There are many species of ragweed plants throughout North America that put out large amounts of pollen in the fall. This pollen acts as an allergen for several species of animal, including cats. An allergic reaction occurs in an animal when the immune system treats a harmless substance (allergen) as though it were a harmful substance like a virus or bacteria. Allergies can develop at any time in your pet's life and ragweed is a common allergen in many species. Ragweed pollen is an inhalant allergy, although, in cats the allergic reaction tends to affect the skin more than the respiratory system. Skin irritation and inflammation resulting in itching is a common manifestation of ragweed allergy in cats. Treatment by your veterinarian can greatly reduce symptoms of ragweed allergy in your cat.

Symptoms of ragweed allergy in cats tend to be dermal more than respiratory, however, respiratory symptoms can occur alongside dermal reactions or independent of them. Additional ragweed allergy symptoms that may occasionally occur include a runny nose and watery eyes.

Respiratory symptoms 

There are many types of ragweed plants common throughout North America. Ragweed allergic reactions tend to be more of a problem in warmer climates, either due to the species involved or to a combination of environmental factors present in warmer areas. Ragweed is a common allergen in many species of animals including humans and is seasonal, occurring in the fall when ragweed plants put out copious amounts of wind-borne pollen. Inhaled pollen acts as an allergen causing an immune system overreaction to a harmless but foreign substance.

Your veterinarian will perform a complete physical exam and collect information on your cat's medical history to determine if an allergic reaction is likely, or if another condition may account for your pet's symptoms. Factors like geographic location, season and exposure to allergens will be taken into account. If allergy is suspected your vet will perform intradermal and serologic tests to check for reactions to allergens and check immune system functioning. Tests to check for other conditions may also be ordered. Causes of dermal reaction such as fleas and other parasites that may cause similar symptoms will need to be ruled out.

There are two main types of treatment of ragweed allergy in cats: medication and desensitization.

Your veterinarian may prescribe steroids to treat your pet's allergy. Steroids have minimal side effects in cats and are usually effective at relieving allergy symptoms. They do not, however, provide a cure for the allergy, which will return with reexposure to the allergen, requiring treatment to be repeated.

Allergen immunotherapy involves repeated desensitization of your cat to the allergen by exposure to small amounts of the allergen in a controlled environment. Multiple treatments are required in which allergen exposure is gradually increased, until the cat’s immune system is “trained” not to react to the ragweed allergen. This treatment is time-consuming and associated with an increased cost, however, it is usually effective, and if successful the allergy will not recur and require further treatment seasonally.

If your cat is treated with steroids, continuing steroid therapy and limiting your cat's exposure to ragweed pollen by keeping them indoors and vacuuming and dusting your home, will help your pet recover. Medicated baths may help reduce dermal symptoms. Additionally, a diet low in grains that can cause immune system sensitivity, may help reduce allergy symptoms in your cat. Your cat may have repeated allergic reactions seasonally that may increase over time and that will require further treatment.

Desensitization therapy will require multiple visits to your veterinarian for treatment but once completed, allergic reaction should not recur seasonally.