Comparison of As, Cd, Cu, Fe, and Pb levels in dry cat foods containing different protein sources (poultry, fish, red meat) and in cats consuming these diets

Heavy metals are an important source of environmental contamination and can enter the pet food chain through animal-derived protein ingredients and drinking water. Owing to their obligate carnivorous nature and strong reliance on animal-based proteins, cats may be exposed to diet-related potentially toxic metals. It was aimed to compare arsenic, cadmium, copper, iron, and lead concentrations in commercial dry cat foods (n = 300) formulated with different primary protein sources (poultry, fish, and red meat), and to investigate potential toxic effects in relation to protein source and duration of dietary exposure. Cats (n = 750) were grouped according to dietary protein source and feeding duration. Heavy metal concentrations were determined in cat foods, household drinking water, serum, and hair samples using ICP-OES. Cadmium concentrations were significantly higher in fish- and red meat–based diets compared with poultry-based diets; copper and iron concentrations were higher in poultry-based diets. All measured metal concentrations remained below established regulatory limits in diets. In biological samples, no consistent accumulation was observed according to protein source or feeding duration. Cats fed poultry-based diets exhibited higher blood copper and iron concentrations and lower blood lead levels compared with other groups; however, all values remained within physiological reference ranges. Hair metal concentrations did not differ significantly among dietary groups. Heavy metal concentrations measured in the evaluated diets were generally within suggested guidelines. Although copper concentrations exceeded recommended limits by FEDIAF in some diets, this wasn’t associated with clinically relevant accumulation in cats. Given the observational and cross-sectional nature of the study, these findings should be interpreted cautiously and do not exclude the possibility of long-term accumulation or risk associated with chronic exposure.