Long-Acting Oxytetracycline–Polyethylene Glycol in Horses: Pharmacokinetics and Tolerance

A long-acting oxytetracycline in polyethylene glycol (PEG) was evaluated in a single dose study at 6.6 mg/kg IV and IM and in a long-term dose study at 20 mg/kg IM q 72 h. Pharmacokinetic results were typical for long-acting oxytetracycline formulation. The intramuscular injections caused local irritation, but oxytetracycline-PEG did not alter microbial flora or cause adverse gastrointestinal effects in any horses. Authors’ addresses: Dept. of Veterinary Physiological Sciences (Dowling) and Dept. of Veterinary Microbiology (Chirino-Trejo), Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Dr., Saskatoon, SK, Canada S7N 5B4. r 1999 AAEP.