Field evaluation of a mixture of albendazole sulphoxide and levamisole against Ostertagia and Trichostrongylus spp in sheep

Abstract

The efficacy of a mixture of albendazole sulphoxide and levamisole, 3.6 and 8.25 mg/kg respectively, at single and double dose rates, was compared with the recommended dose rate of each anthelmintic alone. The comparison was conducted on groups of 6 to 14-week-old lambs on 22 farms, 16 of which had evidence of multiple resistance to benzimidazole and levamisole. A single dose of the mixture reduced mean egg counts by 95% on half the farms with multiple resistance and on all the remaining farms. Consequently, the mixture should be included in an assessment of effective anthelmintics on farms to determine its value for nematode control. A double dose rate of mixture was effective on all but 4 farms. Reductions caused by the mixture were due to the additive actions of the drugs on 18 of 22 farms; synergistic action was noted on only 3 farms. It was concluded that the mixture of albendazole sulphoxide and levamisole offered many farmers an effective anthelmintic for use in preventive control programs. Recommendations for such programs include annual rotation of effective anthelmintics as a means of delaying selection for drug resistance.

Efficacy of a morantel–abamectin combination for the treatment of resistant ascarids in foals

“…These findings indicate that combination anthelmintics can potentially provide control when resistance to one of the constitutive drugs is present in Parascaris populations. There is evidence that combinations are effective for control of nematodes with AR in ruminants and slow the development of AR, especially when introduced before resistance is evident …”

“…5 These findings indicate that combination anthelmintics can potentially provide control when resistance to one of the constitutive drugs is present in Parascaris populations. There is evidence that combinations are effective for control of nematodes with AR in ruminants 7,11,12,15 and slow the development of AR, especially when introduced before resistance is evident. 8,[10][11][12] Anthelmintic combinations delay resistance by reducing the number of resistant genotypes that survive treatment, as multiple resistance alleles must be present for parasite survival, resulting in greater dilution by unselected susceptible genotypes in the population.…”

“…Although prudent use of anthelmintics is advocated, there are few other control options and so anthelmintic use is necessary to prevent disease. In ruminant grazing systems, the use of combinations of anthelmintics with a similar spectrum of activity and different mechanisms of action is a strategy for achieving sustainable parasite control . Combination anthelmintics are used to slow the development and spread of AR and enable parasite control in the presence of pre‐existing single or multiple drug resistance .…”

“…In ruminant grazing systems, the use of combinations of anthelmintics with a similar spectrum of activity and different mechanisms of action is a strategy for achieving sustainable parasite control. [7][8][9][10][11] Combination anthelmintics are used to slow the development and spread of AR and enable parasite control in the presence of pre-existing single or multiple drug resistance. [8][9][10][11][12] The use of combination anthelmintics has the potential to control equine parasites when AR is present.…”

Field efficacy and safety of an oral formulation of the novel combination anthelmintic, derquantel-abamectin, in sheep in New Zealand

“…Combination anthelmintics have been shown to be effective against populations of gastrointestinal nematodes that have developed resistance to single-active anthelmintics, thus extending the useful life of existing classes (McKenna 1990; Anderson et al 1991a b). The potential for combinations to delay or slow the development of resistance to their individual components has also been proposed (Anderson et al 1988; Smith 1990; Barnes et al 1995; Dobson et al 2001; Leathwick et al 2009).…”