Efficacy of Eprinomectin and Doramectin Against <I>Amblyomma americanum</I> (Acari: Ixodidae) on Cattle

Abstract

Steers were treated with doramectin or eprinomectin by daily oral capsule for 28 consecutive days. The level of doramectin in the serum of steers treated at 200 microg/kg/d reached a maximum of 104.0 +/- 22.1 ppb at day 21 and declined from 93.3 +/- 20.5 ppb on the final day of treatment to below detectable by day 56. Steers treated at 50 microg/kg/d reached a maximum level of doramectin in the serum of 24.7 +/- 1.2 ppb on day 21 and declined from 24.7 +/- 0.6 ppb on the final day of treatment to less than detectable on day 42. Both doramectin dosages provided 100% control of estimated larvae (EL) of Amblyomma americanum (L.) (Acari: Ixodidae) throughout the 28-d treatment period. Daily oral treatment with eprinomectin at a dosage of 200 microg/kg for 28 consecutive days produced a maximum concentration in the serum of 41.6 +/- 11.0 ppb at day 14. On the final day of eprinomectin treatment, the serum concentration was 38.3 +/- 5.9 ppb. Seven days later at day 35, eprinomectin was not detectable in the serum. For steers treated at 50 microg/kg/d for 28 consecutive days, the serum level of eprinomectin reached a maximum of 10.0 +/- 3.0 ppb on day 28 and was undetectable on day 35. Both eprinomectin dosages provided complete control of EL of A. americanum during the 28-d treatment period. Because eprinomectin is efficacious against A. americanum at lower serum levels in cattle and is eliminated from the serum at a more rapid rate than either doramectin or ivermectin, it provides advantages for use in applications such as the medicated bait for control of ticks on white-tailed deer and could have potential for use in the Cattle Fever Tick Eradication Program.

A Review on the Toxicity and Non-Target Effects of Macrocyclic Lactones in Terrestrial and Aquatic Environments

“…Eprinomectin (EPR) and doramectin (DOR) have been registered against all stages of the major gastrointestinal nematodes, lungworm, as well as lice, horn fly, ticks and mange mites of cattle [227]. Both of these MLs have significant persistent activity against a range of important nematodes.…”

Efficacy of abamectin against the fowl tick, Argas (Persicargas) persicus (Oken, 1818) (Ixodoidea: Argasidae)

“…The effect of avermectins against ticks using different routes of application was considerably studied (Davey et al 2010;Lohmeyer et al 2009;Sajid et al 2009;Marzouk et al 2004;Montasser 2004). However, studies concerned with the effect of abamectin against ticks are scarce.…”

A blood digestion scoring method for poultry red mites, Dermanyssus gallinae

“…To assess the applicability of blood digestion scoring method in the efficacy study, the effects of doramectin on the blood digestion of PRMs was evaluated. Doramectin was chosen based on these considerations, as an avermectin, doramectin shows good efficacy against a variety of parasites, such as mites, ticks and nematodes (Lohmeyer et al ., 2009; Edmonds et al ., 2018; Larroza et al ., 2020; Mauger et al ., 2022), and its effects on the blood digestion of PRMs was not reported. Doramectin (with a purity of 95%, purchased from Nanning Guangtai Agricultural Co. Ltd, China) was dissolved in an ethanol/PBS/Tween 80 mixture at a 33:66:1 ratio (v/v) to formulate a 2 mg mL −1 solution.…”