Nematode burdens of pastured cattle treated once at turnout with eprinomectin extended-release injection

Abstract

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was evaluated against infections with third-stage larvae or eggs of gastrointestinal and pulmonary nematodes in cattle under 120-day natural challenge conditions in a series of five studies conducted in the USA (three studies) and in Europe (two studies). For each study, 30 nematode-free (four studies) or 30 cattle harboring naturally acquired nematode infections (one study) were included. The cattle were of various breeds or crosses, weighed 107.5-273 kg prior to treatment and aged approximately 4-11 months. For each study, animals were blocked based on pre-treatment bodyweight and then randomly allocated to treatment: ERI vehicle (control) at 1 mL/50 kg bodyweight or Eprinomectin 5% (w/v) ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg) for a total of 15 and 15 animals in each group. Treatments were administered once on Day 0 by subcutaneous injection in front of the shoulder. In each study, all animals grazed one naturally contaminated pasture for 120 days. At regular intervals during the studies, fecal samples from all cattle were examined for nematode egg and larval counts. In four studies pairs of tracer cattle were used to monitor pasture infectivity at 28-day intervals before and/or during the grazing period. All calves were weighed before turnout onto pasture and at regular intervals until housing on Day 120. For parasite recovery, all study animals were humanely euthanized 27-30 days after removal from pasture. Cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer strongylid eggs (≤1 egg per gram; egg count reduction≥94%) than the control cattle and zero lungworm larvae at each post-treatment time point. At euthanasia, cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer of the following nematodes than the ERI vehicle-treated (control) cattle with overall reduction of nematode counts by >92%: Dictyocaulus viviparus (adults and fourth-stage larvae (L4), Bunostomum phlebotomum, Cooperia curticei, Cooperia oncophora, Cooperia punctata, Cooperia surnabada, Cooperia spp. inhibited L4, Haemonchus contortus, Haemonchus placei, Haemonchus spp. inhibited L4, Nematodirus helvetianus, Nematodirus spp. inhibited L4, Oesophagostomum radiatum, Oesophagostomum spp. inhibited L4, Ostertagia leptospicularis, Ostertagia lyrata, Ostertagia ostertagi, Ostertagia spp. inhibited L4, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus spp. inhibited L4, Trichuris discolor, and Trichuris ovis. Over the 120-day grazing period, Eprinomectin ERI-treated cattle gained between 4.8 kg and 31 kg more weight than the controls. This weight gain advantage was significant (p<0.05) in three studies. All animals accepted the treatment well. No adverse reaction to treatment was observed in any animal in any study.

56 The efficacy of extended-release eprinomectin for the reduction of horn flies, face flies, and fecal egg counts of parasitic nematodes in replacement beef heifers

“…In order to increase protection against nematodes and ectoparasites while lowering the amount of injections needed, the animal health company Merial, created an extended-release injectable cattle dewormer Long Range TM (eprinomectin) (Boehringer, 2012). One dose provides 100 to 150 days of parasite control which is enough time to break the parasite life cycle and reduce egg populations in pastures (Rehbein, 2013). Extended-release eprinomectin is a subcutaneous injection to the neck which injects a 5% solution of eprinomectin that is dispensed at a rate of 1 mg/kg body weight (Forbes, 2013).…”

“…Past studies have proven that eprinomectin extended-release injectabe (ERI) reduced the egg count by >94% and reduced the nematode counts by >92% in treated cattle (Rehbein, 2013).…”

“…Eprinomectin has been proven to have a three times greater efficacy against helminth control compared to ivermectin as shown in dose titration studies (Rehbein, 2013;Shoop et al,1996;Shoop and Soll, 2002). Extended-release eprinomectin is categorized as a broad spectrum endectocide due to the fact that it has been proven to be effective against the eradication of endoparasite and ectoparasite populations (Shoop, 1996.…”

A critical review and meta-analysis of the magnitude of the effect of anthelmintic use on stocker calf production parameters in Northern US States

“…459 did not meet the predetermined eligibly criteria and 53 articles were retrieved for further assessment. After evaluation of the full text, only 9 manuscripts and 23 studies were relevant to the stocker review (Ballweber et al, 1997;Cleale et al, 2004;Epperson et al, 2001;Ferguson et al, 1971;Kunkle et al, 2013;Mertz et al, 2005;Rehbein et al, 2013;Skogerboe et al, 2000;Smith and Woolfolk, 1973) Of the 23 studies, only 14 were suitable for meta-analysis; however, all studies are summarized in tables.…”

“…ADG was reported in seven manuscripts (Ballweber et al, 1997;Cleale et al, 2004;Epperson et al, 2001;Ferguson et al, 1971;Mertz et al, 2005;Skogerboe et al, 2000;Smith and Woolfolk, 1973) with 20 separate studies. Weight gain was reported in three manuscripts with eight studies (Ferguson et al, 1971;Kunkle et al, 2013;Rehbein et al, 2013).…”