Dog Allergies in Spring in Illinois: Timing, Triggers, and How to Help Your Dog

Spring in Illinois brings warming temperatures, blooming trees, and a surge of pollen that can make life uncomfortable for dogs with seasonal allergies. If your dog starts scratching more, licking their paws obsessively, or developing recurring ear infections right around the time the weather turns, spring allergies are a likely culprit.

You’re not alone in dealing with this. Pet insurance company Trupanion reports a 27% increase in allergy claims for insured pets in Illinois in 2023 compared with 2019. Understanding what’s driving your dog’s symptoms — and what you can do about them — makes a real difference in their comfort throughout the season.

Key Insight: Dog allergies in Illinois are on the rise. Knowing the local pollen calendar and your dog’s specific triggers puts you ahead of the problem before symptoms peak.

When Does Spring Allergy Season Start for Dogs in Illinois

Illinois winters are cold enough to keep pollen dormant for several months, which gives dogs a seasonal break. But that relief ends earlier than many owners expect. Spring is tree allergy season in Illinois. Depending on the weather, it can start in late February, but it can also be delayed until March.

Both dogs and cats suffer from springtime allergies, most commonly when trees begin to pollinate. In Illinois, the first tree pollens typically come from species like maple, elm, and cedar — trees that release pollen well before they leaf out, meaning your dog can be exposed even on days that don’t feel fully like spring yet.

The tree pollen to watch out for in Illinois includes hickory, oak, ash, willow, cedar, maple, walnut, and mulberry. As spring progresses into late April and May, grass pollen takes over. In the summer, the main pollen comes from grasses. Kentucky blue, timothy, orchard, and rye grasses commonly contribute to grass pollen allergies in the Midwest.

Allergy season in Illinois usually starts in February or March and ends after the first frost of winter. The worst months are typically April, May, June, and September. For dogs with multiple sensitivities, this can mean months of continuous exposure with very little relief in between.

Pro Tip: Track local pollen counts through a resource like the National Allergy Bureau or weather apps that report daily pollen levels. On high-count days, shorten outdoor time and wipe your dog down thoroughly when they come inside.

What Causes Dog Allergies in Spring in Illinois

Spring allergies in dogs are almost always environmental in origin. The primary culprits behind springtime allergies in dogs include pollen from trees, grasses, and weeds, which can cause atopic dermatitis or airborne allergies. This condition — canine atopic dermatitis — is one of the most common chronic skin conditions diagnosed in dogs.

What makes Illinois particularly challenging is the variety of allergens active at different points in the season. Other environmental factors such as mold, dust mites, and even the dander of people or other animals can exacerbate your dog’s allergic reactions. Mold spores also become more active in spring as decomposing leaf litter and wet soil warm up.

It’s worth knowing that dogs absorb allergens differently than humans do. Pets affected by seasonal allergies are frequently observed exhibiting skin-based symptoms, because dogs’ immune systems contact the allergens mainly via a skin route, with the respiratory system playing a much smaller role. This is why itching and skin inflammation are the dominant signs in dogs, rather than sneezing and watery eyes.

While seasonal allergies tend to peak when plants are in bloom, allergic reactions may persist even after blooming is over because allergens remain on the surfaces of grass and in the home environment. In central Illinois, corn pollen presents a problem for allergic pets during harvest time, extending the allergy burden well into fall for some dogs.

Fleas are another spring trigger worth mentioning. Depending on your geographic location, fleas can be more active in the spring because of the warmer weather. This heightened activity can lead to allergic reactions in some dogs, a condition known as flea allergy dermatitis. Keeping your dog on year-round parasite prevention is an important part of managing spring allergy season in Illinois.

Signs Your Dog Has Spring Allergies in Illinois

Recognizing allergy symptoms early helps you act before secondary infections develop. The tricky part is that many seasonal allergy symptoms are similar to those of other conditions, so it’s important to be aware of the symptoms and know what you can do to help your dog and when you should see your veterinarian.

The most common signs to watch for include:

• Excessive scratching, licking, or chewing — especially around the paws, belly, face, and ears. Seasonal allergies may present as itchy skin in many dogs. This skin will usually be on their feet and legs, since these areas are exposed to pollen more than the rest of your dog’s body.
• Paw licking and chewing — one of the most consistent indicators of environmental allergies, as dogs absorb pollen through their paw pads during walks.
• Recurring ear infections — dogs with allergies are significantly more prone to yeast and bacterial ear infections that may flare each spring.
• Red or inflamed skin — often visible on the belly, inner thighs, and between the toes.
• Watery or red eyes — watery or red eyes are very common in dogs with allergies. These visible symptoms can also occur in dogs who have suffered eye trauma or who have an infection in the eye. If both eyes are red and watery, it’s more likely allergies than an injury or illness.
• Sneezing and coughing — sneezing is a common symptom of seasonal allergies in dogs. However, dogs also sneeze for many other reasons, so sneezing alone isn’t necessarily indicative of allergies. Look for other symptoms along with sneezing to help you be sure.
• Hot spots and skin infections — dogs with allergies might compulsively chew on their skin, which can lead to obsessive licking that results in raw, exposed areas known as hot spots. These areas can quickly become infected if left untreated.
• Scooting or anal gland issues — scooting and licking around the rectum is a very common issue noted with allergic dogs. The anal glands can become inflamed due to allergies.

Important Note: Owners should contact their veterinarian if there are any clinical signs associated with allergy, but especially if there is hair loss, odor, or redness to the skin, as this may indicate a skin infection that is secondary to the allergic skin inflammation.

You may also want to explore other seasonal wildlife activity in Illinois that could contribute to outdoor irritants. Illinois is home to a variety of insects and plants that become more active in spring, including several bee species and caterpillars whose hairs and secretions can cause contact reactions in sensitive dogs.

Which Dog Breeds Are Most Prone to Spring Allergies

Any dog can develop seasonal allergies, but certain breeds have a well-documented genetic predisposition to atopic dermatitis. This increased risk is thought to be partly due to inherited genetic factors that affect the immune system, though environmental influences also play a role.

If you own one of the higher-risk breeds and live in Illinois, starting allergy management proactively — before the season peaks — can make a meaningful difference in your dog’s comfort.

Atopic dermatitis in dogs typically first appears between 1 and 3 years of age. If your dog is in this age range and begins showing seasonal symptoms for the first time, it’s worth scheduling a veterinary evaluation rather than waiting to see if the symptoms resolve on their own.

Any dog, purebred or mixed, can develop allergies. Mixed-breed dogs are not immune, and if your dog carries genetics from any of the higher-risk breeds above, they may inherit similar allergic tendencies. Breed is a useful risk indicator, but it should never be used to rule out a diagnosis.

If you’re curious about how spring allergies affect dogs in neighboring states, you can compare notes with our guides on dog allergies in spring in Indiana or review how the season unfolds for dogs in Wisconsin and Missouri. You can also read about dog allergies in spring in Arkansas and dog allergies in spring in Alabama for comparison.

How Vets Diagnose Seasonal Allergies in Dogs in Illinois

Diagnosing seasonal allergies in dogs is a process of elimination as much as it is direct identification. Because diagnosing allergies in companion animals can be quite difficult, veterinarians will often start by ruling out all other possible causes of an itch, such as parasites or food allergies.

A typical diagnostic process with an Illinois veterinarian will include several steps:

1. Physical exam and history review — the process typically starts with a thorough examination and a detailed discussion about the symptoms you’ve noticed. Understanding your dog’s daily routine and environment can provide important clues about potential allergens. You may be asked about changes in their behavior, grooming habits, or whether symptoms worsen after spending time outside.
2. Parasite ruling out — flea allergy dermatitis must be excluded first. Your vet may recommend flea prevention even if you haven’t seen fleas, since a single flea bite can trigger a significant reaction in sensitive dogs.
3. Food allergy trial — some allergies arise when the pet develops hypersensitivity to the protein in their diet. In these cases, a diet trial is implemented, replacing the protein source with either a prescription hydrolyzed protein diet or a novel protein diet for 8 to 12 weeks. By the end of the diet trial, the pet should be symptom-free if the protein was the culprit. If the previous diet is then restored and the symptoms return, a food allergy diagnosis is confirmed.
4. Blood testing — a blood test, such as Heska’s Allercept or Nextmune’s Pet Allergy Xplorer, is performed by your vet to determine what environmental allergens your dog is most allergic to based on where they live.
5. Intradermal skin testing — intradermal skin testing is performed by a veterinary dermatologist. It involves injecting small amounts of allergens into the skin and monitoring for reactions, which helps identify the specific triggers to include in the immunotherapy formulation.

Pro Tip: The University of Illinois College of Veterinary Medicine in Urbana offers dermatology services and is a respected resource for Illinois dog owners dealing with complex or unresolved allergy cases.

Your dog’s medical history, including any previous allergic reactions, also provides valuable insight into their condition. Bringing notes about when symptoms first appeared, what season they worsen in, and what you’ve already tried will help your vet work through the diagnostic process more efficiently.

How to Treat Spring Allergies in Dogs in Illinois

Though seasonal allergies in dogs cannot be cured, they can be managed to help make your dog more comfortable. A multimodal approach — meaning a combination of different therapies — is usually the best way to help a dog with skin allergies. Goals of treatment include strengthening the skin barrier, managing itch, and preventing secondary skin infections.

Your vet in Illinois may recommend one or more of the following treatment options:

• Apoquel (oclacitinib) — an oral medication that’s among a new generation of highly effective anti-itch medications for dogs, blocking the itch right at its source, quickly and safely.
• Cytopoint — an injectable treatment that takes effect within one to three days and lasts for one to two months. It’s a good option for dogs who struggle with daily oral medications.
• Steroids (short-term) — steroids like prednisone or prednisolone might be prescribed short-term for severe allergy cases. Steroid use increases hunger, thirst, and urination. Long-term steroid use may weaken the immune system, cause Cushing’s disease, and contribute to diabetes, so systemic steroids should only be used for short-term control of symptoms.
• Allergy immunotherapy (allergy shots) — if your dog’s allergies are persistent, allergy shots might be the answer. This treatment helps desensitize your dog to specific allergens over time, providing lasting relief and helping them build a tolerance for seasonal triggers.
• Medicated shampoos and topical treatments — frequent bathing with a hypoallergenic shampoo can be soothing to itchy, inflamed skin. Some shampoos are available over the counter, while others may require a prescription. Bathing also removes allergens from the skin and coat.
• Omega-3 fatty acid supplements — omega-3 fatty acids are often used in combination with other treatments for dogs with itchy skin due to seasonal allergies. These fatty acids are important components of cells and are thought to improve the skin barrier.
• Ear infection treatment — ear medications such as Easotic, Mometamax, Posatex, and Tresaderm are prescribed to treat bacterial and/or yeast infections in a dog’s ears. After treatment, make sure to schedule a follow-up appointment with your veterinarian to recheck that the infection has resolved.

Common Mistake: Giving over-the-counter medication to pets without a veterinarian’s approval is not recommended. Over-the-counter antihistamines may not be effective on allergic pets, and certain decongestants can be toxic to pets. Always check with your vet before giving any human medication to your dog.

For dogs with known spring allergies, the anti-itch medication typically is started prior to the start of the allergy season and continued one month past when the allergy season ends. Starting treatment in late February or early March — before Illinois tree pollen peaks — often produces significantly better outcomes than waiting until symptoms are already severe.

You can also learn how dog owners in other states manage similar challenges. Our guides on dog allergies in spring in Georgia and dog allergies in spring in Colorado cover state-specific timing and treatment approaches.

How to Reduce Your Dog’s Exposure to Spring Allergens in Illinois

Medication works best when paired with practical steps to reduce how much pollen and mold your dog encounters. In Illinois, where the spring allergy window stretches from late February through June, consistent daily habits make a noticeable difference.

After every outdoor outing:

• Since pollen and dust cling to your dog’s fur and paws, wiping them down with a damp cloth or pet wipes after walks can help reduce allergy flare-ups.
• Bathing affected pets one to two times per week with a shampoo specified by the pet’s veterinarian can decrease allergen accumulation on the coat.
• Pay special attention to the paws, belly, and face — areas with the most direct pollen contact.

Managing outdoor time:

• If you know the pollen count is high for your area on a given day, keep your dog inside unless it’s to relieve themselves. This will limit their exposure to the allergens in the air and can help reduce their symptoms.
• Pollen counts are typically highest in the morning, so scheduling walks for late afternoon or after rain can reduce exposure.
• If spending time outside, remove any overgrown shrubs or weeds around your home that can hold pollen or mold.

Inside the home:

• Clean your home regularly and thoroughly to eliminate dust and pollen that irritate your dog’s allergies. Regular, thorough cleaning includes frequent dusting, vacuuming all carpeted areas, cleaning and replacing air filters, and laundering linens, including your dog’s bedding.
• Humidifiers and air purifiers can help dogs with seasonal allergies. Run the device close to where your dog sleeps so they can have the greatest benefits from it.
• Keep your pet on year-round flea and tick preventatives. Even just one flea bite can exacerbate allergy symptoms.

Pro Tip: Wash your dog’s collar, leash, and harness regularly during allergy season — these items collect pollen on every outdoor outing and bring it back into your home and onto your dog’s skin.

Illinois’s diverse spring wildlife can also introduce contact allergens. Dogs exploring areas with spiders or frogs may encounter additional skin irritants in wet, grassy environments. Keeping your dog on marked paths during peak allergy season limits unnecessary contact with ground-level allergens.

When to See a Vet About Your Dog’s Spring Allergies in Illinois

Some degree of seasonal itching can be managed at home, but there are clear situations where veterinary care is the right call. If your dog’s allergies are severe, persistent, or causing secondary infections, professional veterinary care is essential.

Contact your veterinarian promptly if you notice any of the following:

• Symptoms that don’t improve after a week or two of home management
• Hair loss, skin odor, or visible redness — signs of a possible secondary skin infection
• Recurring ear infections, especially if they’re happening each spring
• Hot spots or open sores from excessive scratching or chewing
• A young dog (under 3 years old) showing allergy symptoms for the first time
• Symptoms that seem to be worsening year over year

In-person veterinary care is required not only for diagnosing and treating allergies but also for preventing secondary infections that can arise from constant scratching and skin breakdown. Your vet can also help you develop an allergy management plan tailored to your dog’s specific needs, helping them enjoy the spring season with minimal discomfort.

Seek emergency veterinary care immediately if your dog shows signs of a severe allergic reaction. Any signs of anaphylactic shock should be treated as an emergency. If your dog has swelling of the face or snout or if they are struggling to breathe, take them to receive emergency veterinary care.

Key Insight: Based on a pet’s history, an owner may already know that the dog has allergies every spring and should create a proactive strategy with their veterinarian to limit the severity of the clinical signs. Scheduling a pre-season appointment in late winter — before the first Illinois tree pollens release — gives you time to have medications ready before symptoms begin.

Illinois dog owners dealing with moderate to severe or unresolved allergies can ask their vet for a referral to a veterinary dermatologist. If your dog’s allergies are severe, recurring, or not well-controlled with standard medications, ask your vet for a referral to a veterinary dermatologist. These specialists can perform intradermal skin testing and formulate a customized immunotherapy protocol that targets your dog’s specific allergens — the closest thing to a long-term solution that currently exists for canine atopy.

For additional state-by-state context on managing spring dog allergies, explore our guides on dog allergies in spring in Connecticut, dog allergies in spring in Delaware, dog allergies in spring in California, and dog allergies in spring in Florida. Illinois bird watchers with dogs may also find it helpful to know which outdoor environments carry the highest pollen loads — our guides on hawks in Illinois, owls in Illinois, and woodpeckers in Illinois can help you identify the wooded and grassy habitats where pollen exposure tends to be highest.