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Coughing, wheezing, red eyes, stuffy nose, hives, and sneezing. Those are some of the symptoms that I and about 10% of the U.S. population with pet allergies experience. And the most common offenders are our domesticated feline friends. However, contrary to what you might think, it’s not cat hair coat or fur itself that’s the issue. People with cat allergies actually react to allergen proteins found in cat urine, saliva, hair, and dander—dried flakes of skin.
Unfortunately, the current standard of care is to treat the cacophony of flu-like symptoms or to avoid the animal. Consequently, the latter is the main cause of cat abandonment and genesis of invasive feral cat populations.
Now, two different teams of researchers successfully have made advancements towards preventing cat allergies. A group of researchers has created cat food with antibodies—immune molecules that recognize and neutralize foreign particles—targeting a key cat allergen. Another group produced an allergy vaccine for cats. In both cases, the researchers saw allergen reduction in the cats tested.
Not only does this mean that cat lovers with allergies may soon be able to snuggle up to their favorite Felis catus throughout the day and night, but it also can play a major role in curbing feral cat populations in the future.
According to a 2017-2018 survey in the United States, about 85 million families reported owning pets nationwide. Strikingly, that’s almost 2 out of 3 American households! This survey also found that 47 million households owned at least one cat and that there are about 94 million cats in the US. This is somewhat problematic to the roughly 1 in 10 people in the U.S. with pet allergies. And amongst the most common culprits are cats.
Cats make a variety of potential allergens. In particular, there is one allergen—Fel d1—considered to be the main cat allergen. This allergen is found in cat saliva as well as the oil produced by their sebaceous glands. As cats groom, Fel d1 is distributed within the hair coat and shed with the cat hair and dander.
This allergen can annoyingly be airborne for long stretches of time making it an incredibly easy allergen to breathe in. Fel d1’s structure helps it stick to carpet, fabrics, and upholstered furniture. For these reasons, it is difficult to remove from the home and can travel on clothes and other items (e.g. backpacks, purses). This even allows the cat allergen to spread to households that don’t own a cat. On top, the more cats in a community, the more allergens found in people’s homes even if they didn’t own a cat.
A pawssible cure for cat allergies?
The role of the immune system is to seek and destroy foreign substances, like bacteria and viruses. Usually, immune responses protect us from diseases. But sometimes our immune systems react abnormally to a foreign substance—an allergic reaction. These allergy-causing particles are known as allergens.
People with pet allergies have immune systems that are too sensitive, reacting to harmless molecules produced by pets. The resulting symptoms are what constitutes an allergic reaction—stuffy nose, inflamed eyes, swelling, itching, coughing, and wheezing.
Usually, allergies are treated with allergy shots. It has been used to treat allergic reactions to grass pollens, house dust mites, and bee venom. An allergy shot consists of small amounts of the allergen that you’re allergic to. This trains you and your immune system to become less allergic to the substance. Your immune system learns to make neutralizing antibodies so that you don’t react the next time you run into the allergen.
More recently, researchers have started making the neutralizing antibodies in a lab to give directly to patients. This approach to treating patients using antibodies is also being used for new cancer treatments.
Interestingly, chickens—and other birds, reptiles, and amphibians—naturally make antibodies that get passed on to their offspring via the egg yolk. As a result, tons of antibodies accumulate in chicken eggs to pass on immunity to offspring. Researchers have been able to hijack this process to deliver lab-made antibodies in food. This process has been used to treat diarrhea in domestic animals.
And I’m feline good
Researchers used this process to treat cat allergies by reducing the cat allergen Fel d1. To do so, they first collected cat hair from 105 for two weeks on their normal diets. Then, they fed the cats food with Fel d1 antibody for 10 weeks, collecting hair along the way. Finally, the researchers compared the presence of Fel d1 in samples before and after switching to antibody-supplemented food.
When looking at hair taken from cats fed food with a Fel d1 antibody, a vast majority of the cats showed a major reduction in the allergen. Plus, about half the cats showed that the level of Fel d1 dropped by more than half, and cats with the highest initial levels showed the greatest decrease. This means that feeding antibody targeting Fel d1 cats successfully reduced the amount of allergen on their hair coat.
But, is supplementing cats with antibodies the best way to neutralize the allergens? What if there were a way to get cats to make the antibodies themselves, like a cat allergy vaccine? Theoretically, this would block the allergic response at the first possible point of intervention. These antibodies will bind the allergen made by the cats and, therefore, decrease or neutralize its allergenic effect in human subjects.
To test this, a company called HypoPet developed a new strategy to immunize cats against their own major allergen, Fel d1. Their vaccine called HypoCat was well tolerated by cats and had no overt toxic effect. All cats induced a strong and sustained specific antibody response. The induced antibodies strongly bound and neutralized the allergen Fel d1. They observed a reduction in the level of allergen made and secreted by the cats. This means that using this vaccine on cats might result in reduced symptoms of allergic cat owners.
The purrr-fect solution
Cat allergies, besides causing discomfort, can lead to chronic diseases including asthma. Until a solution hits the market, we will continue to be without effective treatment for cat allergy in humans. So, these cat allergy treatments may have major health and financial consequences. In fact, they may even broader consequences.
For example, the current prescribed course usually consists of treating the symptoms and avoiding the animals. In many cases, this leads to separation between owners and their cats, traumatic for both animal and human. Yet, the number one cause of cat abandonment is allergy experienced by owners and the people in their lives. Sadly, of the 3.4 million cats abandoned annually to U.S cat shelters, more than a third (approximately 1.4 million) of these animals are euthanized.
And it doesn’t stop there. Cat allergy is also a leading reason for the abandonment of the animals into urban and native environments. Not only do these abandoned animals suffer, but ecosystems can potentially become disrupted by the introduction of an unnatural, new player—the feral cat. Devastating to wildlife, feral cats are one of the worst invasive species on the planet. So, beyond nourishing the timeless and loving bond between humans and their feline companions, treating cat allergies can also help promote native wildlife abundance and diversity.