July 18, 2025 | Black & Kletz Allergy
Pet allergies are quite common in the United States. About 20% of the U.S. population have cat allergies and 10% of the people in the U.S. have dog allergies. Approximately 70% of the homes in the U.S. have at least 1 pet with dogs being the most common pet, followed by cats. The percentage of homes with pets is higher than in the past as more and more families are getting pets. The Labrador Retriever is the most common pet dog and the Ragdoll is the most common pet cat. There are roughly 77 million pet dogs living in the U.S, however there are only 49 million households with dogs. In other words, each dog-owning home has an average of 1.5 dogs. In contrast, there are roughly 59 million cats living in approximately 32 million homes, which is equivalent to 1.8 cats per household.
When someone says that they are allergic to a pet, they are really saying that they are allergic to one or more of the proteins that are produced in the sebaceous glands of the skin (dander), saliva, and/or urine of that animal. In dogs, the major protein responsible for their allergies is called “Can f 1.” Note that the “Can” in “Can f 1” is short for canine or dog. This protein is produced by dogs and commonly found in the dog’s dander, saliva, and urine. In cats, similarly, the major proteins associated with their allergies are called “Fel d 1” and “Fel d 4.” Note that the “Fel” in both of the proteins “Fel d 1” and “Fel d 4” is short for feline or cat.
Besides the fact that there are different proteins responsible for allergies to cats and dogs, there is also a difference in the dander between these 2 pets. Cat dander is “sticky” whereas dog dander is not. Cat dander tends to stick to walls, clothing, upholstered furniture, bedding, and carpeting. It is commonly transported from one’s house to other houses or to workplaces. An example of this phenomenon is illustrated by the fact that if the Fel d 1 protein is measured on a cat owner’s clothing or upholstered furniture at work, it is likely that the protein will be found. In addition, it usually take several months for these “allergic” proteins to dissipate and become undetectable, despite a thorough cleaning of the home, due the stick-to-itiveness of cat dander. Although cat dander is stickier than dog dander, it does not mean that dog dander cannot stick to walls, clothing, upholstered furniture, bedding, and carpeting. It just means that the proteins associated with cat dander will linger more in one’s home more than dog dander. It should also be noted that since the proteins associated with cats are also found in urine, cat litter boxes are a rich source of these proteins and cat-allergic individuals should avoid exposure to litter boxes, if at all possible.
Interestingly, there is a condition called pork-cat syndrome that may affect individuals who are allergic to cats. In this syndrome, cat-allergic individuals develop an allergy to consuming pork. The severity can be severe and even life-threatening. Pork-cat syndrome affects females much more than male individuals since approximately 80% of the people with this condition are females. Avoiding the consumption of pork is crucial in these individuals and patients with this syndrome should carry a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) or an epinephrine nasal spray (e.g., Neffy). If they use the epinephrine containing device, they should go immediately to the closest emergency room.
Another interesting fact is that there is an increased incidence of horse allergy in some individuals that have cat and/or dog allergies due to a common protein that is shared between all 3 animals. The dander is the most common way in which horses cause allergic symptoms in humans. The horse’s saliva, urine, and the fecal material dropped by horse mites are other ways that individuals are exposed to the allergenic proteins of horses. There are roughly 4 million households in the U.S. that own horses. Obviously, horses do not normally live in people’s homes, but they still cause allergic symptoms in many individuals. Recently, it has become fashionable to own miniature horses, which in some cases, do live in the homes of their owners. Living in a house with a horse in general is probably not the best idea, but for individuals with horse allergies, it is especially not a good idea.
In rodents, unlike cats and dogs, in addition to the allergenic protein being present in the urine, dander, and saliva, certain rodents such as mice contain allergenic proteins in their mouse fecal droppings. In birds, the protein responsible for their allergies is also present on their feathers, as well as urine, dander, saliva, and fecal droppings.
The symptoms of pet allergies are essentially the same as with any other environmental allergy (i.e., hay fever or allergic rhinitis) such as dust mites, pollens, and/or molds. The main difference is that sometimes when a pet licks or scratches someone, the pet-allergic individual may get an itchy rash where they are licked or scratched. Otherwise, the most common symptoms when a pet-allergic individual is in close proximity to a pet may include sneezing, runny nose, nasal congestion, sinus congestion, post-nasal drip, generalized itching, hives, itchy eyes, watery eyes, puffy eyes, and/or redness of the eyes. In patients with asthma, chest tightness, wheezing, coughing, and/or shortness of breath may occur.
The diagnosis of pet allergies begins with a comprehensive history and physical examination. Allergy testing by skin testing or occasionally blood testing is the standard procedure to further identify if someone is allergic to pets.
The treatment of pet allergies begins with avoidance. This is not always easy and most people have a close bond with their pets, which is understandable. Nevertheless, if the pet cannot be avoided, simple measures to decrease exposure to them may help remedy the situation such as keeping the pet out of the bedroom or washing the pet fairly frequently. Medications such as antihistamines, decongestants, corticosteroid nasal sprays, antihistamine nasal sprays, anticholinergic nasal sprays, leukotriene antagonists, and/or allergy eye drops may be beneficial in helping to relieve the annoying allergy symptoms. When all of the above have been taken into consideration, allergy immunotherapy (i.e., allergy shots, allergy injections, allergy desensitization, allergy hyposensitization) is a very effective treatment to alleviate and prevent pet allergy symptoms.
Black & Kletz Allergy has board certified allergy doctors in 3 convenient locations in the greater Washington, DC, Northern Virginia, and Maryland metro area. Our allergy specialists very familiar with your furry friends and can help you with your pet allergies. The allergists at Black & Kletz Allergy diagnose and treat both children and adults. We offer on-site parking in our Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA locations. The Washington, DC and McLean, VA offices are Metro accessible and the McLean office has a free shuttle that runs between the McLean office and the Spring Hill metro station on the silver line. If you are concerned that you or your child has a pet allergy or any other type of allergy or asthma, please call us to schedule an appointment. Alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day. Black & Kletz Allergy has been serving the needs of allergy and asthma sufferers in the Washington, DC metropolitan area for more than 50 years.
