A company in the USA has been working for several years to develop a ‘hypoallergenic cat' – in other words a cat that is safe for those people who are allergic to cats, and one that will not trigger the usual allergic reaction.

Humans with cat allergies

Allergy to cats is relatively common among humans, but in most cases it is part of a combined allergy (ie, individuals are allergic to a number of different things, with cats being only one of them). The most commonly implicated source of cat allergies is a glycoprotein called ‘Fel d1' – this is found in the skin, sebaceous glands (oil glands in the skin), saliva and elsewhere. The widespread distribution of Fel d1 on the skin (through local production and through grooming and spread via saliva) results in significant contamination of the environment in which cats live. While this is not normally a problem, to those individuals who have developed a cat allergy, this exposure can result in the development of clinical signs.

Although Fel d1 is recognised as the major antigen (protein) responsible for cat allergies in humans, there is evidence that other proteins (eg, Fel d4) may also play a role in some individuals.

The hypoallergenic cat

A company called Allerca Inc ( www.allerca.com ) based in San Diego in the USA have been developing a ‘hypoallegenic' cat for a number of years and reports suggest that the first such cats will be available to buyers in 2007. The company have been attempting to produce cats that do not produce the Fel d1 antigen, and thus may avoid triggering a response in humans that are allergic to other cats.

According to information that has been produced on their web site, Allerca have identified that some cats produce variants of the Fel d1 glycoprotein that are sufficiently different from the usual Fel d1 that it does not produce the allergic response in exposed humans – these cats have a different gene in their DNA encoding a different form of the glycoprotein. The company appears to have identified a number of cats producing variants forms of Fel d1 and then used a controlled breeding program to produce a source of cats with the different variant of Fel d1 which are thus considered ‘hypoallergenic'.

It appears that the approach taken by the company would be analogous to identifying certain preferred traits among pedigree cats and breeding specifically for these traits, or indeed similar to the techniques used to produce ‘new breeds' of cats by selectively breeding between different breeds. As such, these cats do not appear to be ‘genetically modified' rather than ‘selectively bred'.

Whether the promise of the ‘hypoallergenic cat' meets hopes and expectations remains to be seen, but there is a genuine possibility that this could be a solution for cat enthusiasts that find difficulty in living with a cat due to severe allergic signs.

However, confirmation that this technique is effective will rely on independent investigations that will undoubtedly be done in due course. Even if these cats do successfully avoid triggering the typical allergic response to Fel d1 in sensitive individuals, the existence of other potential allergens (eg, Fel d4) may mean that clinical signs are not avoided in all allergic individuals, although further work will be needed to know if this is an important issue.

One other potential area of concern might be the size of the gene pool used during the selective breeding programme to develop these cats. Just as we have seen certain inherited problems arise in pedigree cats through selective breeding using a very limited gene pool, the same could also potentially occur with these cats. However, details of the breeding programme and numbers of cats used have not been released and any potential risks are currently unknown.

Allergen avoidance and controlling pet allergies

Although acquiring a cat that doesn't trigger an allergic reaction may potentially be the best solution to avoid allergic reactions in sensitive individuals, this is unlikely to be a practical solution for most people.

With severe cat allergies, the only solution may be to avoid having a cat in the house at all. For most people though, a combination of different strategies to try to reduce the amount of Fel d1 antigen in the environment will help to successfully control the clinical signs of cat allergy to an acceptable level. In addition to these recommendation though, medical advice should always be sought if you suspect that either you or one of your family is suffering from allergy to cats.

Some common simple recommendation to help manage cat allergies:

Remember too, that for most individuals with cat allergy, the cat is only one of a number of different allergies and it is important to minimise exposure to other allergens also.

 

 

June 2006