Systemic Effects of Ocular Instillation of 0.4% Ketorolac Trometamol and Luminol‐Based Detection of Fecal Occult Blood in Healthy Cats

OBJECTIVES: To assess the impact of thrice-daily instillation of 0.4% ketorolac trometamol (KT) over 15 days on blood count, serum biochemistry, and urinalysis in healthy cats. Additionally, we tested the efficacy of luminol to detect fecal occult blood (FOB) in feces. METHODS: A placebo-controlled, randomized study was conducted with 24 healthy cats. In 12 cats, each eye received either 40 μL of KT or saline (S) every 8 h for 15 days. An additional 12 cats received saline in both eyes and served as controls (S). Baseline blood count, serum biochemical analysis, urinalysis, and FOB testing were performed before the study and after each 15-day treatment period. RESULTS: Baseline blood count, serum biochemistry, and urinary values were within reference limits for both treatments. By day 15, increased cholesterol (p = 0.002) and decreased potassium (p = 0.01) levels were observed in KT. Despite these changes, all measurements remained within reference limits, except for ALT, which significantly increased at day 15 in KT when compared to baseline (p = 0.01) and S (p = 0.003). At baseline, all fecal samples from KT and S tested negative for FOB. By day 15, 10 of 12 KT samples tested positive for FOB (p < 0.0001). CONCLUSION: This study demonstrates that thrice-daily instillation of KT for 15 days induces a subclinical hepatocellular injury and gastrointestinal bleeding, with potential effects on potassium levels in healthy cats. Luminol proved to be a reliable test for detecting fecal occult blood in the feces of healthy cats.