Abstract
This study aimed to assess stress in indoor and free-ranging domestic cats by measuring biomarkers (serotonin, cortisol, dopamine) in serum and urine, along with urinary hippuric acid levels, and to examine their correlation with exposure to industrial substances, particularly toluene-containing materials. A total of 244 cats underwent physical and laboratory assessments, including anamnesis, physical examination, laboratory analyses (urine analysis, urine sediment analysis, urine bacterial culture, venous blood gas analysis, complete blood count (CBC), serum biochemistry), and abdominal ultrasonographic examination. After applying inclusion/exclusion criteria, 16 cats were categorized into two groups: Free-ranging (n = 8) and Indoor (n = 8). Serum and urine serotonin, cortisol, dopamine, and urinary hippuric acid concentrations were measured to assess exposure to indoor materials. Indoor cats had a higher respiratory rate and significantly greater bladder wall thickness (0.28 ± 0.07 cm vs. 0.19 ± 0.02 cm, p = 0.002). Urine pH was lower in indoor cats, and hippuric acid crystals were found in their urine sediment. Serum serotonin levels were lower in free-ranging cats (p = 0.006), while urinary serotonin (p = 0.005), cortisol (p = 0.012), dopamine (p = 0.003), and hippuric acid (p = 0.033) levels were higher in indoor cats. The findings suggest that indoor confinement may be associated with increased physiological stress and greater exposure to toluene-containing materials, which could potentially contribute to stress-related conditions and elevate the risk of toluene-associated effects.