Environmental Exposures and Canine Bladder Cancer: A Case Control Study Using Silicone Passive Samplers

Pet dogs offer valuable models for studying environmental impacts on human health due to shared environments and a shorter latency period for cancer development. We assessed environmental chemical exposures in a case-control study involving dogs at high risk of urothelial carcinoma, identified by a BRAF V595E mutation in urinary epithelial cells. Cases (n = 25) exhibited low-level BRAF mutations, while controls (n = 76) were matched dogs without the mutation. Each dog wore a silicone sampler for five continuous days to assess environmental exposures. Silicone samplers were analyzed using targeted and suspect screening (i.e., nontargeted) methods. Of 115 targeted chemicals, 39 were detected in >50% of samplers, with cases showing significantly higher levels (2-3×) of BDE-47, BDE-99, anthracene, and benzyl butyl phthalate (p < 0.05). Suspect screening identified that cases were exposed to more chemicals, often at higher exposure levels. For example, cases had significantly higher levels of 25 chemical features compared to controls (p < 0.05). This is the largest study to date to quantify such a wide breadth of contaminant exposure levels associated with canine urothelial carcinoma and the first to assess a population with subclinical disease, highlighting pet dogs as models to study environmental contributions to cancer risk, advancing both human and veterinary health.