Hay Fever (Allergic Rhinitis) In Cats

What is hayfever?

Medically known as allergic rhinitis, hayfever is a type of allergic reaction to pollen. Normally the immune system ignores harmless substances, but some cats develop an inappropriate immune response to pollen characterised by sneezing, watery eyes and a runny nose.

Types of allergy:

• Food – As the name would suggest, this is a food allergy and is the most common type of allergies in cats.
• Contact – This type of allergy is rare in cats; this type of allergy occurs when the cat comes into contact with an allergen, for example, wool, or medications.
• Insect – The most common cause of insect allergy is cat fleas, but other insects can also cause allergies.
• Inhalant –  Unlike in humans who tend to develop hay fever (allergic rhinitis),  most cases of inhalant allergy in cats present as skin conditions. Hay fever is a type of inhalant allergy.

Hay fever occurs when the cat’s body reacts to pollen; common allergens include grasses. Exposure occurs when the cat either inhales the pollen or licks it during grooming. Usually, the body would ignore a benign substance such as pollen; however, in some cats, the immune system mounts an unnecessary allergic response. Anything the body has an allergic reaction to is known as an allergen.

How an immune response works:

• The first step is sensitisation. So, a foreign substance enters the body (in this case pollen, via the nose), and scavenger cells known as macrophages break up the invader and display fragments of the invader on their cell walls for white blood cells (T cells).
• T-cells then secrete a chemical that activates another type of white blood cell known as B cells. These cells generate antibodies specific to that particular invader. Antibodies are known as immunoglobin E (IgE) and are attached to immune cells called mast cells and basophils. Mast cells are located in the tissues and basophils in the blood.
• The next time that particular foreign substance enters the body, the IgE cells on mast cells recognise the invader and attach to them. When this occurs, mast cells and basophils release a chemical substance known as histamine. Histamine causes capillaries in the nose to dilate (swell), causes redness, nasal secretions, swelling, and inflammation.

Allergy symptoms in cats

Clinical signs are typically seasonal, with a higher incidence in spring and summer.

• Runny nose
• Red, itchy, watery eyes
• Noisy breathing due to inflammation
• Blood may be seen in the nasal discharge after prolonged exposure due to blood vessels becoming damaged
• Some cats may develop skin conditions, including lumps and bumps, itching, redness, and swelling

Most of the above symptoms are similar to that of a cat cold or flu, but shouldn’t include fever or loss of appetite.

Diagnosis

Your veterinarian will perform a complete physical examination of your cat and obtain a medical history from you. Hay fever will be suspected if there is a history of seasonal rhinitis.

If your veterinarian suspects an allergy, it will be necessary to perform a skin prick test.  The skin prick test (SPT) is used to identify environmental allergens the cat may be allergic to. A sedative will be administered and the cat’s lateral thorax (side) is shaved and marked with a series of dots. The clinician applies a different allergen to the marked spots and gently pricks the skin with a sterile lancet so that a small amount of the allergen penetrates the skin. The first two substances are a positive histamine control which produces a raised, red wheal, and a negative control which is a saline solution the allergens are suspended in.

Treatment

Minimising contact with the allergen is the main goal as well as controlling symptoms. It is not always easy to avoid exposure to pollens. Keeping windows shut, use air filters, regularly dust can reduce exposure.

Corticosteroids: A synthetic form of steroid hormones used to treat inflammation. The veterinarian will prescribe the lowest dose possible to manage symptoms, and it will be necessary to monitor your cat closely.

Allergen immunotherapy (allergy shots): These shots expose the cat to a tiny amount of the allergen, gradually increasing the amount given; this can help the cat’s body get used to the allergen and reduce symptoms. The success rate is varied.

Medicated shampoos and conditioners: To remove pollens from the coat, which reduces the amount that the cat will inhale or ingest when it grooms. Shampoos can also help to soothe inflamed and itchy skin.

Antihistamines: Medications that block the effects of histamines and may be prescribed to offer relief to your cat. However, you must speak to your veterinarian about the appropriate antihistamine to use as not all are suitable, particularly if your cat has an underlying medical condition.

Keep the cat indoors as much as possible during the high pollen season. Pollen counts are at their highest from dawn to around mid-morning.