Veterinarians and owners are increasingly reaching for compounded famciclovir for treatment of feline herpesvirus. Unlike their FDA-approved counterparts, compounded drugs seldom undergo any quality control testing. In fact, many compounded formulations are ineffective according to recent veterinary literature. For famciclovir, such erroneous formulations would mean prolonged clinical signs, increased shedding and spread of virus, and promotion of antiviral resistance. Using Famvir® as the control, we hypothesize that compounded formulations of famciclovir will have decreased accuracy (drug content), decreased stability (fast degradation), and decreased precision (high variability). This will be verified by analyzing compounded famciclovir at different doses, from different pharmacies and at different times. Results of this study will enable veterinarians and owners to make informed decisions when prescribing famciclovir-ensuring cats only receive effective treatments.