The Ivomec SR Bolus for Control of <I>Boophilus annulatus</I> (Acari: Ixodidae) on Cattle in South Texas

Abstract

When Hereford heifers infested with Boophilus annulatus (Say) were treated with a single Ivomec SR Bolus, the concentration of ivermectin in the serum of the treated cattle reached a maximum of 8.8 +/- 0.9 ppb at 2 wk posttreatment. The single bolus treatment resulted in 84.4% control of standard engorging B. annulatus females on treated cattle over the 20-wk trial. Although fewer engorged ticks were collected from the sentinel heifers exposed in the treated pasture than those in the control pasture at weeks 4, 10, and 16 posttreatment, none of the differences was statistically significant. Each exposure of sentinel cattle found free-living ticks in both the treated and control pastures, indicating the infestation was not eliminated by the treatment. When the trial was repeated using two Ivomec SR Boluses/heifer, the concentration of ivermectin in the serum of the treated cattle reached a maximum level of 31.2 +/- 3.9 ppb at week 13 posttreatment. The use of two boluses/heifer resulted in 99.6% control of standard engorging B. annulatus females over the 20-wk trial. No ticks were found on sentinels placed in the treated pasture after week 9 posttreatment, an indication that the treatment had eliminated the free-living population in the treated pasture. From these studies, we conclude that a single Ivomec SR Bolus is incapable of sufficient control of B. annulatus to meet the rigid requirements of the Cattle Fever Tick Eradication Program in South Texas. Although two boluses per animal did eliminate the ticks from treated heifers and the pasture they were in, the treatment would not be sufficiently efficacious for mature cattle (>400 kg) for it to be useful in the program.

Impact of ivermectin on the ultrastructure of the testis of Argas (Persicargas) persicus (Ixodoidea: Argasidae)

“…IVM affects gamma-aminobutyric acid (GABA) or glutamate inhibition in Drosophila melanogaster (Cully et al 1996), Ascaris suum (Brownlee et al 1997) and Caenorhabditis elegans (Dent et al 1997). Knowledge of the impact of IVM on ticks was mainly confined to biological parameters after subcutaneous inoculation of hard ticks (Centurier and Barth 1980;Morsy and Haridy 2000), although sustained release bolus (Miller et al 2001) or pour-on (Davey and George 2002) formulations are recommended for control. The histopathological effects of IVM against acarine organs remain unknown.…”

Efficacy of the Ivomec SR Bolus for Control of Horn Flies (Diptera: Muscidae) on Cattle in South Texas

“…Although treatment with two Ivomec SR boluses could be expected to provide signiÞcant control of blood-feeding adults for up to 17 wk, such a treatment would not be considered practical. In a recent study, Miller et al (2001) drew similar conclusions with respect to the efÞcacy of the Ivomec SR bolus against Boophilus annulatus (Say). …”

Formas Farmacêuticas De Liberação Modificada Utilizadas Em Ruminantes: Uma Revisão

“…Outro exemplo é o Ivomec ® SR Bolus (Mountain View, CA, EUA), uma bomba osmótica que possui os compartimentos do agente osmótico e do fármaco separados por um êmbolo de cera, o qual foi concebido para administrar o anti-helmíntico ivermectina, para combater parasitas diretamente no rúmen, por um período de até 135 dias (BRAYDEN et al, 2010;MILLER et al, 2001;WRIGHT, 1999). O Panacur ® SR (Hoechst-Roussel, Intervet, Canada) é um dispositivo intraruminal de alta densidade para a liberação controlada de fembendazol, usado na profilaxia e no tratamento de infecções por nematódeos gastrintestinais em bovinos por até quatro meses (ROTHEN-WEINHOLD et al, 2000).…”