HELP! I’M ALLERGIC TO THE CAT
1996 - 2007 S Hartwell

This was originally written as a pamphlet for a cat shelter which was regularly presented with cats unwanted due to "allergy". Doctors in the area were over-diagnosing cat-allergy, leading to many cats being unnecessarily relinquished. This was aimed at potential adopters. There are plenty of websites specifically about living and coping with cat-allergy.

Cats are reckoned to be one of the most allergenic creatures kept as pets. They can carry allergens (substances which can trigger an allergic reaction) which can trigger:

• hayfever-like symptoms
• asthma attacks in asthma sufferers
• cat-scratch fever (cat scratch disease)

Although the term "hypoallergenic" means "reduced allergens", many people misunderstand it to mean "allergen-free". This leaflet deals with the commonest type of allergy: red, itchy eyes, runny nose, sneezing and breathing problems. In 2003, a report came out suggesting that dogs, not cats, were more likely to cause allergies in humans.

If the only option is to rehome your cat, please remember that rescue shelters often have long waiting lists and might not be able to take your cat immediately. because so many cats are unwanted for very trivial reasons, some rescue shelters may require a doctor’s certificate as proof of your allergy. Doctors which are anti-pet or anti-cat are more likely to say "get rid of the cat", though the real cause may later be shown to be house-mites, pollen or chemicals in the environment. By then, it will be to late to retrieve the cat from a shelter or its new home or, worse, it may have been destroyed.

WHAT CAUSES CAT-ALLERGY?

Older books on cats and cat care usually blame the allergy on cat fur e.g. breathing in small particles of the fur itself. Some blame it specifically on the cat’s guard hairs (the long hairs in the cat’s coat) and may recommend keeping a breed which lacks these guard hairs e.g. Devon/Cornish Rex or the hairless Sphynx. Referring to these breeds as hypoallergenic or allergen-free is incorrect as It is not the hair which causes the allergic reaction.

The real culprit appears to be cat saliva which contains an allergen; this allergen is a protein called Fel d 1. When a cat washes itself, saliva is deposited on its fur (or skin in the case of hairless cats). The saliva dries into dust (dander or dandruff) which is released when a cat scratches or moves and when humans stroke or brush a cat.

All cats wash, even those which lack guard hairs or which lack hair altogether. The dust forms on all types of cat hair or directly on the cat’s skin if it lacks fur. Hairless Sphynx cats produce dandruff directly on their skin and though they produce less of it than furred cats, they can still produce enough to trigger an allergic reaction. An allergy occurs when the body over-reacts to a substance (allergen) and produces excessive amounts of histamine. Excessive histamine production leads to the irritating symptoms associated with cat-allergy - itchy eyes, sneezing, skin rash etc.

Although Fel d 1 is the protein most often associated with allergies, humans are very variable and there will be some people who develop allergies to other feline proteins. I have met people who are unaffected by Siamese cats, but allergic to other cats and I have a friend whose cat alergy is only triggered by male cats (even if the cats are neutered).

In general, it is not the cat hair which causes the allergy, it is the dandruff (dust) on the cat’s hair and skin. All cats produce dandruff, though some cats produce less than others. No cat is allergen-free, not even hairless cats.

IS THE CAT TO BLAME?

People are quick to blame an allergy on their cat even if they haven’t suffered previously. Doctors too find the cat a convenient scapegoat. Many people rehome or euthanase the cat, only to find that they are allergic to house-dust mites, furniture polish or dust from a new carpet.

To avoid unnecessary guilt, check that the cat is the source of the allergen. It is possible to have a skin test to see whether the cat Is the cause of the allergy. Some sufferers are successfully treated for cat-allergy by desensitising injections.

• Is it an allergy? Colds and infections can cause similar symptoms to a cat allergy.
• Ask your doctor to do an allergy test to confirm that the cat Is to blame. The cat may be completely Innocent!
• Does the allergy go away when you are in a cat-free area?
• is the allergy seasonal? Could it be caused by environmental factors such as a certain type of pollen? Does it only occur during the cat’s seasonal moults?
• If the cat is boarded at a cattery for two weeks, are symptoms reduced? This is only a rough guide since it can take two or three months to get rid of residual allergens in the house e.g. dust in carpets and furnishings.

In one British survey in the 1990s, 100 asthma sufferers were questioned. Only 10 thought their condition was animal allergy and only 4 thought it was cat allergy.

CAN I REDUCE THE ALLERGIC REACTION WITHOUT REHOMING THE CAT?

Many owners tolerate mild allergies. Those whose symptoms worsen during moulting seasons find that antihistamine tablets, nasal sprays or homeopathic remedies can help during these seasons. There are measures you can take to reduce the problem of an allergy.

• Inquire about desensitising treatment. Not all GPs offer this treatment.
• Use a spray which can be applied to the cat’s fur to neutralize or reduce allergens on its fur. The apparent “effectiveness” of these sprays varies as some people are more allergic than others.
• Wear a pollen filter mask whenever you groom the cat or indulge in long cuddles with it. Grooming is best done in a well-ventilated area so that the dust dissipates.
• Restrict the cat’s access to certain rooms. Some rooms should be kept cat-free. Don’t let the cat sleep in your bedroom as it will leave behind dust-coated fur.
• Invest in a good air filter unit. These are not cheap, but they extract the minute dandruff particles which pass through most vacuum cleaners.
• If the cat lives indoors only, bathe it in distilled water each month to wash away dried saliva dust. Tap water leaves residues on the cat’s fur.

I'D LIKE A CAT BUT I THINK I MIGHT BE ALLERGIC

Though some books may claims that Rex and Sphynx cats don’t cause allergies this claim should be taken with a pinch of salt. The majority of cat allergies are caused by the dandruff (dried saliva), not the fur itself so any cat can trigger a reaction regardless of whether it has fur.

• Spend time with friends’ cats (or even at a cat shelter) to see if you react. Most allergies develop after more than one exposure to a potential allergen, so spend plenty of time handling the cats until you are quite sure you are not allergic to them.
• Ask your doctor for an allergy test.
• If you know you are usually allergic to cats, but intend to get one of the supposedly hypoallergenic breeds, spend time with cats of that breed as they may still produce enough allergens to trigger an adverse reaction.
• Agree with the cat shelter or breeder that the cat can be returned to them if you suffer a genuine reaction. You may have to get a doctor’s certificate as proof that you really do have an allergy and you haven’t simply changed your mind about having a cat.
• Minimize allergic reactions by following the simple guidelines above.

If you can spend only a few hours with a cat before suffering discomfort, or you need to take anti-histamines when visiting cat-owning friends, it is best not to acquire a cat.

• “Time-share” a friend’s cat, perhaps by cat-sitting it for short periods of time or feeding it when they are on holiday. You could take antihistamines whenever you visit the cat.
• Sponsor an unhomeable cat at a cat shelter. You contribute towards its upkeep and can usually visit the cat, even if it can’t be handled.
• You may be in an area suitable for a feral outdoor cat. It will require food and shelter (in a shed etc), but won’t want to live in the house with you or be cuddled. Many British (and some American) cat shelters are looking for homes for outdoor cats as farm cats (barn cats).

If you suffer from asthma, seek a doctor’s opinion before taking on a cat. It may save heartbreak later on. If you use your inhaler as directed by your GP (physician) (usually first thing in the morning and at regular intervals during the day rather than when you actually suffer an attack) you may be able to avoid adverse reactions to your cat.

CAT-ALLERGY LEAGUE TABLE

For most cat-allergy sufferers, it is not the cat hair itself which causes the allergy, it is the dandruff (dust) on the cat’s hair and skin. All cats produce dandruff, though some produce less than others. No cat is allergen-free, not even hairless cats.

The amount of allergen on a cat’s coat depends on its fur length and possibly fur type. Some people may be allergic to large quantities of the allergen (e.g. on longhaired cats), but suffer fewer problems with cats that have lower levels of dandruff because they have less fur to carry the dust. No cat is truly hypoallergenic for everyone - it all depends on how badly allergic you are.

LONGHAIRED CATS

Long fur needs more washing which means more saliva gets deposited on the coat where it dries to form allergenic dandruff. The longer fur also means a greater area on which dandruff can form. Longhaired cats need regular brushing and this releases large amounts of dust from their fur. Fluffy fur is almost irresistible, but stroking it releases large amounts of dust.

Interestingly, it is sometimes claimed that the Siberian Cat (a longhair) is hypoallergenic and produces less of the Fel d 1 allergen than other cats. This has not been verified in all lines of Siberian or in all cat allergy sufferers. The best advice is to spend time with the cats before acquiring one to test out their supposed hypoallergenic condition. Some people are allergic to other feline proteins that are found in the cat's saliva and dandruff and these people will be just as allergic to Siberians as they are to any other breed.

SHORTHAIRED CATS

The shorter fur means less surface area on which saliva is deposited, but this still creates enough dandruff to trigger allergic reactions In many sufferers. Monthly bathing in distilled water can reduce allergens to a tolerable level In indoor-only cats.

Some allergy sufferers report they suffer less reaction to Siamese and Burmese (i.e. the European Burmese) than to other shorthairs. This was originally believed to be due to those cats have a different hair structure. It may be that some of these strains of cats are genetically different enough that they produce less of the allergen. There is no evidence that they are hypoallergenic for everyone.

REX-COATED CATS

The crimped, short fur and sometimes sparse coat means less surface area on which dandruff can form, but it may still be enough to trigger an allergic reaction in many sufferers. Don’t be fooled into believing these cats are hypoallergenic - it depends on how much of the allergen it takes to trigger a reaction in the individual. Once again, washing in distilled water may reduce the levels of allergen.

HAIRLESS CATS

Even though it lacks fur, this type of cat still washes and saliva is deposited directly onto its skin where it dries to form dandruff, especially in wrinkled areas. Since cat-allergy Is usually due to the dandruff and not the fur itself, absence of fur does not automatically mean absence of the allergen. Hairless cats may need to be sponged regularly to remove the dandruff.

"THE ALLERGY-FREE EGYPTIAN HAIRLESS CAT"

There is no such breed. This cat was an invention of the TV series "Friends". Unfortunately, it has led many people - and even some doctors and veterinarians - to recommend this breed as a pet for cat-allergy sufferers. Many people have wasted uncountable hours trying to find an Egyptian Hairless Cat before they discover these don't exist. It was irresponsible of the TV series writers to mislead people and perpetuate the myth that hairless cats don't cause allergies. They have caused many people to waste a lot of time.

GENETICALLY MODIFIED ALLERGEN-FREE CATS

Researchers believe it could soon be possible to "knock out" the gene which causes the allergy-causing protein and to breed allergy-free cats in the future. There is the danger that the gene plays a crucial role in some other part of the cat's metabolism so that removing it could cause disease in the cat e.g. affect its immune system. In some laboratory animals, knocking out genes has had the side effect of promoting cancers. It will be some years before researchers know whether it is safe to produce allergen-free cats. They will also be expensive as demand is likely to outstrip supply. In addition, there are moral and ethical objections to breeding - and destroying - hundreds of undesirable and unwanted allergen-bearing kittens (in a world where hundreds, if not thousands, are already destroyed daily) while trying to perfect an allergen-free strain. It is classed by many cat lovers as animal research because of the risk to the cats. Any cross-breeding of allergen-free cats would be likely to restore the gene, undoing the genetic modification.

In April 2005, scientists at the University of California created a human-cat chimera (i.e. mix of genetic material from both species). They fused the feline Fel d 1 protein (the protein that triggers the allergic reaction in cat allergy sufferers) with a human protein known to suppress allergic reactions. When tested in mice, the chimeric protein stifled cat allergy. The feline part of the protein binds to the specific immune cells that generate the allergic reaction to Fel d 1. Thehuman part of the protein also binds to the immune cells and tells them to stop reacting. Because the human part is more dominant, the allergic reaction is halted. Chimeric proteins could be used to desensitise allergy sufferers by retraining their immune system. This offers an alternative to GM cats.

Felix Pets (part of Transgenic Pets) are attempting to produce genetically modified "knockout cats" in which the gene producing the allergen is removed or switched off. They hope tp have non-allergenic cats in 2008. No-one yet knows what side-effects (possibly adverse) this could have on cats, Duane Kraemer (professor of veterinary physiology and pharmacology, Texas A&M University in College Station) the owner of cloned cat "CC" says the only way to find out is to create knockout cats in the lab and see how they manage without a Fel d1 gene or protein.

SELECTIVE BREEDING PRODUCES HYPOALLERGENIC CAT (SEPT 2006)

In September 2006, the world's first selectively bred "hypoallergenic" kittens were born in the USA. American biotechnology firm Allerca claims to have created hypoallergenic kittens by reducing the amount of the Fel d1 glycoprotein (the main allergen for those with cat allergies) they secrete in their saliva. For most cat-allergic people, these cats will not cause red eyes, sneezing or asthma, although people with severe allergies may still react to the reduced amount of Fel d1. An estimated one third of humans suffer from allergies.

Allerca claim to have selectively bred cats that produce a modified Fel d1 protein less likely to cause allergies. Though they charge a high price for supposedly "hypoallergenic cats" (and aim to set up a franchise operation) they have not published any research data for peer review nor permitted independent verification of the claims (Asheras and Allercas). Until the work is independently reviewed and verified, their claims should be treated with suspicion, particularly in the light of the company founder's previous convictions for fraud.

At $3,950 (£2,104) each, the three kittens have already been reserved and there is a waiting list. Allerca started taking orders for hypoallergenic cats in 2004. Unlike some proposals for hypoallergenic cats, Allerca did not use genetic modification. They tested huge numbers of cats looking for those few (approximately 1 in 50,000 cats) that lacked the glycoprotein Fel d1. The cats lacking the allergen were then selectively bred. This method was time consuming but natural and avoided genetic modification. Knocking out the gene(s) that produced Fel d1 could have had damaging side-effects as the gene may be involved in other functions. Using an existing mutation is the same method by which breeds of livestock breeds have been developed by humans.

There could also be a global market for the cats and it is claimed that they will not deprive other cats (e.g. in rescue shelters) of homes since those who will buy them would not have bought or adopted an non-hypoallergnic cat. It is possible that the kittens will be neutered before being released to new homes to prevent the "backyard breeding" of hypoallergenic cats by those wanting to cash in on the development.

Cat Scratch Fever (called Cat Scratch Disease in the USA) is caused by the bacteria Bartonella henselae carried by around a third of cats. Despite its common British name, it rarely causes fever. It causes systemic illness and lymph node lesions. In healthy humans, the disease is usually a minor infection which clears by itself. It is usually diagnosed too late for any action to be taken (i.e. the body already has it under control by the time a doctor takes samples). It is more serious in people with poor immune systems.

Antibiotics usually cure the disease without complications in healthy young adults. The bacteria must also be cleared from the cats - this requires long term antibiotic treatment and cats can be reinfected by infected fleas. Similar symptoms can also be caused by related bacteria in other mammals; in about 10% of reported cases, the sufferer has not had contact with cats.