When Your Pet Makes You Sneeze

The mere presence of a dog may be enough to make your eyes water and your nose run. Or perhaps cats are the culprits that make you wheeze and feel itchy. 

Millions of people in the US have pet allergies¹. With nearly 144 million dogs and cats living in US homes as of 2012², there are lots of opportunities for furry companions to make people sneeze. Studies show that the number of people with pet allergies is going up³, though the reasons why aren’t clear. Some aspects of modern life seem to predispose people to allergies. For example, hygiene, antibiotics, and city life (as opposed to living on a farm) are linked to allergic reactions^4,5.

What Are Allergies?

Every day we encounter numerous threats from the environment, some of which pose real dangers and others that cause no harm. Your body has its own elaborate defense network, called the immune system. Normally, your immune system identifies and targets foreign substances that can make you sick, such as viruses, bacteria, or fungi. Sometimes, however, it responds inappropriately and mounts an attack against an innocent bystander, which we experience as allergies.  

Itchy, watery eyes, and sneezing are common allergy symptoms, for which there are treatments but no cure. These signs might be a reaction to allergens such as pollen or peanuts. And for some people, pets are to blame. 

Pet Allergies

Pet allergy sufferers may report symptoms less than half an hour after encountering a furry animal⁶. They are sensitive to tiny particles from the animal’s skin that slough off and spread through the environment. This is called dander. When someone with an allergy is exposed to pet dander, their immune system goes into overdrive. 

Scientists have identified at least seven allergens in dog dander and eight in cat dander⁷ (although there are likely more⁸). In dog dander, four allergens fall into a category of proteins with a wide range of functions called lipocalins⁹. The major allergen in cats (though scientists aren’t sure what it does) is a protein called Fel d 1⁸. Physicians use these proteins as markers to diagnose allergies. Researchers study them to learn how they trigger immune responses and develop remedies to prevent symptoms. 

It’s unclear how allergy sufferers develop a sensitivity to dog or cat dander^6,7. They could be exposed through the skin when they pet their furry companion, inhale pet dander from dust, or through their mouth. It could also be a combination of all these. More research is needed to pinpoint the important factors. A deeper understanding could lead to better treatments and prevention. 

Overall, cat allergies are more common than dog allergies¹⁰. Cat dander appears to be especially sticky—you can find it outside the home, like in schools and even dwellings without a cat^6,8,11. Fel d 1, for instance, is small and lightweight, so it remains airborne for hours⁸. It is easily transferred via clothing and we can expose others without realizing it.  

Early Exposure Might Help

An increasing number of people have respiratory problems such as asthma and allergies. Scientists have speculated that lifestyle changes play a role since life has increasingly moved indoors and people have become more hygienic and less active¹². Studies suggest that coming into contact with some allergens early in life can decrease the chances of developing an allergy. Avoiding exposing young children to peanuts, for instance, may make allergies worse¹¹. In a similar vein, having pets in the house could help infants develop appropriate immune responses to pet dander. 

One study from 1999 found that having a pet in the first year of life was associated with a lower risk of allergy¹³. Recent studies have also supported this idea. Some found that pet ownership promotes a healthy and diverse microbiome, which appears to protect against allergies¹⁴. Others studies, however, find no links between owning a pet and allergy risk. This suggests that the relationship between early exposure and allergies may not be so simple^8,15.

Immunotherapy—a treatment that targets the immune system—has also shown some promise⁸. Patients receive increasing doses of an allergen with the goal of changing the immune response to eliminate their symptoms. However, this treatment is expensive and not always effective⁴. More studies are needed to improve immunotherapy for pet allergies.

What Should I Do If I’m Allergic?

It’s hard to have a pet allergy if you’re a pet parent or a pet lover. Though the idea of a hairless dog or cat may be tempting, people are allergic to pet dander, not the hair itself. There’s no such thing as a hypoallergenic dog or cat. Some people may be more sensitive to specific breeds while others are allergic to all of them.

Removing the pet from your house is the most effective course of action, even if it’s not the ideal scenario. For those with severe allergies, it may be the only option. There are other ways, however, to reduce exposure for people with more mild reactions¹⁶. First, restrict your pet’s access to certain rooms in the house—especially the bedroom—and clean frequently. You can also try adding air filters to remove allergens from the air. Pet dander sticks to everything, so your pet’s favorite couch and any carpeting or rugs are hazards that should be removed, or at least regularly cleaned. 

Minimizing any chance of inhaling or touching dander is also helpful, such as changing your clothes if you play with your pet or wearing a dust mask when you clean. Though there is no cure, an allergy diagnosis doesn’t need to mean the end of your relationship with your beloved pet.

References

1. Konradsen, J. R. et al. Allergy to furry animals: New insights, diagnostic approaches, and challenges. J. Allergy Clin. Immunol. 135, 616–625 (2015).
2. U.S. Pet Ownership Statistics. Available at: https://www.avma.org/KB/Resources/Statistics/Pages/Market-research-statistics-US-pet-ownership.aspx. (Accessed: 4th July 2019)
3. Arbes, S. J., Jr, Gergen, P. J., Elliott, L. & Zeldin, D. C. Prevalences of positive skin test responses to 10 common allergens in the US population: results from the third National Health and Nutrition Examination Survey. J. Allergy Clin. Immunol. 116, 377–383 (2005).
4. Virtanen, T. Immunotherapy for pet allergies. Hum. Vaccin. Immunother. 14, 807–814 (2018).
5. Hakanen, E. et al. Urban environment predisposes dogs and their owners to allergic symptoms. Sci. Rep. 8, 1585 (2018).
6. Platts-Mills, T. A. E. & Woodfolk, J. A. Allergens and their role in the allergic immune response. Immunol. Rev. 242, 51–68 (2011).
7. WHO/IUIS Allergen Nomenclature Home Page. Available at: http://allergen.org. (Accessed: 8th July 2019)
8. Bonnet, B. et al. An update on molecular cat allergens: Fel d 1 and what else? Chapter 1: Fel d 1, the major cat allergen. Allergy Asthma Clin. Immunol. 14, 14 (2018).
9. Flower, D. R. The lipocalin protein family: structure and function. Biochem. J 318 ( Pt 1), 1–14 (1996).
10. Morris, D. O. Human allergy to environmental pet danders: a public health perspective. Vet. Dermatol. 21, 441–449 (2010).
11. Woodfolk, J. A., Commins, S. P., Schuyler, A. J., Erwin, E. A. & Platts-Mills, T. A. E. Allergens, sources, particles, and molecules: Why do we make IgE responses? Allergol. Int. 64, 295–303 (2015).
12. Platts-Mills, T. A. E. The allergy epidemics: 1870-2010. J. Allergy Clin. Immunol. 136, 3–13 (2015).
13. Hesselmar, B., Aberg, N., Aberg, B., Eriksson, B. & Björkstén, B. Does early exposure to cat or dog protect against later allergy development? Clin. Exp. Allergy 29, 611–617 (1999).
14. Lynch, S. V. Gut Microbiota and Allergic Disease. New Insights. Ann. Am. Thorac. Soc. 13 Suppl 1, S51–4 (2016).
15. Chan, S. K. & Leung, D. Y. M. Dog and Cat Allergies: Current State of Diagnostic Approaches and Challenges. Allergy Asthma Immunol. Res. 10, 97–105 (2018).
16. Allergic to Your Pet? Learn about Dog and Cat Allergies. Available at: https://www.aafa.org/pet-dog-cat-allergies/. (Accessed: 2nd July 2019)