Ketoprofen use in dogs is uncommon in jurisdictions where greyhounds are raced but with lower costs and food safety residues it is selected for the increased anti-inflammatory use in farm animals. Feeding meat to racing greyhounds is challenging for greyhound trainers and regulators, both with residues in ‘knackery’/Animal By Product meat, and no food safety residue limit in the U.K. and Ireland for food. Stringent levels of detection used in greyhound racing risks exposing trainers to unknowing liability for ketoprofen.
With limited data to manage this risk, ketoprofen and metabolite, 2-[3-(alpha-hydroxy benzyl)phenyl] propanoic acid, elimination in plasma and urine was assessed in 6 greyhounds for 14 days after IV administration of 1 mg/kg. Plasma elimination for both parent and metabolite fitted to a 3 compartmental model, this reflected in urine.
Effective plasma concentration (EPC) was 837 ng/mL, irrelevant plasma concentration (IPC) 2 ng/mL, irrelevant urine concentration (IUC) 5 ng/mL. Detection Time (DT) was 114 hours in plasma and 120 hours in urine. Initial urine screening limits were 5 ng/mL for parent, and 50 ng/mL for the metabolite, with 2 ng/mL for plasma .
Kidney and muscle food safety residue levels were assessed to compare exposure via feeding to greyhounds to exposure via treatment. For higher kidney residue levels plasma and urine levels were above the proposed IPC and IUC while ketoprofen metabolite urine levels were below the screening limit of 50 ng/ml. Therefore ketoprofen plasma and urine screening limits were raised to 5 and 10 ng/mL, respectively, as part of the secondary risk management of the primary risk from exposure to meat. These adjusted levels have now been set as screening limits (or residue limits), harmonised across Britain and Australasia, with a 144 hours DT.