Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Pets in the home: Impact on allergic disease

Elizabeth A Erwin, MD
Thomas A E Platts-Mills, MD, PhD
Section Editor
Robert A Wood, MD
Deputy Editor
Anna M Feldweg, MD


Patients ask a variety of questions regarding the impact of pets on allergic rhinitis and asthma. These relatively simple sounding questions expose a challenging area of research, and the answers to these questions are still being investigated. This topic will review several concepts that have taken shape in recent decades and discuss how these apply to common patient concerns.

The measures that patients with pet allergies can take to reduce exposure to dog and cat allergens in the home are discussed separately. (See "Allergen avoidance in the treatment of asthma and allergic rhinitis", section on 'Pets'.)


In most epidemiologic studies, a strong positive correlation is found between sensitization to cat or dog allergens and asthma [1-4] and to a lesser degree, allergic rhinitis [5]. In different cohorts, the odds ratio for asthma associated with sensitization to cat or dog ranges from 3 to 9.2, and the association is consistently highly significant. Therefore, it is important to understand whether living with a pet increases or decreases the likelihood of sensitization to pet allergens and ultimately, the risk of developing allergic disease.

When considering studies of allergic disease, it is important to understand the distinction between the terms "sensitization" and "allergy." Sensitization refers to the production of allergen-specific immunoglobulin E (IgE). Sensitization is usually demonstrated by skin testing or in vitro immunoassays for IgE to specific allergens (sometimes referred to as radioallergosorbent testing [RAST], although this term describes an antiquated form of the test).

Being sensitized to an allergen is not synonymous with being allergic to that allergen, because individuals may produce IgE to allergens in a given substance, but not develop symptoms upon exposure to that substance. Individuals are considered to have clinically significant allergy or allergic disease when they have allergen-specific IgE and develop symptoms upon exposure to substances containing that allergen. Thus, greater numbers of people are sensitized to an allergen than are clinically allergic to it. The variables that determine why some sensitized individuals have clinically meaningful allergic disease while others do not have not been fully identified. This is discussed in greater detail separately. (See "The relationship between IgE and allergic disease", section on 'Terminology'.)

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:

Subscribers log in here

Literature review current through: Nov 2017. | This topic last updated: Feb 22, 2017.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Remes ST, Castro-Rodriguez JA, Holberg CJ, et al. Dog exposure in infancy decreases the subsequent risk of frequent wheeze but not of atopy. J Allergy Clin Immunol 2001; 108:509.
  2. Stoltz DJ, Jackson DJ, Evans MD, et al. Specific patterns of allergic sensitization in early childhood and asthma & rhinitis risk. Clin Exp Allergy 2013; 43:233.
  3. Bufford JD, Reardon CL, Li Z, et al. Effects of dog ownership in early childhood on immune development and atopic diseases. Clin Exp Allergy 2008; 38:1635.
  4. Sandin A, Björkstén B, Bråbäck L. Development of atopy and wheezing symptoms in relation to heredity and early pet keeping in a Swedish birth cohort. Pediatr Allergy Immunol 2004; 15:316.
  5. Arshad SH, Tariq SM, Matthews S, Hakim E. Sensitization to common allergens and its association with allergic disorders at age 4 years: a whole population birth cohort study. Pediatrics 2001; 108:E33.
  6. Hesselmar B, Aberg N, Aberg B, et al. Does early exposure to cat or dog protect against later allergy development? Clin Exp Allergy 1999; 29:611.
  7. Hesselmar B, Aberg B, Eriksson B, et al. High-dose exposure to cat is associated with clinical tolerance--a modified Th2 immune response? Clin Exp Allergy 2003; 33:1681.
  8. Sporik R, Ingram JM, Price W, et al. Association of asthma with serum IgE and skin test reactivity to allergens among children living at high altitude. Tickling the dragon's breath. Am J Respir Crit Care Med 1995; 151:1388.
  9. Ingram JM, Sporik R, Rose G, et al. Quantitative assessment of exposure to dog (Can f 1) and cat (Fel d 1) allergens: relation to sensitization and asthma among children living in Los Alamos, New Mexico. J Allergy Clin Immunol 1995; 96:449.
  10. Sporik R, Squillace SP, Ingram JM, et al. Mite, cat, and cockroach exposure, allergen sensitisation, and asthma in children: a case-control study of three schools. Thorax 1999; 54:675.
  11. Custovic A, Simpson BM, Simpson A, et al. Current mite, cat, and dog allergen exposure, pet ownership, and sensitization to inhalant allergens in adults. J Allergy Clin Immunol 2003; 111:402.
  12. Platts-Mills T, Vaughan J, Squillace S, et al. Sensitisation, asthma, and a modified Th2 response in children exposed to cat allergen: a population-based cross-sectional study. Lancet 2001; 357:752.
  13. Erwin EA, Wickens K, Custis NJ, et al. Cat and dust mite sensitivity and tolerance in relation to wheezing among children raised with high exposure to both allergens. J Allergy Clin Immunol 2005; 115:74.
  14. Perzanowski MS, Rönmark E, Platts-Mills TA, Lundbäck B. Effect of cat and dog ownership on sensitization and development of asthma among preteenage children. Am J Respir Crit Care Med 2002; 166:696.
  15. Ownby DR, Johnson CC, Peterson EL. Exposure to dogs and cats in the first year of life and risk of allergic sensitization at 6 to 7 years of age. JAMA 2002; 288:963.
  16. Lødrup Carlsen KC, Roll S, Carlsen KH, et al. Does pet ownership in infancy lead to asthma or allergy at school age? Pooled analysis of individual participant data from 11 European birth cohorts. PLoS One 2012; 7:e43214.
  17. Platts-Mills TA, Perzanowski M, Woodfolk JA, Lundback B. Relevance of early or current pet ownership to the prevalence of allergic disease. Clin Exp Allergy 2002; 32:335.
  18. Perzanowski MS, Ronmark E, James HR, et al. Relevance of specific IgE antibody titer to the prevalence, severity, and persistence of asthma among 19-year-olds in northern Sweden. J Allergy Clin Immunol 2016; 138:1582.
  19. Reefer AJ, Hulse KE, Lannigan JA, et al. Flow cytometry imaging identifies rare T(H)2 cells expressing thymic stromal lymphopoietin receptor in a "proallergic" milieu. J Allergy Clin Immunol 2010; 126:1049.
  20. Campbell JD, Buckland KF, McMillan SJ, et al. Peptide immunotherapy in allergic asthma generates IL-10-dependent immunological tolerance associated with linked epitope suppression. J Exp Med 2009; 206:1535.
  21. Luczynska CM, Li Y, Chapman MD, Platts-Mills TA. Airborne concentrations and particle size distribution of allergen derived from domestic cats (Felis domesticus). Measurements using cascade impactor, liquid impinger, and a two-site monoclonal antibody assay for Fel d I. Am Rev Respir Dis 1990; 141:361.
  22. Custis NJ, Woodfolk JA, Vaughan JW, Platts-Mills TA. Quantitative measurement of airborne allergens from dust mites, dogs, and cats using an ion-charging device. Clin Exp Allergy 2003; 33:986.
  23. de Blay F, Heymann PW, Chapman MD, Platts-Mills TA. Airborne dust mite allergens: comparison of group II allergens with group I mite allergen and cat-allergen Fel d I. J Allergy Clin Immunol 1991; 88:919.
  24. Custovic A, Simpson A, Pahdi H, et al. Distribution, aerodynamic characteristics, and removal of the major cat allergen Fel d 1 in British homes. Thorax 1998; 53:33.
  25. Bollinger ME, Eggleston PA, Flanagan E, Wood RA. Cat antigen in homes with and without cats may induce allergic symptoms. J Allergy Clin Immunol 1996; 97:907.
  26. Platts-Mills JA, Custis NJ, Woodfolk JA, Platts-Mills TA. Airborne endotoxin in homes with domestic animals: implications for cat-specific tolerance. J Allergy Clin Immunol 2005; 116:384.
  27. Gelber LE, Seltzer LH, Bouzoukis JK, et al. Sensitization and exposure to indoor allergens as risk factors for asthma among patients presenting to hospital. Am Rev Respir Dis 1993; 147:573.
  28. Kaiser L, Grönlund H, Sandalova T, et al. The crystal structure of the major cat allergen Fel d 1, a member of the secretoglobin family. J Biol Chem 2003; 278:37730.
  29. Platts-Mills TA, Woodfolk JA. Allergens and their role in the allergic immune response. Immunol Rev 2011; 242:51.
  30. Mandhane PJ, Sears MR, Poulton R, et al. Cats and dogs and the risk of atopy in childhood and adulthood. J Allergy Clin Immunol 2009; 124:745.
  31. Wegienka G, Johnson CC, Havstad S, et al. Lifetime dog and cat exposure and dog- and cat-specific sensitization at age 18 years. Clin Exp Allergy 2011; 41:979.
  32. Wegienka G, Havstad S, Kim H, et al. Subgroup differences in the associations between dog exposure during the first year of life and early life allergic outcomes. Clin Exp Allergy 2017; 47:97.
  33. Fujimura KE, Johnson CC, Ownby DR, et al. Man's best friend? The effect of pet ownership on house dust microbial communities. J Allergy Clin Immunol 2010; 126:410.
  34. Campo P, Kalra HK, Levin L, et al. Influence of dog ownership and high endotoxin on wheezing and atopy during infancy. J Allergy Clin Immunol 2006; 118:1271.
  35. Ownby DR, Peterson EL, Wegienka G, et al. Are cats and dogs the major source of endotoxin in homes? Indoor Air 2013; 23:219.
  36. Gereda JE, Leung DY, Thatayatikom A, et al. Relation between house-dust endotoxin exposure, type 1 T-cell development, and allergen sensitisation in infants at high risk of asthma. Lancet 2000; 355:1680.
  37. Liu AH. Something old, something new: indoor endotoxin, allergens and asthma. Paediatr Respir Rev 2004; 5 Suppl A:S65.
  38. Karvonen AM, Hyvärinen A, Rintala H, et al. Quantity and diversity of environmental microbial exposure and development of asthma: a birth cohort study. Allergy 2014; 69:1092.
  39. Sohy C, Pons F, Casset A, et al. Low-dose endotoxin in allergic asthmatics: effect on bronchial and inflammatory response to cat allergen. Clin Exp Allergy 2006; 36:795.
  40. Takenaka T, Kuribayashi K, Nakamine H, et al. Regulation by cytokines of eosinophilopoiesis and immunoglobulin E production in mice. Immunology 1993; 78:541.
  41. Kishimoto T, Ishizaka K. Regulation of antibody response in vitro. VI. Carrier-specific helper cells for IgG and IgE antibody response. J Immunol 1973; 111:720.
  42. Blackley CH. Experimental researches on the causes and nature of Catarrhus aestivus (Hay fever or Hay asthma), Bailliere, Tindall & Cox, London 1873. Reprinted in 1959.
  43. Ege MJ, Mayer M, Normand AC, et al. Exposure to environmental microorganisms and childhood asthma. N Engl J Med 2011; 364:701.
  44. Olivieri M, Zock JP, Accordini S, et al. Risk factors for new-onset cat sensitization among adults: a population-based international cohort study. J Allergy Clin Immunol 2012; 129:420.
  45. Liccardi G, Salzillo A, Cecchi L, et al. Is cat-keeping the main determinant of new-onset adulthood cat sensitization? J Allergy Clin Immunol 2012; 129:1689.
  46. Erwin EA, Woodfolk JA, James HR, et al. Changes in cat specific IgE and IgG antibodies with decreased cat exposure. Ann Allergy Asthma Immunol 2014; 112:545.
  47. Carter MC, Perzanowski MS, Raymond A, Platts-Mills TA. Home intervention in the treatment of asthma among inner-city children. J Allergy Clin Immunol 2001; 108:732.
  48. Svanes C, Heinrich J, Jarvis D, et al. Pet-keeping in childhood and adult asthma and hay fever: European community respiratory health survey. J Allergy Clin Immunol 2003; 112:289.
  49. Svanes C, Zock JP, Antó J, et al. Do asthma and allergy influence subsequent pet keeping? An analysis of childhood and adulthood. J Allergy Clin Immunol 2006; 118:691.
  50. Anyo G, Brunekreef B, de Meer G, et al. Early, current and past pet ownership: associations with sensitization, bronchial responsiveness and allergic symptoms in school children. Clin Exp Allergy 2002; 32:361.
  51. Bousquet J, Heinzerling L, Bachert C, et al. Practical guide to skin prick tests in allergy to aeroallergens. Allergy 2012; 67:18.
  52. Kwong KY, Eghrari-Sabet JS, Mendoza GR, et al. The benefits of specific immunoglobulin E testing in the primary care setting. Am J Manag Care 2011; 17 Suppl 17:S447.