atopic dermatitis can be seasonal, non-seasonal, or non-seasonal with seasonal flares. That’s why a dog can sail through winter and fall apart in August.

Fleas pile on during the same stretch. The Companion Animal Parasite Council reports that flea development depends on temperature and humidity, with adult fleas usually all emerged by day 13 at around 24 C and 78% relative humidity.

A muggy southern Ontario late summer is close to ideal for them.

What are the signs my dog has seasonal environmental allergies?

The pattern usually shows up in the paws, face, and ears, and it comes and goes with the season. Cornell’s Riney Canine Health Center reports that dogs with environmental allergies react by scratching behind their elbows, licking and chewing their feet, and rubbing their faces, and that the itch often follows a seasonal rhythm tied to the allergens involved.

Watch where your dog focuses. The Merck Veterinary Manual reports that the most frequently affected areas in canine atopic dermatitis are the paws, face, ears, the front-leg flexural surfaces, the armpits, and the belly.

The Merck Veterinary Manual notes that canine atopic dermatitis generally first appears between 6 months and 3 years of age, so a young adult dog who gets itchy every summer fits the typical picture. If that rhythm shows up on schedule each year and settles in the cold months, mention it when you call our allergies and dermatology team.

Can food allergies make my dog itchy, and how is that diagnosed?

Yes, food can be a cause, but it’s diagnosed differently than most people expect. The Merck Veterinary Manual explains that food allergy in dogs is identified with an elimination diet trial, not a blood or skin test, and that a literature review found a minimum of about 10 weeks may be needed to identify 95% of food-allergic patients.

Owners ask us for the allergy blood test, and the honest answer is that those tests aren’t reliable for food allergy in dogs.

The Merck Veterinary Manual is clear that dietary elimination trials remain the reference standard. That means feeding a carefully chosen novel-protein or hydrolyzed-protein diet, and nothing else, for a set stretch of weeks.

Food allergy also doesn’t follow the seasons. A dog itchy only in late summer is pointing you toward pollen, not diet.

Where do dogs with flea allergy dermatitis itch the most?

Flea allergy has a signature location: the back half of the dog. The Merck Veterinary Manual reports that in flea allergy dermatitis, itchy, crusted lesions are classically distributed over the lower back, the tailhead, and the back and inner thighs, a different map than the paws-and-face pattern of environmental allergy.

If your dog is chewing frantically at the base of the tail, fleas move up the suspect list fast.

The Companion Animal Parasite Council reports that a single female flea can produce 40 to 50 eggs per day, so a couple of hitchhikers from a Burlington backyard become a household population fast, most of it living in your carpets.

Here are the three common itch patterns we sort through in the exam room.

The reason we don’t just guess is that these overlap. A dog can have a flea allergy and an environmental allergy at once, and calming one still leaves the other.

Can scratching cause a skin infection in my dog?

It can, and that’s often what turns a mild itch into a vet visit. The Merck Veterinary Manual reports that self-trauma from scratching and biting, combined with allergic inflammation, can lead to secondary bacterial infections (pyoderma) and yeast infections (Malassezia dermatitis), which then make the dog itchier and drive still more scratching.

That loop is the reason not to wait it out. What starts as a bit of licking becomes a hot, red, sometimes smelly patch of skin.

Once bacteria or yeast take hold, the original allergy is no longer the whole story, and topical home remedies rarely close the gap.

This is where a real exam earns its keep. We can look at the skin and tell whether we’re treating an allergy, an infection, or both, and our diagnostics tools help us sort that out instead of guessing.

When should I take my itchy dog to the vet?

Call us when the itch is constant, breaking skin, spreading, or stealing your dog’s sleep. The Merck Veterinary Manual reports that atopic dermatitis cannot be cured, but in most cases it can be managed to improve the dog’s quality of life, and that management works best when it starts before the skin is badly damaged.

A little seasonal scratching is one thing, but a dog who can’t stop is another. Some signs shouldn’t wait: raw or bleeding skin, a fast-growing hot spot, swelling around the face, hair loss in patches, or a dog too uncomfortable to rest or eat.

There’s also a local reason to have a scratching dog checked in person. The Halton Region reports that all of Halton, Burlington included, is an established blacklegged tick risk area, with locally acquired Lyme disease cases rising to 28 confirmed in 2023 from 8 in 2022, and that ticks turn up almost anywhere in Ontario, including city gardens and parks.

A dog biting at their skin should be checked for parasites as well as allergies, because the two can look alike from across the room.

Does my dog need flea prevention year-round in Ontario?

The guidance is yes, all year. The Companion Animal Parasite Council recommends that all dogs receive year-round, lifelong flea control to limit infestations on the pet and prevent flea populations from establishing in the home, and while our warm months are the highest-pressure stretch, stopping in fall lets populations rebuild.

Once fleas establish in a home, most of the population lives in the environment rather than on the dog. A warm indoor Burlington winter can keep a cycle going long after the frost.

Because ticks travel the same Halton trails and yards, many owners here use a product that covers both. What’s right for your dog depends on their age, health, and lifestyle, and keeping wellness and vaccinations current is the natural moment to review it.

Frequently asked questions

What is atopic dermatitis in dogs and can it be cured?

Atopic dermatitis is an allergic skin disease. The Merck Veterinary Manual reports it is driven by an immune response to environmental, food, or microbial allergens in genetically prone dogs, and that it cannot be cured but can usually be managed for a good quality of life. Cornell’s Riney Canine Health Center calls it a lifelong condition.

Why is my dog licking and chewing its paws?

Paws are a classic allergy target. Cornell’s Riney Canine Health Center reports that dogs with environmental allergies commonly lick and chew their feet, and the Merck Veterinary Manual lists the paws among the most frequently affected areas in canine atopic dermatitis. Rust-coloured staining between the toes is often the first sign owners notice.

My dog only itches in August and September. Is that normal?

That seasonal pattern is common and points toward pollen. The Government of Ontario notes common ragweed flowers from August to October, and the Merck Veterinary Manual reports that atopic dermatitis often flares seasonally. It’s still worth a call if the scratching is intense, since a seasonal allergy can still damage skin.

Can I just use an over-the-counter product on my dog’s skin?

It’s best to check with us first. Some human and topical products aren’t appropriate for dogs, and masking an itch without finding the cause can let a secondary infection build unnoticed. The Merck Veterinary Manual notes that early management works better than treating badly damaged skin.

How is a food allergy trial actually done?

Through a strict elimination diet, not a test kit. The Merck Veterinary Manual explains that dietary elimination trials are the reference standard, and that a literature review found a minimum of about 10 weeks may be needed to identify 95% of food-allergic patients. The hard part is feeding nothing else, treats and flavoured chews included.

This article is educational and isn’t veterinary advice or a substitute for an exam. If you’re worried about your pet right now, call us at (905) 336-4002 or your nearest emergency veterinary hospital.

If your dog has been scratching more than usual as the Burlington summer winds down, you don’t have to wait it out and hope. Our team on Brant Street can look at the skin, sort allergies from fleas from infection, and get your dog comfortable again.

Request an appointment

Sources

Veterinary medical references

1. Merck Veterinary Manual, Canine Atopic Dermatitis. https://www.merckvetmanual.com/integumentary-system/atopic-dermatitis/canine-atopic-dermatitis
2. Merck Veterinary Manual, Flea Allergy Dermatitis in Dogs and Cats. https://www.merckvetmanual.com/integumentary-system/fleas-and-flea-allergy-dermatitis/flea-allergy-dermatitis-in-dogs-and-cats
3. Merck Veterinary Manual, Cutaneous Food Allergy in Animals. https://www.merckvetmanual.com/integumentary-system/food-allergy/cutaneous-food-allergy-in-animals
4. Cornell University College of Veterinary Medicine, Riney Canine Health Center, Atopic Dermatitis (Atopy). https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-topics/atopic-dermatitis-atopy

Parasite prevention guidance

1. Companion Animal Parasite Council (CAPC), Fleas Guidelines. https://capcvet.org/guidelines/fleas/

Local and public health

1. Government of Ontario, Weed Identification Guide for Ontario Crops: Common Ragweed. https://www.ontario.ca/document/weed-identification-guide-ontario-crops/common-ragweed
2. Halton Region Public Health, Increasing Risk of Tick-Borne Diseases in Halton. https://www.halton.ca/for-business/information-for-physicians/physician-notices-and-updates/2025/increasing-risk-of-tick-borne-diseases-in-halton