The effect of tofacitinib with single and prolonged use on the functional state of the cardiovascular system and the clinical condition of dogs: a pilot study

The aim of the study was to initially evaluate the safety of the drug Tofacvel (tofacitinib), which had not previously been used in veterinary practice, for single and prolonged oral administration in dogs as part of a pilot clinical and functional study analyzing the clinical condition and parameters of electrocardiography.The study was conducted in two stages. At the first stage, five dogs received a single 10-fold therapeutic dose of tofacitinib (5.4 mg/kg) followed by a 3-day observation period. At the second stage, four groups of dogs (males and females; ten animals per group) were administered the drug orally once daily for 60 days at single (1x), twofold (2x), and threefold (3x) daily doses, followed by a 10-day post-treatment observation period. One group served as the control. Clinical condition, body weight, food and water intake, body temperature, and electrocardiographic parameters were evaluated. Single administration of the 10-fold therapeutic dose was not associated with mortality, clinical signs of intoxication, or ECG abnormalities. During repeated administration, 100% survival, stable body weight, preserved appetite, and normal body temperature were observed at all dose levels. At the two-fold and three-fold therapeutic doses, functional ECG changes were detected, including an increased heart rate and decreased R–R interval; however, all parameters remained within physiological reference ranges for dogs.