Presence and characterization of microplastics in pet blood (dogs and cats): Evidence of environmental contamination

Increasing evidence identifies microplastics (MPs) as ubiquitous environmental contaminants, across marine, terrestrial, and atmospheric ecosystems. Their size and physicochemical properties facilitate widespread distribution and bioavailability, raising increasing concerns regarding their potential impact on animal and human health. Their presence in aquatic organisms (e.g., fish, mussels), marine mammals, and birds is demonstrated but evidence related to dogs and cats are relatively few. The present study investigated, for the first time in living subjects, the presence of MPs in the blood of dogs and cats, aiming as well at characterizing them both quantitatively and qualitatively. Twenty pets (14 dogs and 6 cats), resulting in totally 20 samples of whole blood, were included in the study. MPs were detected in every individual sample analyzed, in both dogs and cats, and statistical analyses performed to compare microplastic abundance, morphology, color distribution, and size characteristics between the two species did not show significant differences, suggesting that dogs and cats are exposed to MPs in a similar way. These findings should not be interpreted as demonstrating equivalent exposure, since individual environmental and lifestyle determinants were not systematically assessed. Additionally, blood is suggested as a promising matrix for MPs biomonitoring. The present results invite to investigate larger cohorts of patients, evaluating any possible correlations between MPs presence/characteristics and state of health or disease, together with any potential correlation with age, sex, breed, species, environment and lifestyle. Such data on pets may contribute both to understand their health risks, and to reinforce their role as sentinels of environmental exposure, providing valuable insights within a One Health framework.