Introduction
Cat allergies refer to an overreaction of the immune system to proteins found in cat dander, saliva, or urine. When exposed to these allergens, a person with cat allergies may experience symptoms like sneezing, runny nose, watery eyes, coughing, wheezing, and skin irritations. Cat allergies are estimated to affect 10-15% of the population and can range from mild to severe.
Genetics are thought to play a major role in developing cat allergies. People inherit a predisposition to allergies, especially if their parents have them. Certain gene variants regulating immune responses are linked to higher risk. But environmental and other factors also contribute to determining if a predisposed person will develop a clinical allergy. This article reviews the genetic factors that may underlie cat allergies as well as other possible causes.
Symptoms
The most common symptoms of cat allergies include:
- Sneezing
- Runny or stuffy nose
- Itchy, red, watery eyes
- Facial pressure and pain from nasal congestion
- Postnasal drip
- Coughing
- Chest tightness
- Shortness of breath and wheezing
Symptoms may start within minutes or hours after exposure to cat allergens and can be mild to severe. Some people may experience anaphylaxis, a potentially life-threatening reaction. Severity of symptoms can vary based on the amount of allergen exposure and sensitivity. (Mayo Clinic, 2022).
Causes
Cat allergies are caused by an immune response to allergens found in cat dander, saliva, or urine. When someone with a cat allergy comes into contact with these allergens, their immune system identifies them as harmful and releases antibodies called immunoglobulin E (IgE). These IgE antibodies then trigger the release of chemicals like histamine that cause allergy symptoms.
The most common cat allergens are:
- Fel d 1 – a protein found in cat saliva, skin and fur. It is considered the primary allergen.
- Fel d 2 – a protein found in cat saliva and skin secretions.
- Fel d 3 – a protein found in cat saliva.
- Fel d 4 – a protein found in cat urine.
When a person with a cat allergy comes into contact with these proteins, their immune system overreacts and releases the IgE antibodies that cause the bothersome symptoms. So cat allergies are caused by an abnormal immune reaction to allergens commonly found on cats.
Some references:
https://vet.osu.edu/sites/vet.osu.edu/files/legacy/documents/pdf/education/mph-vph/allergic%20to%20your%20cat.pdf
https://www.webmd.com/allergies/cat-allergies#1
Genetic Factors
While cat allergies are not directly inherited, genetics do play a role in determining if someone is predisposed to developing allergies. Several studies have shown that allergies tend to run in families. According to the National Library of Medicine, if one parent has allergies, there is about a 50% chance that their child will develop allergies as well. If both parents have allergies, the risk goes up to 70-80% [1].
Research has identified certain genes associated with higher risk of allergies. Variants in genes related to the immune system, such as HLA-DQA1 and IL13, are linked to increased likelihood of cat allergies specifically [2]. However, environmental factors also play an important role. Having a genetic predisposition does not guarantee that someone will develop cat allergies, but it does make them more susceptible when exposed to triggers.
In families with a strong history of allergies, testing for known allergy risk genes can help assess a person’s chance of developing cat allergies. But genetics alone cannot predict with 100% accuracy, as environmental exposures and interactions are still required to trigger allergic responses.
Non-Genetic Factors
While genetics play a role, exposure to allergens is thought to be the most significant non-genetic factor in developing cat allergies. Exposure over time to cat dander and proteins in things like saliva, urine, and sebaceous glands can trigger an allergic response in those with a genetic predisposition (1). The more exposure someone has to cats, the more likely they are to develop an allergy over time.
Cross-reactivity is another non-genetic factor. People with allergies to other substances like dust mites, dogs, horses, or birch pollen are more likely to develop cat allergies due to similar proteins in cat dander (2). This cross-reactivity means the immune system recognizes similar antigens between substances.
Environmental factors like pollution, tobacco smoke, and respiratory infections are also associated with increased susceptibility to allergic diseases. Exposure to these irritants likely worsens symptoms in people with cat allergies (2).
Diagnosis
To diagnose cat allergies, doctors may use skin prick testing or blood tests. During a skin prick test, a doctor or nurse will prick the skin with small amounts of suspected allergens, including cat dander and saliva. If a raised, red bump forms at the prick site, it indicates an allergy. Blood tests like the radioallergosorbent (RAST) test measure immunoglobulin E (IgE) antibodies to specific allergens in the blood. Higher levels indicate an allergy. Skin testing is considered more accurate than blood testing.
In some cases, an allergist may recommend an oral food challenge, where a person consumes small amounts of cat allergens like proteins under medical supervision to confirm a cat allergy diagnosis. An allergist may also examine the nose and use a lighted instrument called a rhinoscope to assess nasal passages and look for signs of an allergic response.
To definitively diagnose a cat allergy, a doctor will consider medical history, symptoms, skin or blood test results, and physical examinations. Identifying allergies allows doctors to provide proper treatment recommendations.
Treatments
There are several treatment options available for people with cat allergies:
Avoidance
The most effective treatment is complete avoidance of cats. However, this may not be practical for people who live with cats. Strategies include keeping cats out of the bedroom, using high-efficiency particulate air (HEPA) filters, washing hands after contact, and vacuuming frequently [1].
Medications
Antihistamines like cetirizine (Zyrtec) or loratadine (Claritin) can help relieve allergy symptoms. Nasal steroid sprays such as fluticasone (Flonase) may also help reduce inflammation. For severe allergies, allergy shots can desensitize the immune system to cats over time [2].
Immunotherapy
Allergy shots or sublingual (under the tongue) immunotherapy involves receiving increasing doses of cat allergens over time. This can desensitize the body’s immune response. It can take months to years to build up immunity [2].
Managing Allergies
There are several strategies that can help manage cat allergies and allow people to live more comfortably with their feline companions:
Reduce allergen levels in the home. Frequently vacuuming carpets, washing bedding on hot settings, and using HEPA air filters can remove allergens from surfaces and the air. Keeping the cat out of bedrooms can also reduce exposure [1].
Wash the cat weekly. Bathing cats regularly removes dander and saliva from their fur, lowering the amount of allergens they spread around the home [2].
Take medication. Antihistamines, decongestants, and nasal sprays can alleviate allergy symptoms. Allergy shots build resistance over time. Consult a doctor about medication options [3].
Get allergy-friendly cats. Some cat breeds produce lower amounts of Fel d 1 protein, the main cat allergen. Siberian, Russian Blue, and Bengal cats may be better tolerated.
Use air cleaners. HEPA air purifiers efficiently remove allergens from the air. They can provide cleaner air in rooms where the cat spends time.
Keep cats out of bedrooms. Since you spend many hours sleeping in the bedroom, making it a cat-free zone can provide a respite from allergens.
Wear a mask. Wearing an N95 mask when cleaning litter boxes or interacting closely with cats blocks allergens from being inhaled.
Consult an allergist. An allergy specialist can provide personalized advice on managing cat allergies through changes in the home, medications, or immunotherapy.
Cats and Allergies
While any cat can trigger allergies, some cat breeds are marketed as “hypoallergenic” because they shed less dander. Breeds like the Balinese, Russian Blue, Cornish Rex, and Sphynx tend to produce fewer allergens. However, there is no such thing as a truly hypoallergenic cat. Even hairless breeds like the Sphynx produce dander that can cause reactions.
The major cat allergen is a protein called Fel d 1 found in cat saliva, skin and urine. When cats groom, the saliva dries and flakes off into dander. Fel d 1 particles become airborne and are easily inhaled. While no cat is completely non-allergenic, steps can be taken to reduce allergens in the home:
- Bathe your cat weekly to remove dander on the fur
- Vacuum and dust regularly to remove dander from surfaces
- Use a HEPA air purifier to filter allergens
- Wash hands after handling cats to avoid spreading allergens
- Use allergen-reducing sprays and wipes on soft surfaces
- Keep cats out of bedrooms so you have an allergen-free sleep space
While impossible to completely eliminate, controlling exposure to cat allergens can provide symptom relief for allergy sufferers.
Conclusion
In summary, cat allergies are caused by an immune system reaction to proteins found in cat dander, saliva, and urine. While genetics play a role by making some people more prone to allergies, environmental factors are also important. Diagnosis involves testing for IgE antibodies or skin prick testing. Treatments focus on avoiding allergen exposure, medications, and allergy shots. New approaches like vaccines and gene editing cats are being researched to reduce allergens. The future looks promising for better treatments so those with cat allergies can enjoy their feline friends with less reactions.
Going forward, more research is needed into the genetics and specific allergenic proteins involved. Emerging treatments like immunotherapy, modified cat food diets, and potential vaccines will continue to be refined and tested for safety and efficacy. As science better understands the precise immune mechanisms causing allergies, more targeted approaches can be developed. The best outcome will allow people predisposed to cat allergies to still keep cats as beloved pets in their homes.
