Compounding, the practice of changing the preparation, strength, or even flavor of a drug to meet a particular therapeutic requirement for a specific patient, is a long-established practice in veterinary medicine. Especially before major pharmaceutical companies dove into the veterinary arena, practitioners commonly mixed preparations from human drugs into dosages or forms that suited their equine patients. Over time, as veterinary medicine has become a busier and more specialized field, the drug compounding role has shifted to specific pharmacies.

As a veterinarian, I’ve used compounding pharmacies to formulate a variety of medications for my patients and consider myself fairly well-informed on the basics of veterinary drugs. Yet, prior to my recent visit to the University of California, Davis, California Animal Health and Food Safety Laboratories, if someone had asked me to explain the rules around drug compounding, or any of the issues or questions at hand, I’d have been lost.

Talking with Scott Stanley, PhD, an associate professor of veterinary medicine at the university, proved enlightening in many ways. Stanley, who has investigated a number of compounded drug formulations and published analyses of some of these drugs, succinctly sums up why drug compounding seems to hit the news every few years: Because there’s some sort of catastrophe, he says, citing for example the 2009 incident in which 21 polo ponies died due to a misformulation of a compounded supplement. Or, more recently, drug compounding hit the human health news after a contaminated batch of methyl prendisolone resulted in lethal cases of fungal meningitis.