Environmental Chemical Exposures in Boxer Dogs With Multicentric Lymphoma

Multicentric lymphoma (ML) in dogs has similar clinical features to human non-Hodgkin lymphoma (NHL). NHL has been linked to herbicides and volatile organic compounds (VOCs), direct exposures to these chemicals have not been evaluated in ML.

ML in pet dogs was associated with herbicide and VOC exposures.

Twenty pet boxer dogs with ML and 20 unaffected pet boxer dogs enrolled across the United States between 2021 and 2024.

Prospective case-control study. Dog owners completed an environmental questionnaire and submitted dog urine, drinking water, and household air samples for analysis of the herbicides 2,4-D, glyphosate, and atrazine and the VOCs benzene, 1,3 butadiene, and trichloroethylene. Area Deprivation Indices (ADI) and USDA Rural-Urban Continuum Codes (RUCC) were assigned to all dogs based on home address.

Boxers with ML were more likely to live in more urban counties (median RUCC 1, range 1-6 for cases, vs. median 2, range 1-8 for controls; p = 0.032). Urinary concentrations of the benzene metabolite S-phenylmercapturic acid (PHMA) were higher in dogs with ML (median 1.03 ng/mg creat, range 0.00-1.53) compared to control dogs (0.54 ng/mg creat, range 0.09-4.73; p = 0.031). Odds ratios for exposure to the benzene metabolite MUCA were higher in cases vs. controls, even when controlled for urbanicity (OR 1.01, 95% CI 1.00-1.02; p = 0.035).

ML in boxers might be associated with benzene exposures. If this association is causative, indoor benzene exposures could be remediated with activated carbon air filtration and certain house plants.