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Are You Allergic to Cats But Not Allergic to Dogs?

Being bipetual (owning cats as well as dogs) can be difficult when you're allergic to one species but not the other. Let's look at pet allergies.

Melvin Pena  |  Jan 26th 2016


When people find out that I write for Catster and that I am allergic to cats, one standard response is, “That’s ironic.” It’s unfortunate that I cannot handle a cat without having to thoroughly wash my hands immediately afterward. It’s inconvenient that I have to wash my coat after visiting the homes of friends who own cats. Having a cat allergy sucks, and I have to be more circumspect about how I interact with cats, but there’s no irony in it. If we must apply vague literary terminology to it, it’s more of a tragedy that I love cats but cannot interact with them without suffering.

Mine was a late-onset allergy. Since around age 5, my family continuously owned both cats and dogs. It wasn’t until college, when I was spending much more of the year away from home and out of the continual presence of cats, that my cat allergy began to manifest itself. Stranger yet, I found that, while even limited interactions with cats would provoke allergic reactions, the phenomenon did not extend to dogs. Let’s examine pet allergies and see why people like me might be allergic to cats, but not dogs. Questions we’ll cover:

  • Do cats or dogs cause more allergic reactions?
  • Why are some people allergic to cats but not dogs?
  • Can cat allergies develop during adulthood?
  • Are there non-allergenic cats or dogs?
  • Do cats and dogs have allergies to each other?
allergic to cats but not dogs

It’s tough being bipetual when you’re allergic to cats but not to dogs. (Photo by Nguyen Hoangnam on Flickr)

Do cats or dogs cause more allergic reactions?

According to the Asthma and Allergy Foundation of America, nearly a third of all Americans are allergic to cats or dogs, and among them, there are twice as many people who are allergic to cats than dogs. The results of an 18-year study presented at the American College of Allergy, Asthma, and Immunology’s national meeting in 2013 showed that people with asthma who were diagnosed with cat allergies had more than doubled during that period.

Cat allergies have little or nothing to do with the length or density of a cat’s coat, and everything to do with proteins found in cat dander, saliva, and urine. Several such proteins exist, but the ones most responsible for provoking cat-related allergies are Fel d 1 and Fel d 4. The first is a protein naturally occurring in a cat’s skin and produced by a cat’s sebaceous glands, which create the oils that coat a cat’s fur and skin. The second is a protein found in a cat’s saliva.

Why are some people allergic to cats but not dogs?

The biggest culprit for cat allergy sufferers is dander, or dead skin cells that are sloughed off over time and in the course of cat self-grooming. Dogs produce dander as well, so why are more people allergic to cats than dogs? The two proteins most culpable for dog-related allergies are called Can f 1 and Can f 2. Each of these dog allergens is concentrated in the dog’s saliva rather than skin cells.

I have also encountered a theory in my research that allergens produced by cats, particularly the Fel d 1 found in the skin and its oils, are more adhesive and remain airborne longer than those found in dogs. Whether this hypothesis is valid, the most substantive difference between dog and cat allergens may be one of chemical composition. It may also be the combination of skin and saliva in cats compared to the primarily saliva-borne allergens in dogs.

allergic to cats but not dogs

There is no breed or mix of dog or cat that is universally or reliably free of pet dander. (Photo via torange.us)

Can cat allergies develop during adulthood?

Yes! Adult-onset allergies do occur. The reasons why people who have never experienced allergic reactions to dogs or cats and suddenly seem to be affected by them are unknown. Since allergies to pet dander are related to an over-reactive immune system, late-onset allergies may be related to aging, increased exposure, or environmental changes. As cats and dogs themselves age, they produce an increasing volume of dander, so the cause might be on the human’s side or the pet’s.

There is also the phenomenon I experienced when I visited home during breaks from school, which is colloquially known as the Thanksgiving Effect. In this scenario, people who have lived their entire lives around pets and move away for an extended period of time, return to find themselves affected by allergens that did not affect them before. The idea is that prolonged early-life exposure to pet dander builds up a tolerance to it. Sudden, concentrated reintroduction to the allergens then provokes an extreme response from the immune system.

Are there non-allergenic cats or dogs?

Some people use the term “hypoallergenic” to mean “non-allergenic” or “allergy-free.” While the creation and development of so-called hairless cats or designer dogs may have been influenced by a desire to limit exposure to pet hair, shed fur is not the cause of allergies. Pet hair can retain dander, but as an airborne particulate, it’s also regularly found even in places where there are no pets. Cat and dog dander travels freely and can be conveyed into any environment on any surface, including clothing.

All cats have skin and saliva, and all cats produce dander. Dogs who shed less may leave less hair around the home, but their saliva still contains the proteins that cause allergies. There are no cat or dog breeds that are universally or dependably allergen-free. If there are dogs or cats who are suitable for people with allergies, they can only be found by trial and error and determined on a case-by-case basis, not by breeding.

allergic to cats but not dogs

How do self-professed cat people manage cat allergies? (Photo via Shutterstock)

Do cats and dogs have allergies to each other? To humans?

Cats and dogs do have allergies. They can experience allergic reactions to food, household chemicals, and plants, among other things. While a dog who is allergic to cats or a cat who is allergic to dogs is rarely diagnosed, it is entirely possible. Humans shed skin cells and produce dander as well, so yes, it is also conceivable for a particularly sensitive cat or dog to be allergic to people.

Are you allergic to cats but not dogs? How do you cope?

There are countless ways to handle cat and dog allergies when your exposure to them is time-limited. Many of my friends have cats, which I can tolerate without allergic reactions for a few hours at a time if I simply don’t touch them, or wash thoroughly when I must. When I experienced the Thanksgiving Effect with my family’s cat, she had to become an outdoor cat. Until the end of her life at age 17, I coped by either having most of our our physical interactions mediated by a hairbrush or observing strict hygiene routines.

These may not be viable or acceptable options for a lot of people, of course, and it can be wrenching to have to put a beloved pet up for adoption or fostering. Other alternatives include allergy shot regimens, special air filtration systems, and rigorous cleaning habits. Have you found yourself in a situation where you’ve become allergic to cats but not to dogs? What strategies did you find successfully allowed you to keep a pet and manage an allergy?

About the author: Melvin Peña trained as a scholar and teacher of 18th-century British literature before turning his research and writing skills to puppies and kittens. He enjoys making art, hiking, and concert-going, as well as dazzling crowds with operatic karaoke performances. His 17-year-old cat recently passed, he has a two-year-old female Bluetick Coonhound mix named Baby, and his online life is conveniently encapsulated here.