Allergic and Atopic Eczema in Humans and Their Animals

Epithelial barrier dysfunction and associated diseases in companion animals: Differences and similarities between humans and animals and research needs

Since the 1960s, more than 350,000 new chemicals have been introduced into the lives of humans and domestic animals. Many of them have become part of modern life and some are affecting nature as pollutants. Yet, our comprehension of their potential health risks for both humans and animals remains partial. The "epithelial barrier theory" suggests that genetic predisposition and exposure to diverse factors damaging the epithelial barriers contribute to the emergence of allergic and autoimmune conditions. Impaired epithelial barriers, microbial dysbiosis, and tissue inflammation have been observed in a high number of mucosal inflammatory, autoimmune and neuropsychiatric diseases, many of which showed increased prevalence in the last decades. Pets, especially cats and dogs, share living spaces with humans and are exposed to household cleaners, personal care products, air pollutants, and microplastics. The utilisation of cosmetic products and food additives for pets is on the rise, unfortunately, accompanied by less rigorous safety regulations than those governing human products. In this review, we explore the implications of disruptions in epithelial barriers on the well-being of companion animals, drawing comparisons with humans, and endeavour to elucidate the spectrum of diseases that afflict them. In addition, future research areas with the interconnectedness of human, animal, and environmental well-being are highlighted in line with the "One Health" concept.

Higher prevalence of seizure activity in a small population of atopic dogs: a retrospective breed- and age-matched study

BACKGROUND

Atopic dermatitis (AD) is considered to be a systemic disease in people shown to have an association with epilepsy. However, so far, no data about the association of epilepsy and atopy have been reported in dogs.

OBJECTIVES

Given the homology between human and canine AD, and the increased incidence of epilepsy in atopic people, we investigated the association between AD and seizure-associated activity in a small canine population.

ANIMALS

We included 34 atopic dogs and 34 breed- and age range-matched nonatopic dogs.

METHODS AND MATERIALS

We investigated the association between canine AD and signs of seizures in a retrospective, breed- and age range-matched, case-controlled study. Dog owners were interviewed using a standardized questionnaire. The presence or absence of signs of seizure activity and possible comorbidities were questioned.

RESULTS

Seven of the 34 atopic dogs also suffered from seizure activity. By contrast, only one dog affected with seizure signs could be identified among the 34 nonatopic dogs. Atopic dermatitis was associated with a higher frequency of seizure activity (McNemar test, P = 0.035; one-sided) and atopic dogs had a higher odds ratio to develop seizures [(95% CI) 7 (0.9-56.9)] compared to the age- and breed-matched nonatopic control group. No other comorbidities were detected.

CONCLUSION AND CLINICAL IMPORTANCE

In our small retrospective study, we observed an increased prevalence of seizure activity in the atopic dog population. Further larger and prospective studies are needed to confirm these results.

Outstanding animal studies in allergy II. From atopic barrier and microbiome to allergen-specific immunotherapy

Purpose of review

Animal studies published within the past 18 months were assessed, focusing on innate and specific immunomodulation, providing knowledge of high translational relevance for human atopic and allergic diseases.

Recent findings

Allergic companion animals represent alternative models, but most studies were done in mice. Atopic dermatitis mouse models were refined by the utilization of cytokines like IL-23 and relevant skin allergens or enzymes. A novel IL-6 reporter mouse allows biomonitoring of inflammation. Both skin pH and the (transferable) microflora have a pivotal role in modulating the skin barrier. The microflora of the gastrointestinal mucosa maintains tolerance to dietary compounds and can be disturbed by antiacid drugs. A key mouse study evidenced that dust from Amish households, but not from Hutterites protected mice against asthma. In studies on subcutaneous and sublingual allergen-specific immunotherapy, much focus was given on delivery and adjuvants, using poly-lacto-co-glycolic particles, CpGs, probiotics or Vitamin D3. The epicutaneous and intralymphatic routes showed promising results in mice and horses in terms of prophylactic and therapeutic allergy treatment.

Summary

In atopic dermatitis, food allergies and asthma, environmental factors, together with the resident microflora and barrier status, decide on sensitization versus tolerance. Also allergen-specific immunotherapy operates with immunomodulatory principles.

Comparing immediate-type food allergy in humans and companion animals-revealing unmet needs

Adverse food reactions occur in human as well as veterinary patients. Systematic comparison may lead to improved recommendations for prevention and treatment in both. In this position paper, we summarize the current knowledge on immediate-type food allergy vs other food adverse reactions in companion animals, and compare this to the human situation. While the prevalence of food allergy in humans has been well studied for some allergens, this remains to be investigated for animal patients, where owner-reported as well as veterinarian-diagnosed food adverse reactions are on the increase. The characteristics of the disease in humans vs dogs, cats, and horses are most often caused by similar, but sometimes species-dependent different pathophysiological mechanisms, prompting the specific clinical symptoms, diagnoses, and treatments. Furthermore, little is known about the allergen molecules causative for type I food allergy in animals, which, like in human patients, could represent predictive biomarkers for risk evaluation. The definite diagnosis of food allergy relies-as in humans-on elimination diet and provocation tests. Besides allergen avoidance in daily practice, novel treatment options and tolerization strategies are underway. Taken together, numerous knowledge gaps were identified in veterinary food allergy, which need to be filled by systematic comparative studies.