Evidence linking ambient air pollution to domestic animal health outcomes: a scoping review.

Overview

• This scoping review summarizes current research on the relationship between ambient air pollution and health outcomes in domestic animals, identifying existing evidence and gaps to guide future studies.

Introduction and Objective

• Air pollution is a significant global health issue that is expected to worsen over time.
• While much is known about air pollution’s impact on human health, its effects on domestic animals are not well understood.
• The objective of the review was to systematically collect and synthesize existing evidence on how ambient air pollutants affect the health of domestic animals.
• Additionally, the review aimed to identify research gaps to inform future investigations.

Methodology

• A scoping review methodology was employed, following the Arksey and O’Malley framework and the PRISMA-ScR guidelines, which are standardized approaches for conducting and reporting scoping reviews.
• Two databases, PubMed and Web of Science, were searched on August 15, 2024, using terms related to domestic animals, air pollutants, and potential health outcomes.
• Inclusion criteria: studies examining associations between ambient (outdoor) air pollution exposure and health outcomes in domestic animals.
• Exclusion criteria: studies focusing on indoor air quality and experimental exposure studies, as the focus was on real-world ambient air pollution effects.
• Results were synthesized descriptively and narratively, rather than through meta-analysis, reflecting heterogeneity in study designs and outcomes.

Findings – Study Characteristics and Species Studied

• A total of 29 studies met inclusion criteria.
• Species examined included dogs, horses, cattle, sheep, and goats.
• This diversity reflects common domestic animals exposed to ambient air pollution in various settings.

Health Outcomes Assessed

• The studies investigated a broad range of health outcomes, including:
• Cardiopulmonary: effects on the heart and lungs, such as respiratory diseases or cardiovascular stress.
• Neurologic: nervous system effects, potentially including behavioral or cognitive impacts.
• Ophthalmologic: eye-related health outcomes.
• Immunologic: immune system function and related responses.
• Metabolic: effects on metabolism and related physiological processes.
• Reproductive: impacts on fertility, pregnancy outcomes, and offspring health.
• Behavioral: changes in animal behavior potentially linked to pollution exposure.
• Performance and production: effects on athletic performance or agricultural productivity.
• Mortality: impacts on survival rates.

Key Insights and Comparisons with Human Health

• The evidence showed parallels to known human health effects, especially regarding respiratory and neurological outcomes linked to air pollution.
• Notably, cardiovascular and reproductive health outcomes were less frequently studied in animals compared to humans.
• This suggests potential under-exploration of important health effects in domestic animals.

Trends and Implications for Veterinary Medicine

• Recent years have seen an increase in research publications on air pollution and domestic animal health.
• This growing body of work reflects heightened awareness of air pollution as a contributor to animal disease and wellness concerns.
• Veterinarians are increasingly facing inquiries about how poor air quality may affect animal health.
• The review consolidates existing knowledge, highlighting vulnerable animal populations and recognizing air pollution as an emerging health risk.
• Expanding research will help veterinarians better identify pollution-related health issues and advise on mitigation strategies.

Conclusions and Recommendations

• The review provides a foundational synthesis of how ambient air pollution impacts domestic animal health, including multiple organ systems and functions.
• It emphasizes the need for further research, especially in understudied areas like cardiovascular and reproductive outcomes.
• Enhanced understanding will support veterinary professionals and animal owners in responding effectively to air pollution challenges.
• This work encourages interdisciplinary collaboration to protect animal health in environments affected by air pollution.