What are allergies?
Allergies occur when the body's own immune system reacts to a harmless substance such as pollen, certain foods etc. When an allergy occurs to a substance, the substance is known as an allergen.
Usually, the immune system would recognise the substance as harmless and ignore it, however in certain individuals, their immune system becomes hypersensitive.
Proteins known as antibodies are produced by the body in response to foreign invaders such as infections by bacteria, viruses, parasites. There are different types of antibodies (IgA, IgD, IgE, IgG and IgM). In the case of allergies, IgE is involved. Each allergic substance will have it's own specific IgE antibodies, so you may develop IgE antibodies for cat dander, rapeseed pollen etc.
IgE antibodies bind to the surface of cells known as mast cells and basophils. These cells are found throughout the body but are particularly abundant in areas close to the external environment such as the nose, throat, lungs. Both cells are filled with granules and release a substance known as histamine.
When an allergic person is exposed to Fel D1, the IgE antibodies bound to the surface of the mast cells and basophils recognise this foreign invader and trigger the cells to release their granules, including histamine into the blood. This, in turn, causes capillaries to dilate, increasing permeability, lowers blood pressure, contraction of the smooth muscles and accelerates the heart rate.
The actual cause of allergies to cats is predominantly a glycoprotein known as Fel D1. This is secreted by the cat's sebaceous glands found just beneath the skin, and to a lesser degree in the cat's saliva. Fel D4 can also cause allergies in humans, but to a lesser degree. We all know that when a cat grooms himself, he licks his fur, transferring saliva from the tongue to the coat. A cat is constantly shedding his fur into the environment. Leaving hairs on the floor, furniture, clothing etc. Dander consists of fine particles of your cat's skin that is also constantly being shed into the environment. Due to the minute size of dander particles, it can remain airborne for several hours. It sticks to soft furnishings, walls, clothing, carpets etc. This is why an allergic person may suffer a reaction even if they are not in direct contact with a cat. Just being in the environment can be enough to trigger an allergic response. It is believed that between 2 - 15% of the world's population are allergic to cats.
The first exposure to an allergen doesn't provoke an allergic response, it takes multiple exposures for this to occur as antibody levels increase. So, unfortunately, you may adopt a cat and be fine living with him and over time (months to years) develop an allergy.
The skin of a kitten is more supple than that of an adult and they are less likely to cause allergies. Some breeds of cat are said to be hypoallergenic, which is covered later in the article. Entire male cats also produce more Fel D1 protein than neutered males or female cats.
What are the symptoms of allergy to cats?
Common symptoms associated with allergies to cats include:
- Sneezing and/or a runny nose (allergic rhinitis)
- Red, itchy or swollen eyes
- Itchy throat
These symptoms make sense. Remember, the mast cell's job is to fight against invaders, especially parasites. One way this is achieved is by causing the body to release mucous which pushes out the invaders (hence the runny nose).
As we said above, histamine also contracts the smooth muscles, including the muscles that surround the bronchioles, causing them to constrict, making breathing more difficult.
Diagnosis of cat allergies:
Before you blame the cat, it is worth visiting your doctor and requesting an allergy test, to determine for sure that it is the cat and not something else (such as dust mites).
An allergy test usually involves a skin prick test. A tiny prick containing the allergen is placed on the skin of the forearm. If the patient is allergic, redness, swelling and itching will occur.
Image Adam Gerhard, Flickr
How to treat cat allergies:
There needs to be a twofold approach when addressing cat allergies. Reduce exposure in the environment, and medical treatment.
First for the environment:
There are certain steps you can take to reduce exposure to cat allergens. It should be stated that you can reduce but not eliminate allergens from the home.
Cleaning is a key component to reducing exposure to hair and danders in the house.
- Carpet harbours cat fur and dander - Floorboards or tile are much better for pet owners. They can be regularly damp mopped to remove danders.
- Keep cats out of the bedroom - While you can't completely prevent the spread of cat hair and dander around the house, keeping bedrooms pet free can at least help reduce this. Remember to keep bedroom doors closed.
- Bathe your cat - Two to three times a week helps reduce the amount of Fel D1 on your cat's skin.
- HEPA (high-efficiency particulate air) filters - Install air purifiers with HEPA filters. These filters trap small particles (such as cat dander) in the environment. Many vacuum cleaners now come with HEPA filters.
- Desex your cat - Entire male cats have higher levels of Fel D1 than desexed males or females.
- Wipe down surfaces - Using a damp cloth on surfaces will help prevent the spread of cat hair and dander into the environment.
- Regularly wash soft furnishings - Cushions, curtains are a harbour for cat dander and fur. Washing regularly can go a long way to reducing exposure to allergens. The temperature should be at least 55°C (130°F).
- Litter trays - Cat urine also contains allergens, so if you are allergic, get another member of the family to clean the trays. Litter trays should be cleaned outside.
- Wash your hands - Every time you handle your cat, or his bedding, make sure you wash your hands afterwards.
Medical treatment for allergies to cats:
- Antihistamine (such as Benadryl) are drugs which inhibit the action of histamine.
- Decongestants - Help by reducing swelling in the nasal tissue, relieving stuffiness.
- Immunotherapy (allergy shots) - This involves periodic injections of the allergen in ever increasing doses in order to "desensitise" your immune system to the allergen in question. Immunotherapy can take months or years to work, and unfortunately, desensitisation isn't always achieved.
- Vaccine - The good news is that it looks like there may be a vaccine on the horizon for cat allergy sufferers. Trials are currently underway to test the efficiency of this vaccine.
What about hypoallergenic breeds of cat?
The jury is still out as to whether certain breeds of cat are hypoallergenic or not. Some individuals do report less of an allergic reaction to certain breeds, others report no difference. Some breeds reported to be hypoallergenic include:
- Devon Rex
- Cornish Rex