Efficacy and economic analysis of two treatment regimens using toltrazuril in lambs naturally infected with Eimeria spp. on pasture

Abstract

This study evaluated the efficacy and the economic viability of two anticoccidial treatment regimens tested in lambs naturally exposed to Eimeria spp. re-infections in a grazing system during a 140-day period. Twenty-four suckling lambs were distributed into three groups based on the individual count of oocysts per gram of feces (OPG) and body weight. Animals were treated with toltrazuril 5% (20 mg/kg) at 14- (GI) or 21-day (GII) intervals, and GIII was kept as untreated control. A cost-benefit analysis of each treatment regimen was calculated. Additionally, economic analysis was performed on four hypothetical scenarios, in which lambs could be having 10, 25, 50, or 85% decrease in their expected body weight gain due to clinical. Efficacy of toltrazuril against Eimeria spp. was 96.9-99.9% (GI) and 74.2-99.9% (GII). E. ovinoidalis was most frequently identified, but no clinical signs of coccidiosis were observed in lambs. There were no differences in weight gain among the groups. The cost of treatment per lamb was $13.09 (GI) and $7.83 (GII). The estimation model showed that the cost-benefit ratio favored treatment with toltrazuril when lambs fail to gain weight. In the studied flock, the break-even point for toltrazuril administered at 14-day intervals was reached with 85% decrease in mean weight gain. In conclusion, toltrazuril can be used at 14-day intervals to control Eimeria spp. (re)-infection in lambs raised on pasture. This treatment regimen was not economically feasible for subclinical coccidiosis; however, it may be feasible when used to prevent weight loss caused by clinical coccidiosis.

Field evaluation of anticoccidial efficacy: A novel approach demonstrates reduced efficacy of toltrazuril against ovine Eimeria spp. in Norway

“…The classification thresholds used in our study were based on the figures of 90% and 95% used by Geurden et al (2015) and Peña-Espinoza et al (2016) in anthelmintic studies, as there is currently no published target efficacy available for toltrazuril. The same classification targets were used by de Souza Rodrigues et al (2017) who investigated the efficacy of different toltrazuril treatment strategies in Brazil. However, we note that although these figures seem reasonable in the absence of alternatives, there is no specific evidence to support the direct translation of 90% and 95% efficacy targets from their intended context of estimating the arithmetic mean efficacy of anthelmintic compounds against nematodes to the quite different context of estimating the geometric mean efficacy of anticoccidial compounds.…”

Controlled efficacy trial confirming toltrazuril resistance in a field isolate of ovine Eimeria spp.

“…Although the initial efficacy values have not been provided for toltrazuril by the manufacturer, several studies have investigated its effect on oocyst excretion. For example, its efficacy has been found to be 96.9-99.9% in the period from 7 to 98 days after first treatment, in a study in which the lambs were treated every 14 days [52]. Other studies have shown toltrazuril efficacies [either provided in the publication or calculated as 1-(mean OPG treated group)/(mean OPG control group) from data in the publication] ranging from 90.0 to 100.0% in the period from two to three weeks after treatment [13,18,19,[53][54][55][56].…”

Ovine Eimeria infections in southern Brazil – prevalence and risk factors

“…This silent illness is hard to detect and expensive to treat. Rodrigues et al (2017) showed that subclinical coccidiosis treatment is economically unfeasible; however, it may be viable when used to prevent weight loss from clinical coccidiosis.…”

“…Coccidiosis has considerable economic importance, causing decreases in productivity, low growth performance, diarrhea, and mortality (Khodakaram-Tafti & Hashemnia, 2017). Furthermore, treatment costs are high and are not always economically viable, especially in subclinical infections (Rodrigues et al, 2017). Many Eimeria infections in sheep are asymptomatic; however, more frequently in lambs, some species have been associated with diarrhea and stunted growth (Chartier & Paraud, 2012).…”

“…If treatment is not undertaken, intense dehydration can lead to death. The severity of infection is a result of multiple conditions, including decreased host immunity, high parasite load, management and sanitary conditions, animal density, breed susceptibility, and presence of pathogenic Eimeria species (Khodakaram-Tafti & Hashemnia, 2017; Rodrigues et al, 2017).…”