Drug Interaction Assessment in Multidrug Protocols Used for Canine Distemper Management in Lagos State

Canine distemper remains a devastating viral disease in unvaccinated dog populations across Nigerian cities, including Lagos State, South West Nigeria. The multisystemic nature of the disease necessitates complex supportive treatment regimens involving multiple drug classes simultaneously, creating significant potential for clinically relevant drug interactions. This study systematically assessed the drug interaction potential of multidrug treatment protocols used for canine distemper management at 20 veterinary hospitals in Lagos. Treatment records from 80 confirmed distemper cases over a two-year period were reviewed. Drugs used in each case were extracted and potential pharmacokinetic and pharmacodynamic interactions were assessed using established drug interaction databases and published veterinary literature. A mean of 5.4 drugs per case was recorded in the reviewed protocols. The most commonly used drugs were prednisolone, phenobarbitone, amoxicillin-clavulanate, metronidazole, and vitamin B complex. Potentially significant pharmacokinetic interactions were identified in 48.8 percent of cases, with the most common being phenobarbitone-mediated induction of prednisolone metabolism, potentially reducing glucocorticoid efficacy. Pharmacodynamic interactions with additive central nervous system depression risk were identified in 27.5 percent of protocols involving concurrent diazepam and antihistamine use. Actual adverse outcomes attributable to identified interactions were documented in 11.3 percent of affected cases. These findings highlight the importance of pharmacological knowledge in managing canine distemper and recommend the development of standardised, interaction-reviewed treatment protocols at Nigerian veterinary hospitals. Keywords: drug interactions, canine distemper, polypharmacy, Lagos, pharmacokinetics.