Enrofloxacin, an antimicrobial agent used to treat bacterial diseases is well tolerated by cats at recommended dosage (5 mg/kg). To investigate the tolerance of high-dose of the Hipralona Enro-I^® (5% enrofloxacin solution) in cats, 28 urban cats (11 males and 17 females) between the weight of 1.3 and 2.4 kg were randomly assigned to a control group (n=4) and three treatment groups (n=8). Each treatment groups were injected low-dose enrofloxacin (5 mg/kg, IM), high-dose enrofloxacin (15 mg/kg, IM), and very high-dose enrofloxacin (25 mg/kg, IM) once daily for seven consecutive days. Blood samples were collected from jugular vein before injection of enrofloxacin in the hind limb muscles of cats as self-control, and at 3^rd, 7^th, 14^th, and 21^st days after first drug injection. Samples were tested for various hematological and serum biochemical parameters. The systemic tolerance during experiment was investigated via monitoring of behavior and general physical examination. Hematological and serum biochemical parameters were not significantly different between groups. In addition, there was no statistically difference between various sampling days for any treatment group in each parameter. Furthermore, there was no change in the behavior and the general health condition of cats in the control and the three experimental groups. As serum biochemical indications of hepatotoxication and nephrotoxication were not observed. It was concluded that muscular injection of enrofloxacin in doses up to 25 mg/kg (5ED₅₀) for seven consecutive days was tolerated by cats.

Key words: Biochemical parameters, Cat, Enrofloxacin, Hematological parameters, Intramuscular injection