Allergic to a Dog But Not a Cat

Many people are under the mistaken impression that pet allergies are caused by pet hair. They believe that breathing in this pet hair is what triggers an allergic reaction. In actuality, pet hair doesn’t cause allergic reactions. Instead, pet dander — the dead skin flakes that naturally fall off the pet’s coat — are the cause. With that in mind, is it possible to be allergic to a dog but not a cat?

The short answer is: Yes. Even though both allergies are triggered by pet dander, the chemical composition of the proteins causing the allergy is different.

How Pet Allergies Work

Having an allergy means having an overactive immune system. When your immune system comes into contact with the allergen, it releases a flood of histamines. These histamines then release chemicals meant to fight the “invader.” The combination of histamines and chemicals is what causes traditional allergy reactions like nasal congestion, respiratory issues, and skin irritation.

With pet allergies, the immune system reacts to specific proteins found in pet dander. The proteins are different for cats and dogs. This means that the immune system may react to a dog’s protein, but not a cat’s.

It’s more common for people to be allergic to cats without being allergic to dogs. Part of this is because cat allergens are found in a cat’s sebaceous glands, so they coat the fur and skin of the feline. The most common dog allergens, by comparison, are only found in dog saliva. As such, they’re less likely to come into contact with your body.

With that said, it’s not unheard-of for people to be allergic to dogs and not cats. If your immune system doesn’t react to cat proteins but does react to dog proteins, you might experience allergic reactions around dogs even if you’ve never had a problem with cats.

The Effects of Exposure

Studies indicate that being exposed to animals over a period of time decreases the chances of allergic reactions. It also decreases the severity of reactions if a person already has an allergy.

One example is with infants. Research indicates that having a cat or dog around an infant can lessen their chances of developing allergies in the future. However, if the child is predisposed to allergies, this type of exposure therapy might not work.

Exposure therapy has also been shown to lessen allergy symptoms in adults. Adults who live with an animal they’re allergic to find that their allergy symptoms lessen over time. There are precautions and steps you can take to lessen the amount of allergen released into your environment.

This means that if you’ve lived with cats your entire life, you have a lower chance of developing a cat allergy than a person who has never lived with cats. Similarly, if you’ve always lived with dogs, your chances of developing a dog allergy lessen.

Many people who are allergic to dogs and not cats are people who have lived with cats for their entire lives. It’s possible that their exposure to the cats is what prevented them from developing an allergy. Because they weren’t exposed to dogs, their immune systems were more likely to identify dog dander as an invading pathogen.

Exposure isn’t a hard and fast rule, though. Just because a person has been exposed to an allergen doesn’t mean they’re guaranteed not to develop an allergy. Some people with both dogs and cats will develop allergies to one or both animals. Meanwhile, some people who have never had dogs or cats will never have an allergic reaction to either animal.

The Role Genetics Plays

Genetics plays a role in the development of allergies. A person’s immune system and immune responses are governed almost entirely by genetics. If a person’s parents are predisposed to any kind of allergies, that person has a much higher chance of having an overactive immune system.

Allergies themselves can sometimes be passed down from parent to child. If a parent is allergic to cats, their child might then be allergic to cats. However, allergies seem to develop in response to the individual’s environment. This means that a parent with a pollen allergy might have a child who’s fine around pollen, but who has a dog allergy. The presence of allergies matters more than what exactly the parents are allergic to.

Testing for Allergies

Allergy testing is typically done with either a skin prick test or a blood test. Skin prick tests are most commonly used.

With a skin prick test, your doctor will introduce a small amount of allergen to your skin through a small pinprick. All you have to do is wait for about fifteen or twenty minutes to see whether an allergic reaction occurs. Doctors may do several skin prick tests at once to test multiple allergens.

Blood tests are an ideal testing agent for people who can’t tolerate multiple skin pricks. Just one sample can test for up to ten different allergens by identifying antibodies in the blood. In addition, blood tests are helpful for people whose medication may interfere with a skin test, or people who have chronic skin conditions that may flare up in response to the test.

Steps to Take When Allergic to Dogs But Not Cats

If you know you’re allergic to your dogs, but you’re not allergic to your cats, you can take a few precautionary steps.

The first is to make sure your dog is groomed regularly by either you or a professional groomer. They should get a weekly bath to remove dander, dust, and pollen from their fur. You might also go over their coats with a hypoallergenic solution between washes.

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Make some areas of your house, like your bedroom, a dog-free zone. Dogs won’t be allowed into the room or on the furniture. You may also want to invest in an air purifier, or think about keeping the dogs outside.


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