Grass Allergies in Dogs: Signs, Causes, and Treatment

Grass allergies in dogs are common—your dog doesn’t even need to be on the grass to experience an allergic reaction.

These allergies are more prevalent in the spring and fall, though they can occur at any time of year. They can affect your dog in varying degrees, causing itching, licking and, in severe cases, hives and difficulty breathing.

Your veterinarian can help you determine if your dog is allergic to grass, and if so, develop an appropriate treatment plan.

Treatments won’t cure the grass allergies, but they may help alleviate the symptoms.

What Are Grass Allergies in Dogs?

Grass allergies in dogs are caused by pollen associated with grasses.

Allergens (grass pollens) are absorbed by the skin and mucous membranes, causing an immune response. Grass pollens can be airborne, so your dog doesn’t have to be physically on the grass to be affected.

Grass allergies can occur at any age, but most dogs start having allergies after they are about a year old due to prior exposure to the allergens.

Grass allergies are generally worse in the spring and fall seasons, when grass pollen is more prevalent due to the variation of seasonal species. However, they may be a problem for your dog all year long.

Causes of Grass Allergies in Dogs

Grass allergies are caused by common grass pollens from grasses such as Bermuda, fescue, alfalfa, or rye. Symptoms are like allergies caused by pollens from trees (cedar, pine, oak) and weeds (ragweed, pigweed).  

Dogs who enjoy rolling in the grass can get symptoms from direct contact.

If a dog walks through an area where pollen is present and the pollen encounters a pup’s mucous membranes (nose, eyes, mouth), skin, or feet, they may experience symptoms.

Others may get symptoms from inhaling the pollen during a walk or simply from being in an area where grass pollen is present—even indoors. 

Symptoms of Grass Allergies in Dogs

Symptoms of grass allergies in dogs include: 

• Redness of the skin (erythema)

• Itchiness of the skin

• Scratching, especially at the face, armpits, and sides of the body

• Licking or chewing, especially the feet

• A rash may also appear; but due to the haircoat on dogs, redness and a visible rash may be difficult to see 

A severe allergic reaction—known as anaphylaxis—is rare. Anaphylaxis in dogs can occur within five to 30 minutes of contact with the allergen.

Symptoms of anaphylaxis in dogs may include:

• Severe hives

• Facial swelling (especially around the eyes and muzzle)

• Wheezing

• Difficulty breathing

• An increased respiratory rate

• Vomiting with blood or without blood

• Diarrhea with blood or without blood

If you think your dog is experiencing anaphylaxis or see any of the above symptoms, seek veterinary care immediately.

How Veterinarians Diagnose Grass Allergies in Dogs

To diagnose grass allergies in dogs, your veterinarian will obtain a complete history regarding the symptoms present in your dog, including symptom duration, severity, seasonality, and treatment (if any).  

Next, your  vet will perform a thorough examination of your dog’s haircoat and skin. The following will help determine a diagnosis:

• The distribution of hair loss

• Any lesions on the skin such as pimples, rashes, or dry or oily skin

• Redness (to indicate inflammation)

• Scratches or skin irritation

Sometimes, symptomatic treatment can be initiated based on clinical symptoms without any testing needed, depending on the case.

If topical or conservative treatments are not effective, further testing may be needed to rule out other causes. 

Allergy Testing for Your Dog

Your vet may be able to perform serum blood testing for grass allergies.

However, the test that provides the most accurate result for allergies is called an intradermal skin test, which is performed by a veterinary dermatologist.

The intradermal skin test is usually performed under mild sedation. One side of the dog’s abdomen is shaved, and specific allergens are injected. The area is monitored for the presence of hives, indicating an allergic reaction to the specific allergen injected in that location.

If the allergens are identified, treatment is designed specifically for each dog.  

Treatment of Grass Allergies in Dogs

The goal of treatment for grass allergies in dogs is to manage symptoms, because most grass allergies in dogs can’t be cured. Treatment is based on severity of symptoms.

Consult with your veterinarian on the best treatment for your dog.

For moderate to severe symptoms, certain therapies may be recommended, such as:

• Allergy medication—Zenrelia may be recommended by your vet. This daily oral tablet quickly controls itching and inflammation.

  • Your vet may also suggest Cytopoint (an injectable given every four to eight weeks) for your dog. These are prescription medications, so your veterinarian will determine which is best for your dog. 

• Short doses of corticosteroids—Medications such as prednisone, prednisolone, or Temaril-P contain steroids that may be used in cases of severe itch. 

  • These are by prescription only and typically should only be used short-term due to potential side effects of long-term administration. 

• Immunotherapy or hyposensitization therapy—This type of therapy consists of “micro-dosing” the pet with the allergen to build up resistance over time. It can be used if the allergens have been identified by a blood or intradermal skin test.

If symptoms are mild, the following may be recommended:  

• Bathing in a hypoallergenic or mild oatmeal-based pet shampoo—Consistent bathing will help remove the allergens before they have time to be absorbed into the skin. This may help prevent or decrease the itching. There are several brands of oatmeal shampoos available without a prescription.  

• Trying a medicated shampoo—A medicated pet shampoo is not typically sufficient for treating an active infection, but it can help prevent an infection by removing the allergens and reducing the amount of bacteria and yeast on the skin. Always talk to your vet about which medicated shampoo would be best for your dog.  

• Cleanliness after spending time outdoors—Ensuring that your dog’s feet and body are cleaned off when coming inside helps prevent licking and chewing of feet, a symptom of itching. You can use mild soap and water, aloe pet wipes, or medicated wipes that contain an antimicrobial and antifungal ingredient.   

• Antihistamines—Benadryl may be effective for watery eyes, runny nose, and sneezing, but it is usually not effective for allergic skin conditions (allergic dermatitis). Discuss dosage with your vet before giving your dog any medication, even over the counter (OTC) medications.  

• Fatty acids—Omega-3 supplements and fatty acids can help decrease a pet’s skin inflammation and help with general itchiness. 

Recovery and Management of Grass Allergies in Dogs

It’s important to determine—or at least narrow down—which grasses your dog is allergic to so that you can try to prevent symptoms.

Dogs encounter all types of grasses, including those in yards, dog parks, or fields.

It’s helpful to know which grasses are in your area, monitor symptom flare-ups, and avoid these areas when possible. 

Allergies can be managed and symptoms controlled, but you should not expect a 100% cure. If symptoms are reduced by 80% (less itching), treatment is considered successful.