Drugs have been compounded for veterinary practice for many years because it has been necessary in the course of routine practice. However, regulations and compliance policy guidelines (CPGs) should be recognized. A new CPG issued in July 2003 listed the current Food and Drug Administration (FDA) limitations on compounding for veterinary medicine. To summarize the guideline: drugs must not be compounded from bulk substances, and the compounding must not constitute manufacture of a new animal drug. Drug compounding on a case-by-case basis is allowed under the CPG. However, veterinarians and pharmacists must be aware of potential incompatibilities and practices that may interfere with the drug’s stability, purity, and/or potency.