Cat and dog ownership during/after the first year of life and risk for sensitization and reported allergy symptoms at age 13

The influence of lifestyle and environmental factors on host resilience through a homeostatic skin microbiota: An EAACI Task Force Report

Human skin is colonized with skin microbiota that includes commensal bacteria, fungi, arthropods, archaea and viruses. The composition of the microbiota varies at different anatomical locations according to changes in body temperature, pH, humidity/hydration or sebum content. A homeostatic skin microbiota is crucial to maintain epithelial barrier functions, to protect from invading pathogens and to interact with the immune system. Therefore, maintaining homeostasis holds promise to be an achievable goal for microbiome-directed treatment strategies as well as a prophylactic strategy to prevent the development of skin diseases, as dysbiosis or disruption of homeostatic skin microbiota is associated with skin inflammation. A healthy skin microbiome is likely modulated by genetic as well as environmental and lifestyle factors. In this review, we aim to provide a complete overview of the lifestyle and environmental factors that can contribute to maintaining the skin microbiome healthy. Awareness of these factors could be the basis for a prophylactic strategy to prevent the development of skin diseases or to be used as a therapeutic approach.

Minimizing Indoor Allergen Exposure: What Works?

PURPOSE OF REVIEW

Allergic rhinitis and asthma morbidity has been linked to indoor allergen exposure. Common indoor allergens include dust mites, cats, dogs, rodents, and cockroaches. These allergens are ubiquitous and often difficult to remove from the home, making long-lasting reduction strategies difficult to achieve. Identifying strategies for reducing the presence of indoor allergens in homes could be utilized to decrease allergic disease burden, improve symptomology, reduce healthcare costs, and improve patients' quality of life.

RECENT FINDINGS

Studies have yielded mixed results with regard to specific environmental control measures in reducing indoor allergen levels and in improving clinical outcomes of allergic disease. In this review, we assess the available evidence of the effectiveness of environmental control measures in reducing indoor allergens and the potential clinical impact of these measures.

Dog Allergy in Children: A Single-Centered Study

INTRODUCTION

Dogs are among the most commonly allergenic pets for children. Data on risk factors for the development of dog allergy are scarce. This study aimed to evaluate the characteristics of children with dog allergy and identify predictors of symptom development with dog exposure.

METHODS

The study included children with dog allergen sensitization demonstrated by skin prick test (SPT) between September 1, 2019, and December 1, 2022. Demographic, clinical, and laboratory data were collected from the patients' records and interviews with parents.

RESULTS

Dog allergen sensitization was detected by SPT in 548 (5.5%) of 9,907 patients. Of these, 507 patients had complete data and were included in the analysis. The patients' median age was 11 (IQR: 8-15) years, 55.8% were male, 97.6% exhibited polysensitization (pollen 75.1%, cat 69.6%), 83.6% had allergic rhinitis, and 46.2% had asthma. Acute dog exposure caused symptoms in 164 patients (32.3%), most commonly sneezing (n = 97) and nasal symptoms (n = 80). Predictors of acute symptoms in dog-sensitized children were male sex (OR: 0.584 [CI: 0.38-0.87]), dog exposure before 1 year of age (OR: 2.35 [CI: 1.18-4.66]), close contact with a dog owner (OR: 2.93 [CI: 1.78-4.8]), and cat allergy (OR: 2.75 [CI: 1.82-4.1]).

CONCLUSION

Approximately one-third of children with dog sensitization developed symptoms after exposure to the dog. Male sex, direct dog exposure before the age of one, close contact with a dog owner, and cat allergy were identified as predictors of dog allergy.

Treatment of Allergies to Fur Animals

Allergy to fur animals is becoming an increasingly common clinical problem in everyday medical practice. Depending on the route of exposure to the allergen, patients present with many, often non-specific symptoms. The most common illnesses among people with allergies to the above-mentioned allergens are as follows: allergic rhinitis, allergic conjunctivitis, atopic bronchial asthma, food allergy, allergic contact dermatitis, and sometimes anaphylactic shock. In recent years, there has been a change in the holistic approach to the treatment of allergy patients. The method of treatment should be tailored to a specific patient, taking into account his or her predispositions, economic possibilities, and therapeutic goals. The article describes the main methods of treating allergies, focusing primarily on allergies to fur animals. Allergy treatment always requires great care, and qualification for specific types of therapy should be preceded by a thorough and accurate diagnosis.

Associations of the placental metabolome with immune maturation up to one year of age in the Swedish NICE-cohort

INTRODUCTION

Allergies and other immune-mediated diseases are thought to result from incomplete maturation of the immune system early in life. We previously showed that infants' metabolites at birth were associated with immune cell subtypes during infancy. The placenta supplies the fetus with nutrients, but may also provide immune maturation signals.

OBJECTIVES

To examine the relationship between metabolites in placental villous tissue and immune maturation during the first year of life and infant and maternal characteristics (gestational length, birth weight, sex, parity, maternal age, and BMI).

METHODS

Untargeted metabolomics was measured using Liquid Chromatography-Mass Spectrometry. Subpopulations of T and B cells were measured using flow cytometry at birth, 48 h, one, four, and 12 months. Random forest analysis was used to link the metabolomics data with the T and B cell sub populations as well as infant and maternal characteristics.

RESULTS

Modest associations (Q2 = 0.2-0.3) were found between the placental metabolome and kappa-deleting recombination excision circles (KREC) at birth and naïve B cells and memory T cells at 12 months. Weak associations were observed between the placental metabolome and sex and parity. Still, most metabolite features of interest were of low intensity compared to associations previously found in cord blood, suggesting that underlying metabolites were not of placental origin.

CONCLUSION

Our results indicate that metabolomic measurements of the placenta may not effectively recognize metabolites important for immune maturation.

The Primary Prevention of Atopy: Does Early Exposure to Cats and Dogs Prevent the Development of Allergy and Asthma in Children? A Comprehensive Analysis of the Literature

The current literature shows mixed results relating to the significance of environmental exposure, such as owning a pet, and the development of atopy in children. Our review aimed to collect the most recent evidence on the association between early-life cat and dog ownership and the development of allergy and asthma. A comprehensive literature review was performed using PubMed and Scopus. The search included the main keywords of our PICO: (((early exposure) AND (children) AND (allergy)) OR (asthma)) AND (dog) OR (cat). Randomized controlled trials (RCTs), case-control studies, clinical trials, meta-analyses, and systematic reviews of children within the last five years (2018-2023) were searched and included. During the search process, 52 articles from PubMed and 43 from Scopus were found. A total of 17 articles were deemed to be suitable and included. Fairly consistent results regarding early exposure to pets, in particular dogs, and the prevention of food allergies have been described. Furthermore, there seems to be a protective effect against allergy and asthma in relation to the number of pets owned. The likelihood of a child developing allergy and asthma seems to be influenced by various factors, including the child's genetic background and early exposure to different environmental factors, including allergens that may interact with the gut microbiota and immune system.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

[The impact of specialized management on allergic asthma outcomes]

INTRODUCTION

Allergic asthma has variable characteristics depending on the region of occurrence. Management is often organized without easy access to a specialized pneumo-allergological evaluation.

OBJECTIVES

PRIMARY: To characterize allergic asthma in patients followed at the Nancy University Hospital.

SECONDARY

To estimate the impact at 12 months of the proposed specialized management.

METHOD

Retrospective study including allergic asthmatic adults conducted between 01/01/2016 and 31/12/2018. Parameters studied (aside from descriptive parameters): asthma control score ACQ-7 (Asthma Control Questionnaire) and lung function at inclusion and at one year.

RESULTS

One hundred and fifteen patients were included (age 42±16 years, women 63%, non-smokers 70%). Even though asthma symptoms arose at 19±18 years, the specialized consultation was performed 21±17.5 years later. Frequent sensitizations involved house dust mites (49%), cat dander (43%), grasses (43%). Patients tended to underestimate the frequency of their allergies (mites 36% P=0.011, pollens 36% P=0.001, pet dander 42% P=0.003, molds 80% P=0.007). At 1-year follow-up both the ACQ-7 score (1.3±1.3 vs. 0.8±0.9; P=0.007) and the forced expiratory volume per second (81.3±20.8% vs. 86.2±21.9%; P=0.002) had improved.

CONCLUSION

The specificities of allergic asthmatics followed up in Nancy: late age of asthma onset of asthma and specialized consultation; predominant sensitization to cat dander and Betulaceae pollens; underestimation of allergies by the patient. Specialized care seems to important in the management of allergic asthma. While access to specialized care remains problematic, it could be facilitated by the creation of dedicated networks.

Biomass Smoke Exposure and Atopy among Young Children in the Western Highlands of Guatemala: A Prospective Cohort Study

Women and children in rural regions of low-income countries are exposed to high levels of household air pollution (HAP) as they traditionally tend to household chores such as cooking with biomass fuels. Early life exposure to air pollution is associated with aeroallergen sensitization and developing allergic diseases at older ages. This prospective cohort study assigned HAP-reducing chimney stoves to 557 households in rural Guatemala at different ages of the study children. The children's air pollution exposure was measured using personal CO diffusion tubes. Allergic outcomes at 4-5 years old were assessed using skin prick tests and International Study of Asthma and Allergies in Childhood (ISAAC)-based questionnaires. Children assigned to improved stoves before 6 months old had the lowest HAP exposure compared to the other groups. Longer exposure to the unimproved stoves was associated with higher risks of maternal-reported allergic asthma (OR = 2.42, 95% CI: 1.11-5.48) and rhinitis symptoms (OR = 2.01, 95% CI: 1.13-3.58). No significant association was found for sensitization to common allergens such as dust mites and cockroaches based on skin prick tests. Reducing HAP by improving biomass burning conditions might be beneficial in preventing allergic diseases among children in rural low-income populations.

The association of timothy grass allergy and cat ownership on cat sensitization

Background: Pollen hypersensitivity might be a determining factor for other nonseasonal allergens because it may indicate deviation of the immune system toward T-helper type 2 activity and immunoglobulin E sensitivity. Objective: To investigate whether timothy grass pollen allergy may be a predictive factor for cat sensitization and whether there is an association between sensitivity to both allergens. Method: A retrospective review was made of patients with symptoms of rhinitis. The skin-prick test results and cat ownership status of the patients were analyzed. On the basis of the skin-prick test results with Phleum pratense (timothy grass) and other pollens, the patients were analyzed in two groups: "timothy allergic" and "non-timothy allergic." Results: A total of 383 patients with the diagnosis of rhinitis were included in the study, which comprised 213 (55.6%) in the timothy allergic group and 170 (44.4%) in the non-timothy allergic group. The frequency of cat sensitization was significantly higher in the patients in the timothy allergic group compared with those without timothy grass allergy (33.8% versus 12.3%; p < 0.001). No significant difference was determined between the two groups in terms of cat ownership (p = 0.63). In the logistic regression analysis, cat ownership (adjusted odds ratio [OR] 23.07 [95% confidence interval {CI}, 7.72-68.91]) and timothy allergy (adjusted OR 7.72 [95% CI, 3.16-18.86]) were associated with an increased risk of cat sensitization. Conclusion: Timothy grass allergy may play a role in the development of cat sensitization; however, further research is needed to clarify these associations and the underlying mechanisms.

S3 guideline Allergy Prevention

BACKGROUND

The persistently high prevalence of allergic diseases in Western industrial nations and the limited possibilities of causal therapy make evidence-based recommendations for primary prevention necessary.

METHODS

The recommendations of the S3 guideline Allergy Prevention, published in its last version in 2014, were revised and consulted on the basis of a current systematic literature search. The evidence search was conducted for the period 06/2013 - 11/2020 in the electronic databases Cochrane and MEDLINE, as well as in the reference lists of current reviews and through references from experts. The literature found was screened in two filtering processes, first by title and abstract, and the remaining papers were screened in the full text for relevance. The studies included after this were sorted by level of evidence, and the study quality was indicated in terms of potential bias (low/high). The revised recommendations were formally agreed and consented upon with the participation of representatives of the relevant professional societies and (self-help) organizations (nominal group process). Of 5,681 hits, 286 studies were included and assessed.

RESULTS

Recommendations on maternal nutrition during pregnancy and breastfeeding as well as on infant nutrition in the first months of life again play an important role in the updated guideline: Many of the previous recommendations were confirmed by the current data. It was specified that breastfeeding should be exclusive for the first 4 - 6 months after birth, if possible, and that breastfeeding should continue with the introduction of complementary foods. A new recommendation is that supplementary feeding of cow's milk-based formula should be avoided in the first days of life if the mother wishes to breastfeed. Furthermore, it was determined that the evidence for a clear recommendation for hydrolyzed infant formula in non-breastfed infants at risk is currently no longer sufficient. It is therefore currently recommended to check whether an infant formula with proven efficacy in allergy prevention studies is available until the introduction of complementary feeding. Finally, based on the EAACI guideline, recommendations were made for the prevention of chicken egg allergy by introducing and regularly giving thoroughly heated (e.g., baked or hard-boiled) but not "raw" chicken egg (also no scrambled egg) with the complementary food. The recommendation to introduce peanut in complementary feeding was formulated cautiously for the German-speaking countries: In families who usually consume peanut, the regular administration of peanut-containing foods in age-appropriate form (e.g., peanut butter) with the complementary diet can be considered for the primary prevention of peanut allergy in infants with atopic dermatitis (AD). Before introduction, a clinically relevant peanut allergy must be ruled out, especially in infants with moderate to severe AD. There is still insufficient evidence for an allergy-preventive efficacy of prebiotics or probiotics, vitamin D, or other vitamins in the form of supplements so that recommendations against their supplementation were adopted for the first time in the current guideline. Biodiversity plays an important role in the development of immunological tolerance to environmental and food allergens: there is clear evidence that growing up on a farm is associated with a lower risk of developing asthma and allergic diseases. This is associated with early non-specific immune stimulation due to, among other things, the greater microbial biodiversity of house dust in this habitat. This aspect is also reflected in the recommendations on animal husbandry, on which a differentiated statement was made: In families without a recognizable increased allergy risk, pet keeping with cats or dogs should not generally be restricted. Families with an increased allergy risk or with children with already existing AD should not acquire a new cat - in contrast, however, dog ownership should not be discouraged. Interventions to reduce exposure to dust mite allergens in the home, such as the use of mite allergen-proof mattress covers ("encasings"), should be restricted to patients with already proven specific sensitization against house dust mite allergen. Children born by caesarean section have a slightly increased risk of asthma - this should be taken into account when advising on mode of delivery outside of emergency situations. Recent work also supports the recommendations on air pollutants: Active and passive exposure to tobacco smoke increase the risk of allergies, especially asthma, and should therefore be avoided. Exposure to nitrogen oxides, ozone, and small particles (PM 2.5) is associated with an increased risk, especially for asthma. Therefore, exposure to emissions of nitrogen oxides, ozone, and small particles (PM 2.5) should be kept low. The authors of this guideline are unanimously in favor of enacting appropriate regulations to minimize these air pollutants. There is no evidence that vaccinations increase the risk of allergies, but conversely there is evidence that vaccinations can reduce the risk of allergies. All children, including children at risk, should be vaccinated according to the current recommendations of the national public health institutes, also for reasons of allergy prevention.

CONCLUSION

The consensus of recommendations in this guideline is based on an extensive evidence base. The update of the guideline enables evidence-based and up-to-date recommendations for the prevention of allergic diseases including asthma and atopic dermatitis.

The role of environmental allergen control in the management of asthma

Allergen exposure may exacerbate asthma symptoms in sensitized patients. Allergen reduction or avoidance measures have been widely utilized; however, there is ongoing controversy on the effectiveness of specific allergen control measures in the management of children with asthma. Often, allergen avoidance strategies are not recommended by guidelines because they can be complex or burdensome, although individual patients may benefit. Here we explore the potential for intervention against exposure to the major allergens implicated in asthma (ie, house dust mites, indoor molds, rodents, cockroaches, furry pets, and outdoor molds and pollens), and subsequent effects on asthma symptoms. We critically assess the available evidence regarding the clinical benefits of specific environmental control measures for each allergen. Finally, we underscore the need for standardized and multifaceted approaches in research and real-life settings, which would result in the identification of more personalized and beneficial prevention strategies.

Associations of early-life pet ownership with asthma and allergic sensitization: a meta-analysis of >77,000 children from the EU Child Cohort Network

BACKGROUND

Studies examining associations of early-life cat and dog ownership with childhood asthma have reported inconsistent results. Several factors could explain these inconsistencies, including type of pet, timing and degree of exposure.

OBJECTIVE

To study associations of early-life cat and dog ownership with school-age asthma, including the role of type (cat versus dog), timing (never, prenatal or early childhood) and degree (number) of ownership, and the role of allergic sensitisation.

METHODS

We used harmonised data from 77,434 mother-child dyads aged 5-11 years from nine birth cohorts in the EU Child Cohort Network. Associations were examined through the DataSHIELD platform using adjusted logistic regression models, fitted separately for each cohort and combined using random-effects meta-analysis.

RESULTS

Early-life cat and dog ownership ranged between 12-45% and 7-47% respectively, and prevalence of asthma between 2-20%. There was no overall association between either cat or dog ownership and asthma (OR: 0.97 (95% CI: 0.87-1.09) and 0.92 (0.85-1.01), respectively). Timing and degree of ownership did not strongly influence associations. Cat and dog ownership were also not associated with cat- and dog-specific allergic sensitisation (OR: 0.92 (0.75-1.13) and 0.93 (0.57-1.54), respectively). However, cat- and dog-specific allergic sensitisation were strongly associated with school-age asthma (OR: 6.69 (4.91-9.10) and 5.98 (3.14-11.36), respectively). There was also some indication of an interaction between ownership and sensitisation, suggesting that ownership may exacerbate the risks associated with pet-specific sensitisation, but offer some protection against asthma in the absence of sensitisation.

CONCLUSION

Our findings do not support early-life cat and dog ownership in themselves increasing the risk of school-age asthma, but suggest that ownership may potentially exacerbate the risks associated with cat- and dog-specific allergic sensitisation.

A Cross-Sectional Study of Knowledge on Ownership, Zoonoses and Practices among Pet Owners in Northern Portugal

Simple Summary

Pet ownership is common in most countries, but few published studies have addressed pet owners’ knowledge of zoonoses, pet contact practices, or awareness of zoonotic disease risks posed by pets. The aim of this study was to assess household knowledge, attitudes, and risks related to pet ownership and zoonoses in northern Portugal. A questionnaire was developed to gather information regarding participants’ demographic characteristics; household pet types and their importance to the family; pet contact-related attitudes; knowledge of zoonoses, high-risk groups, disease transmission pathways, and disease protection measures. It was observed that most participants considered pets an important part of the family. Nevertheless, high-risk practices were recurrent and pet owners’ knowledge was limited. These results reinforce the importance of further studies to better understand the existing gaps in knowledge of pet ownership and zoonoses and strengthens the need to adopt the One Health concept.

Abstract

Pet ownership is common in modern society. In Portugal, 38% and 31% of all households own at least one dog or cat, respectively. Few studies have ascertained the knowledge of pet owners on pet ownership and zoonoses, and none have been carried out in Portugal. The aim of the present study was to assess household knowledge and practices related to pet ownership and zoonoses in northern Portugal. A face-to-face questionnaire was completed by 424 pet owners, from November 2019 to February 2020. Most respondents (97.2%) considered pets as an important part of the family, especially women (p = 0.036); 73.1% allowed their pets to live an indoor/outdoor life; 41.3% denied sharing the bed with their pets while 29% assumed they did it daily; 20.3% reported never kissing their pets/pets licking their faces. Furthermore, 73.6% considered animals as potential sources of human diseases, but only 25.9% reported knowing the definition of zoonoses; 96.9% considered the role of veterinarians important in protecting public health. The low level of knowledge of pet owners and the occurrence of high-risk behaviors indicates a need to strengthen communication between veterinarians, physicians, pet owners, and the general public towards reduce the risk of acquisition and transmission of zoonoses.

Associations of maternal and infant metabolomes with immune maturation and allergy development at 12 months in the Swedish NICE-cohort

Allergic diseases are the most common chronic diseases in childrenin the Western world, but little is know about what factors influence immune maturation and allergy development. We therefore aimed to associate infant and maternal metabolomes to T- and B-cell subpopulations and allergy diagnosis. We performed liquid chromatography-mass spectrometry based untargeted metabolomics on blood plasma from mothers (third trimester, n = 605; delivery, n = 558) and from the umbilical cord (n = 366). The measured metabolomes were associated to T- and B-cell subpopulations up to 4 months after delivery and to doctor´s diagnosed eczema, food allergy and asthma at one year of age using random forest analysis. Maternal and cord plasma at delivery could predict the number of CD24+CD38low memory B-cells (p = 0.033, n = 26 and p = 0.009, n = 22), but future allergy status could not be distinguished from any of the three measured metabolomes. Replication of previous literature findings showed hypoxanthine to be upregulated in the umbilical cord of children with subsequent asthma. This exploratory study suggests foetal immune programming occuring during pregnancy as the metabolomic profiles of mothers and infants at delivery related to infants' B-cell maturation.

Pet ownership in pregnancy and methylation pattern in cord blood

Having pets in the house during the first years of life has been shown to protect against allergies. However, the result of different studies is heterogeneous. The aim of this study was to evaluate the methylation pattern in cord blood in relation to pet ownership during pregnancy.We investigated the methylation patterns of 96 cord blood samples, participants of the Epigenetic Hallmark of Maternal Atopy and Diet-ELMA project, born to mothers who either owned pets (n = 32) or did not own pets (n = 64) during their pregnancy. DNA from cord blood was analysed using the Infinium methylation EPIC. For statistical analysis, RnBeads software was applied.We found 113 differentially methylated sites (DMs) in the covariate-adjusted analysis (FDR p < 0.05), with small methylation differences. The top DMs were associated with genes: UBA7, THRAP3, GTDC1, PDE8A and SBK2. In the regional analysis, two promoter regions presented with significance: RN7SL621P and RNU6-211P. Cis-regulatory element analysis revealed significant associations with several immune-related pathways, such as regulation of IL18, Toll signalling, IL6 and complement.We conclude that pet exposure during pregnancy causes subtle but significant changes in methylation patterns in cord blood, which are reflected in the biological processes governing both innate and adaptive immune responses.

A butterfly flaps its wings: Extinction of biological experience and the origins of allergy

OBJECTIVE

To explore links between biodiversity on all scales and allergic disease as a measure of immune dysregulation.

DATA SOURCES

PubMed and Web of Science were searched using the keywords biodiversity, nature relatedness, allergic disease, microbiome, noncommunicable diseases, coronavirus disease 2019, and associated terms.

STUDY SELECTIONS

Studies were selected based on relevance to human health and biodiversity.

RESULTS

Contact with natural environments enriches the human microbiome, promotes regulated immune responses, and protects against allergy and both acute and chronic inflammatory disorders. These important links to ecopsychological constructs of the extinction of experience, which indicates that loss of direct, personal contact with biodiversity (wildlife and the more visible elements of the natural world), might lead to emotional apathy and irresponsible behaviors toward the environment.

CONCLUSION

The immune system is a useful early barometer of environmental effects and, by means of the microbiome, is a measure of the way in which our current experiences differ from our ancestral past. Although we would benefit from further research, efforts to increase direct, personal contact with biodiversity have clear benefits for multiple aspects of physical and mental health, the skin and gut microbiome, immune function, food choices, sleep, and physical activity and promote environmental responsibility.

Cat and dog ownership during/after the first year of life and risk for sensitization and reported allergy symptoms at age 13

BACKGROUND

Avoidance of pets as a strategy for preventing atopic diseases has been questioned. This study aimed to identify the risk of sensitization and allergic symptoms at age 13 in relation to dog- and cat-keeping during and after the first year of life.

METHODS

The study included all children born at Östersund Hospital in Northern Sweden between February 1996 and January 1997 (n = 1231). At inclusion, parents were asked to answer questionnaires about lifestyle, including cat- and dog-keeping. Dog allergy, cat allergy, hay fever, and asthma were diagnosed based on parental reported allergic symptoms at 13 years of age (n = 834). The risks of sensitization or allergy in relation to dog- and cat-keeping during and after the first year of life were analyzed with logistic regression. To adjust for reverse causation, all subjects that had reported avoidance of pets due to allergic symptoms of the child or allergy in the family (n = 177) were excluded.

RESULTS

Dog- or cat-keeping during the first year of life reduced the risk of sensitization to dog or cat allergens, respectively, and to birch and to at least one of the 10 allergens tested. Cat-keeping, both during and after the first year of life, reduced the risk of cat allergy and hay fever. Having a dog at home during the first year of life reduced the risk of dog and cat allergy, whereas dog-keeping after the first year of life did not affect allergic symptoms.

CONCLUSIONS

Cat ownership, either during or after the first year of life, may be a strategy for preventing the development of cat allergy and hay fever later in life. Dog ownership reduced the risk of sensitization to dog and birch allergen, and also the risk of cat and dog allergy, but had no effect on hay fever.