The prevalence of hyperthyroidism in domestic cats has skyrocketed since it was first diagnosed in 1979—in 2014 the disease affected 1 in 10 cats over the age of 10 in the US, according to the American Association of Feline Practitioners. New research led by Kim Anderson at Oregon State University points to a possible cause: exposure to flame retardants commonly found in home furniture (Environ. Sci. Technol. 2019, DOI:10.1021/acs.est.9b02226). The introduction of flame retardants in the home coincided with the first cases of feline hyperthyroidism in the late 1970s, so Anderson’s group decided to study whether feline exposure is associated with the disease. Pet-owning volunteers affixed silicone pet tags to their feline friends’ collars for a week before returning them for gas chromatography/mass spectrometry analysis. Similar studies have used silicone wristbands to measure chemical exposure in people; this was the first study in companion animals. Among the 21 components detected, hyperthyroidism was most strongly correlated with exposure to tris(1,3-dichloro-2-isopropyl) phosphate (TDCIPP). Cats whose owners used air fresheners at least monthly had the highest exposures. And differences in TDCIPP were linked to specific behaviors, such as a preference for lounging on upholstered furniture, which resulted in higher TDCIPP exposure. Concerned pet owners should consider using furniture covers and reducing air freshener use, Anderson suggests.