Just as it might not be the best idea to give a newborn baby an adult-sized dose of ibuprofen, it’s not always the best idea to give a neonatal foal an adult dose of medications.

"Neonatal foals have different pharmacokinetics compared to adults, which may lead to accumulation of drugs and adverse effects when adult dosing regimens are used," explained Elsbeth Swain, DVM, Dipl. ACVIM.

But veterinarians still don’t know exactly how all the drugs they commonly use to treat neonates interact with their young bodies. To that end, Swain and colleagues at the University of California, Davis, recently evaluated the pharmacokinetics (how the drug levels are processed and maintained in the body) of metronidazole, an antimicrobial drug often used to treat diarrhea, in neonatal foals. She presented the results of the study at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.

Swain, now a faculty member at Colorado State University College of Veterinary Medicine & Biomedical Sciences Equine Field Service, and her team set out to evaluate metronidazole’s pharmacokinetics in healthy foals, aged 1 to 2.5 days, when administered as a single intravenous (IV) or intragastric (IG, administered orally) dose. The team separated 12 neonates into two groups; one group received 15 mg/kg of metronidazole IV and the other received the same dose orally. The researchers monitored plasma metronidazole concentrations regularly. Additionally, the team repeated the test on the foals in the IV group when they reached 10 to 12 days of age to evaluate maturational differences