Pet Allergies

Pet allergy is an allergic reaction to proteins found in an animal’s skin cells, saliva or urine. Signs of pet allergy include those common to hay fever, such as sneezing and runny nose. Some people may also experience signs of asthma, such as wheezing and difficulty breathing.

Millions of Americans live with pets despite being allergic to them. Any furry animal, most commonly cats, and dogs, may trigger allergy symptoms like sneezing or red, itchy eyes. Pet allergies can also make asthma harder to control.

Compared with other conditions’ mechanisms, allergy mechanisms are simple and encompass three specific paths: allergic sensitization, allergy, and cross-reactivity. Allergies to pets are common. Pet allergy is an allergic reaction to proteins (allergens) found in animals’ skin cells (dander), saliva, urine, or sweat on their fur.

  • Allergic sensitization is the presence of immunoglobulin E (IgE) antibodies[1] to an allergen.
  • Allergy is the occurrence of reproducible symptoms or signs initiated by exposure to a defined stimulus at a dose tolerated by nonallergic persons and mediated by specific immunologic mechanisms. If no symptoms develop, a person could be sensitized to a particular allergen but not be allergic.
  • Cross-reactivity is the process of IgE antibodies[2] (originally developed against a given allergen) binding to homologous molecules originating from a different allergen source.

Most allergens are spread via airborne particles. Dander contains allergens formed in sebaceous gland secretions[3] and saliva. Secretions containing allergens adhere to the hair and stratum corneum[4] of the skin. When an animal sheds, tiny particles disperse into the air and remain buoyant for an extended period of time.

After the particles slowly settle onto the floor, furniture, or other items, they can be easily re-dispersed into the air. As a result, pet-sensitive people could experience allergy symptoms in the nose, eyes, and respiratory tract even if the pet is not present. Additionally, people can carry pet allergens that settled onto their clothing or hair.

For cats and dogs, the primary allergen sources are dander and saliva. Similarly, the primary allergen source in rabbits is saliva. In contrast, the primary allergen source is urine in rodents (e.g., mice, rats,) and Mustelidae (ferrets and minks). Most research laboratories experience a very high rate of staff turnover because lab workers develop allergies to rodents.

Children who are exposed to rodent urine can develop this allergy, too. Male rodents produce a larger quantity of and more condensed urine than female rodents. Dust from litter or sawdust in the bottom of cages may contribute to airborne allergens from rodents. This explains why people who commonly come in contact with male rodents are more likely to develop allergic symptoms. Symptoms range from conjunctivitis to asthma to skin reactions, which makes working with these animals difficult. People can also be allergic to animals with feathers (birds like parrots or parakeets).

Most animal allergens belong to three primary protein families: lipocalins, serum albumins, and secretoglobins.

Lipocalins are small proteins that bind and transport small hydrophobic molecules such as lipids, steroids, and pheromones. Many allergens from cats, dogs, horses, and rodents belong to the lipocalin family. More than 50% of allergens identified from furry animals belong to the lipocalin superfamily and are found in animal dander, saliva, and urine.
Serum albumins are large proteins that play a role in transporting small molecules through the bloodstream. Many allergens from mammals, birds, and fish belong to the serum albumin family. Serum albumin is commonly found in pet dander and saliva and causes an allergic reaction by inhalation and ingestion.
Secretoglobins, also known as uteroglobins, are small proteins that are found in many tissues, including the respiratory tract and the uterus. Many allergens from rodents and domestic animals belong to the secretoglobin family. Produced by the skin, salivary, and lacrimal glands, these proteins have an unknown function. Dried saliva and dandruff are spread as airborne particles and cause sensitization in susceptible people.

The most frequently observed pet allergies result from inhalation, contact, and bites. The main allergic symptoms are similar across both common and uncommon pet types. They present as rhinitis, conjunctivitis, urticaria (red, itchy welts that result from a skin reaction), and lower and upper respiratory symptoms, which can be mild to severe and rarely cause anaphylactic shock.

“Hypoallergenic” is defined as possessing decreased risk of causing an allergy in people, which means that hypoallergenic animals could still elicit allergies in humans. Researchers and breeders use several methods to make hypoallergenic animals. One method involves identifying and selectively breeding animals that produce less of the allergenic proteins found in their dander, saliva, or urine. This is done by analyzing the animal’s DNA and identifying the genes responsible for producing the allergenic proteins, then breeding animals with a lower expression of these genes.

Another approach involves modifying the animal’s genes using genetic engineering techniques such as gene editing to reduce the production of allergenic proteins. Some researchers have also developed vaccines that can desensitize allergic individuals to specific animal allergens. While these methods have shown promise in reducing allergen production in animals, more research is needed to determine their effectiveness and safety.

Allergists (allergy specialists) use skin prick tests together with a medical history and physical examinations to rule out or confirm a suspected IgE-mediated animal allergy. Diagnosticians should first use a skin prick test as it is inexpensive, easy to use, and quick to perform.

Pet allergies cannot currently be cured. The treatment goal is to control symptoms and improve patients’ functional status and well-being. Current recommendations for managing pet allergy symptoms start with exposure avoidance. Starting when animals are young, bathing them at least once weekly can reduce allergens and eliminate reactions in humans who are exposed to them.

Immediate removal of animals from the household will not alleviate symptoms if the owner has carpeting and other pieces of furniture/items that the pet slept or sat on. Mammalian allergens are stable and can persist in house dust for up to six months. Additionally, using high-efficiency particulate air (HEPA) filters and mattress encasement, vacuuming, and chemically treating carpets are alternative methods for reducing exposure to contaminated materials, but may not reduce disease severity.

Bathing a cat or dog regularly appears to reduce the quantity of allergen harbored by the pet. To effectively lower the Can f 1 concentration, owners need to bathe the animal at least twice every week because Can f 1 concentration rises rapidly, approaching baseline concentrations within three days after washing. Twice-weekly bathing can reduce the amount of recoverable Can f 1 on dogs by more than 80%, but researchers note that ideally, one would bathe the dog two to three times every week. Airborne Can f levels can fall by ruff-ly 40% but will quickly escalate. Start when the animal is young if possible.

When avoidance and reducing allergens are not enough, depending on the severity of signs, over-the-counter (OTC) medications like antihistamines or local/topical steroids may provide temporary relief of allergy symptoms. Those symptoms include runny/itchy nose or throat, sneezing, and itchy, red, or watery eyes. Combination products that contain both an antihistamine and a decongestant or an analgesic are available but should be used with caution due to the increased risk of adverse effects. Other allergy medications, besides the ones mentioned above, are used less often, including mast cell stabilizers and leukotriene antagonists.

  • Antihistamines – diphenhydramine, chlorpheniramine, clemastine, Cetirizine, desloratadine, fexofenadine, levocetirizine, and loratadine. Azelastine has nasal spray and eye drop formulation. Epinastine and olopatadine are formulated as eye drops. They block histamine and its binding to receptors, prevent histamine-caused redness, swelling, itching, and changes in secretions during an allergic response.
  • Corticosteroids – beclomethasone, ciclesonide, fluticasone furoate, mometasone, budesonide, triamcinolone, dexamethasone ophthalmic, prednisone, etc. They have an anti-inflammatory effect and are highly effective for allergies by treating the swelling and inflammation in your nose, but must be taken regularly. It may take 1 to 2 weeks before the full effect.
  • Decongestants – pseudoephedrine, phenylephrine, and oxymetazoline nasal sprays. They shrink swollen nasal tissues and blood vessels to relieve the symptoms of nasal swelling, congestion, mucus secretion, and redness. They relieve congestion and are often prescribed with antihistamines for allergies. They are for short-term use only (~5 days). Long-term use can make symptoms worse.

OTC medications are less expensive than immunotherapy, but costs vary. In a comparison of second-generation antihistamines versus montelukast, levocetirizine (Xyzal) had the best efficacy per cost value. Generic fexofenadine (Allegra), although similar in efficacy, was more expensive than levocetirizine.

 Intranasal cromolyn is the preferred initial choice for pregnant or lactating patients, as the body does not absorb it based on the route of administration. If a patient has persistent allergies, allergy medication is more effective when taken regularly. If a patient’s symptoms are uncontrolled after two to four weeks of OTC treatment, pharmacists should assess the patient’s adherence and refer them for prescription therapy if necessary.

If you have a cat, you can now buy cat food that can reduce cat allergens. One product available is Purina Pro Plan LiveClear. The food neutralizes a common allergen, Fel d1, found in cat saliva.

Allergists will consider allergy-specific immunotherapy when symptoms are uncontrolled by medications and/or avoidance measures, when adverse drug effects are intolerable, or when patients want to reduce long-term use of allergy medications.

  • Sublingual allergy immunotherapy (SLIT) tablets
  • SLIT drops
  • Subcutaneous allergy immunotherapy (SCIT)

As of 2022, the FDA has approved four SLIT tablets to treat allergic rhinitis with or without allergic conjunctivitis caused by ragweed, northern pasture grasses, and dust mites in susceptible individuals; the FDA has not approved SLIT tablets for pet allergies. SLIT drops are made from FDA-approved allergy extracts used to make SCIT shots.

However, these extracts are only FDA-approved for injection use under the skin, and they are not approved for use under the tongue. Research indicates SLIT is safe and effective. The FDA has approved SCIT for cat allergies, but not for other pet allergies. Patients who receive SCIT usually call it “allergy shots.”

SCIT should not be recommended to patients who have severe uncontrolled heart problems or asthma if they take beta-blockers[5], which are associated with more frequent reactions, more severe reactions, and reactions that are refractory to epinephrine. Additionally, allergy shots should not be recommended for pregnant women unless discussed with their obstetricians.

Both SCIT and SLIT require gradual up-titration of dosages with ongoing and multiple treatments and may take three to five years to reach desensitization. SLIT has been increasingly recommended because of its ability to modify the immune system for the long term while reducing allergy symptoms.

SLIT also showed a safer profile, only associated with mild mouth symptoms, and improved adherence compared to SCIT. SCIT and SLIT have proven to be economically viable options.

If your symptoms still aren’t controlled, talk to your healthcare provider about medications. Many over-the-counter antihistamines and decongestants will do the trick, but in severe cases, corticosteroids or leukotriene modifiers may be helpful. Talking to an allergist and getting an allergy test is the best way to determine what course of action you should take.

  1. Immunoglobulin E (IgE) is a type of antibody that plays a key role in the immune system’s response to allergies and parasitic infections. IgE antibodies are produced by a type of white blood cell called a B cell and bind to allergens, such as pollen or pet dander, triggering the release of histamine and other chemicals that cause the symptoms of an allergic reaction. IgE also plays a role in defending against parasitic infections by binding to parasites and facilitating their destruction by other immune cells. Elevated levels of IgE are often seen in individuals with allergies or parasitic infections, and testing for IgE antibodies can help diagnose these conditions. Treatments for allergies and asthma often target IgE, either by blocking its production or by blocking its ability to bind to allergens. [Back]
  2. Immunoglobulin E (IgE) antibodies are a type of antibody that are involved in the body’s response to allergens and parasitic infections. They are produced by a type of white blood cell called a B cell and attach to specific receptors on the surface of mast cells and basophils. When IgE binds to an allergen, it triggers the release of histamine and other chemicals that cause the symptoms of an allergic reaction. Elevated levels of IgE are commonly seen in individuals with allergies or parasitic infections, and testing for IgE antibodies can help diagnose these conditions. Treatments for allergies and asthma often target IgE, either by blocking its production or by blocking its ability to bind to allergens. [Back]
  3. Sebaceous gland secretions are the oily substances that are produced by the sebaceous glands, which are located in the skin. These secretions are known as sebum and are composed of a mixture of lipids, including triglycerides, fatty acids, wax esters, and cholesterol esters. Sebum plays an important role in keeping the skin lubricated and hydrated, and it also helps to protect the skin from bacteria and other harmful substances. However, overproduction of sebum can lead to skin conditions such as acne, while underproduction can result in dry skin. The amount of sebum produced by the sebaceous glands is regulated by a variety of factors, including hormones, diet, and stress. [Back]
  4. The stratum corneum is the outermost layer of the epidermis, the outermost layer of the skin. It is composed of dead skin cells that have become flattened and compacted, forming a barrier that helps to protect the skin from the environment. The stratum corneum also helps to regulate water loss from the skin and prevents the entry of harmful substances such as bacteria and chemicals. The thickness and composition of the stratum corneum can vary depending on factors such as age, skin type, and environmental factors. Certain skin conditions, such as psoriasis, can result in an overgrowth of cells in the stratum corneum, leading to thick, scaly patches on the skin. [Back]
  5. Beta-blockers are a class of drugs that block the effects of adrenaline and noradrenaline on beta receptors in the body, resulting in decreased heart rate and blood pressure. They are commonly used to treat conditions such as hypertension, angina, and arrhythmias. Beta-blockers work by binding to the beta receptors on cells in the heart and blood vessels, which reduces the activity of the sympathetic nervous system. This leads to a decrease in heart rate, force of contraction, and cardiac output, as well as a decrease in blood pressure. There are several different types of beta-blockers, including selective and non-selective agents, as well as those that are cardioselective or have intrinsic sympathomimetic activity. Beta-blockers can have side effects, such as fatigue, dizziness, and sexual dysfunction, and should be used with caution in patients with certain medical conditions. [Back]

Further Reading

  • “Pet Allergens” National Institute of Environmental Health Sciences
  • Galli SJ, Tsai M. IgE and mast cells in allergic disease. Nat Med. 2012;18(5):693-704. doi:10.1038/nm.2755
  • Palomares O, Akdis M, Martín-Fontecha M, Akdis CA. Mechanisms of immune regulation in allergic diseases: the role of regulatory T and B cells. Immunol Rev. 2017;278(1):219-236. doi:10.1111/imr.12543
  • Platts-Mills TAE. The role of immunoglobulin E in allergy and asthma. Am J Respir Crit Care Med. 2001;164(8 Pt 2):S1-S5. doi:10.1164/ajrccm.164.supplement_2.2106098
  • Galli SJ, Tsai M. IgE and mast cells in allergic disease. Nat Med. 2012;18(5):693-704. doi:10.1038/nm.2755
  • Palomares O, Akdis M, Martín-Fontecha M, Akdis CA. Mechanisms of immune regulation in allergic diseases: the role of regulatory T and B cells. Immunol Rev. 2017;278(1):219-236. doi:10.1111/imr.12543
  • “Pet Allergy” Asthma and Allergy Foundation of America
  • Platts-Mills TAE. The role of immunoglobulin E in allergy and asthma. Am J Respir Crit Care Med. 2001;164(8 Pt 2):S1-S5. doi:10.1164/ajrccm.164.supplement_2.2106098
  • Thiboutot D. Regulation of human sebaceous glands. J Invest Dermatol. 2004;123(1):1-12. doi:10.1111/j.0022-202X.2004.22725.x
  • Zouboulis CC, Jourdan E, Picardo M. Acne is an inflammatory disease and alterations of sebum composition initiate acne lesions. J Eur Acad Dermatol Venereol. 2014;28(5):527-532. doi:10.1111/jdv.12298
  • Downing DT, Stewart ME, Wertz PW, Strauss JS. Essential fatty acids and acne. J Am Acad Dermatol. 1986;14(2 Pt 1):221-225. doi:10.1016/s0190-9622(86)70026-1
  • Proksch E, Brandner JM, Jensen JM. The skin: an indispensable barrier. Exp Dermatol. 2008;17(12):1063-1072. doi:10.1111/j.1600-0625.2008.00786.x
  • Elias PM, Menon GK. Structural and lipid biochemical correlates of the epidermal permeability barrier. Adv Lipid Res. 1991;24:1-26. doi:10.1016/b978-0-12-024924-2.50006-5
  • Harding CR. The stratum corneum: structure and function in health and disease. Dermatol Ther. 2004;17 Suppl 1:6-15. doi:10.1111/j.1396-0296.2004.04s1001.x
  • Pomés A, Davies JM. Proteins of animal origin: horse, cat, and dog allergens. Methods Mol Biol. 2016;1386:121-142. doi:10.1007/978-1-4939-3283-2_9
  • Glesner J, Filep S, Vailes LD, et al. The stability of Can f 1 and its contribution to canine allergen extracts. J Allergy Clin Immunol. 2008;122(2):460-465.e1. doi:10.1016/j.jaci.2008.05.015
  • Lopata AL, Jeebhay MF. Airborne seafood allergens as a cause of occupational allergy and asthma. Curr Allergy Asthma Rep. 2013;13(3):288-297. doi:10.1007/s11882-013-0344-1
  • Satyaraj E, Gardner C, Filipi I, Cramer K. Breed-specific allergen epitopes for immunotherapy of IgE-mediated allergy in dogs. Allergy. 2019;74(10):1890-1901. doi:10.1111/all.13824
  • “Pet Dander” American Lung Association
  • Zhang Y, Liu S, Lu S, et al. Gene editing with CRISPR/Cas9 in the Chinese hamster ovary cell line to produce hypoallergenic proteins. Biotechnol Bioeng. 2019;116(12):3267-3274. doi:10.1002/bit.27140
  • Jang H, Lim S, Park S, et al. A recombinant hypoallergenic Parvalbumin protein produced from Escherichia coli and its immunotherapeutic potential. Sci Rep. 2017;7(1):13013. doi:10.1038/s41598-017-13369-9
  • Amin AN, Varker H, Prasad V, et al. The association between beta-blocker use and survival in patients with severe sepsis. Crit Care Med. 2016;44(6):1000-1007. doi:10.1097/CCM.0000000000001658
  • Atherton JJ, Sindone A, De Pasquale CG, Driscoll A. Beta-blocker therapy in heart failure: where do we go from here?. Heart Lung Circ. 2019;28(6):821-828. doi:10.1016/j.hlc.2018.10.004
  • Mitchell GA, Zois E, Rastogi S, Korantzopoulos P. A review of the pharmacological and clinical aspects of beta-blockers for the treatment of hypertension. Expert Opin Pharmacother. 2019;20(14):1751-1762. doi:10.1080/14656566.2019.1645075
  • “Pet Allergy” Mayo Clinic

Author: Doyle

I was born in Atlanta, moved to Alpharetta at 4, lived there for 53 years and moved to Decatur in 2016. I've worked at such places as Richway, North Fulton Medical Center, Management Science America (Computer Tech/Project Manager) and Stacy's Compounding Pharmacy (Pharmacy Tech).

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