Reindeer (Rangifer tarandus tarandus) are exposed to the pathogenic parasitic nematode Elaphostrongylus rangiferi
during grazing. The severity of disease is dose-dependent. Prophylactic anthelmintic treatment is needed to
improve animal health and reindeer herding sustainability. Herds are traditionally only gathered once during the
summer, requiring a drug with a persistent effect. In this study we investigated the suitability of long-acting
eprinomectin, given as a single subcutaneous injection at 1 mg/kg bodyweight in adult reindeer and calves.
Plasma and faeces concentrations were determined using ultra-high performance liquid chromatography high
resolution mass spectrometry (UHPLC-HRMS). Plasma concentrations remained above the presumed effect level
of 2 ng/mL for 80 days, demonstrating the drug’s potential. Pharmacokinetic parameters were compared to other
species using allometric scaling. Calves and adults had slightly different profiles. No viable faecal nematode eggs
were detected during treatment. Eprinomectin was measurable in the reindeer faeces up to 100 days, which is of
environmental concern.

Pharmacokinetics of a long-acting subcutaneous eprinomectin injection in semi-domesticated reindeer (Rangifer tarandus tarandus) – A pilot study
Davidson RK, Fæste CK, Uhlig S, Tukun FL, Lian H, Solvang HA, Torvaldsen R, Folkow LP, Romano JS, Kilvær MV, Holmgren KE, Nymo IH.
Environmetal Toxicology and Pharmacology, Volume 97, January 2023, 104041.