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A Guide to Pet Allergies for Animal Lovers

Kelsey Tyler

I recently welcomed a new guy into my bed, and I think I’m in love. Sure, he’s a 10-pound orange tabby, but if you knew how long I’ve waited to share my life with someone like him, you’d understand. 

When I was 14, I developed terrible cat and dog allergies out of the blue. At the time, I had a beloved 7-year-old cat named Pixie. Somehow I muddled through with antihistamines, but they were only semi-effective at relieving my itchy eyes and sneezing, plus they made me feel out of it. After Pixie passed at the ripe old age of 19 (I was 26), I resigned myself to a life in which a fish might be my only option for animal companionship.

Then, about a year ago, in my mid-50s, my allergies disappeared as suddenly as they’d come on decades earlier, allowing Clancy to paw his way into my heart.

According to the Asthma and Allergy Foundation of America, 50 million Americans have experienced allergies of some sort. Almost one-third of them have pet allergies, with cat allergies roughly twice as common as dog allergies. Allergies to pets are thought to be one of the reasons that cats in particular are relinquished to shelters.

“It is very sad when people are allergic to pets,” says Dr. Niha Qamar, an allergist and immunologist at the Allergy, Asthma and Sinus Center of Long Island in New York. “People come in and are pretty heartbroken about it.” Symptoms of pet allergies include sneezing, itchy eyes and wheezing. Cat allergens are especially likely to trigger asthma.

Anecdotal reports suggest that pet allergens can even result in relationship problems. My friend Kelly and her family recently took the plunge after much hesitation and adopted two kittens. Kelly is sometimes allergic to cats, sometimes not. After a week or so with the kittens, all seemed good to go — but then she started to get sniffly. “Honestly, at this point, if we couldn’t keep them, I think my husband would choose them over me,” she says. (Fortunately, her symptoms have subsided.) 

Pet allergies 101

What is it about cats and dogs that can cause these reactions? The culprit is proteins in the animals’ saliva and skin cells (and in the urine of dogs) that collect on the fur and also disperse into the environment. Both cats and dogs produce several different proteins, some of which are more allergenic than others.  

In general, cats are more allergenic than dogs, says Qamar, because the proteins they produce are minuscule — smaller than any other allergen, including pollen and dust mites. The width of a human hair is about 75 microns, while cat allergens are around 6 microns. Dog allergens, she estimates, are about twice as big. Since cat allergens are so tiny, they seem to enter the respiratory tract easily.

They also get on everything. “Cat dander sticks to walls, blinds and air vents,” says Melanie Carver, chief mission officer at the AAFA. “After removing a cat from an environment, it takes six months for cat dander protein levels to dissipate.”

Also, sorry, but there is no such thing as a hypoallergenic dog or cat, whether it has fur, hair or neither. “Big dog, little dog, short hair, long hair — all dogs produce allergens,” says Dr. James Wedner, director of the Asthma and Allergy Center at the Washington University School of Medicine in St. Louis. The same is true with cats, he says. “Even the [hairless] Sphynx cat is very highly allergenic.” The reason for this is that hairless cats groom themselves just like furry cats do, leaving a sticky residue of saliva on their skin.

Research bears this out. For one 2011 study, researchers collected dust samples from the floors of 173 homes that had one dog each. The study involved 60 dog breeds, 11 of which are often labeled hypoallergenic. The dust samples were analyzed for the most common canine protein and found that the levels of the allergen were no different in homes with so-called hypoallergenic dogs. 

But while hypoallergenic breeds are not a thing, it is possible to be more or less allergic to an individual cat or dog of any breed. “It’s like a puzzle piece,” says Qamar. “It’s the person and it’s the dog [or cat]. You can be sensitive to one particular protein, but that [specific] animal might have a lot less of that protein.”

Qamar urges anyone who wants a pet and is prone to allergies to spend some time with it before committing. “I tell people just to be very aggressive about it and really get in there and be all over the dog, put your face in the dog, you know, and if you have no symptoms, like feeling congested or sneezy or itchy, that’s the way that you figure out if this dog is right for you.”

Treatment options

It turns out that losing allergies to pets over time is not that unusual. People can outgrow allergies as the immune system ages. With this phenomenon, called immune system senescence, the immune system essentially becomes less reactive to allergens. But you can’t wait for that to happen when you’re already living with an animal. 

Assuming you’re not going to avoid having pets altogether — which some might say is the most sensible approach — your anti-allergy arsenal for symptom management includes over-the-counter antihistamines and home remedies, such as keeping rugs and heavy drapes to a minimum (they collect allergens), vacuuming regularly with a vacuum that contains a HEPA filter and running a freestanding HEPA filter in your home. One of the most important things, says Wedner, is to designate your bedroom a pet-free zone. “But people don’t do what you tell them,” he says. “They say they love sleeping with their pets.”

Washing a dog regularly is a feasible way to reduce allergens; washing a cat, not so much, since many cats hate water. In a study, Wedner and his colleagues did find that washing cats helps cut down on allergens. “What we forgot to tell people is that we put the cats to sleep [i.e., we temporarily sedated them] when we washed them. You can’t throw a cat in a tub of water.”

The gold standard for curative treatments remains subcutaneous immunotherapy, informally known as allergy shots. Injections are given in a doctor’s office over the course of several months. They contain small amounts of the allergen, causing the patient to develop immunity to it over time. Qamar estimates that for her patients with moderate to severe allergies, the success rate for shots is around 80 percent for dog allergies and 85 to 90 percent for cat allergies.

Intriguingly, there’s also now a way to actually alter the amount of the main allergen found in cat saliva. 

Wedner was involved in a study funded by Purina which discovered that a protein found in chicken eggs neutralized the most common cat allergen, called Fel d1. After the cats were fed the food for three weeks, the amount of the allergen they produced decreased by 47 percent. As a result, Purina created a dry cat food that contains the chicken protein.

“We view it not as a complete treatment, but as an adjunct,” says Wedner (who isn’t affiliated with Purina), based on the initial feedback from people who are using the food. “Some people are all better, some are somewhat better, some not at all.”

The upshot is that there is no one-size-fits-all approach for managing pet allergies. Some may find relief with one treatment, while others need a multicomponent approach.

Deborah Marcus, 50, currently has two cats, thanks to shots. Like me, she grew up with pets and developed allergies in her 20s. “It became very difficult to breathe,” she says. She tried shots, but they caused unpleasant side effects.

Three years ago, she gave the shots another try. After a year of a twice-weekly protocol, followed by six months of a maintenance dose, she was ready for cat ownership. “I have my two babies now and I have no problems,” she says. “They sit on me and sleep with me. I’m actually covered in cat hair right now.” 


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The Paper Gown, a Zocdoc-powered blog, strives to tell stories that help patients feel informed, empowered and understood. Views and opinions expressed on The Paper Gown do not necessarily reflect those of Zocdoc, Inc.

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