Testing guidance reissued after wormer resistance reports
“The best approach to prevent wormer resistance is to evaluate and implement improved pasture management” – Prof Jacqui Matthews.
Following reports that equine tapeworm drugs may be losing efficacy, Austin Davis Biologics (ABD) has reissued its guidance on the use of EQuiSal salvia testing for informing tapeworm control.
A recently published study from the Department of Veterinary Science at the University of Kentucky found evidence of treatment failure of praziquantel and pyrantel, the only two drugs licensed in the UK for tapeworm control in horses.
Responding to this development, ABD is emphasising that owners should not repeatedly test and treat for tapeworm without evaluating management, as this could lead to resistance.
Professor Jacqui Matthews, director of veterinary science at ADB, said: “In horses that report with a borderline or moderate/high saliva score, their management should be evaluated to determine what improvements could be made to help prevent tapeworm reinfection from the pasture.
“As part of this evaluation, a follow up test can be performed three months after treatment to provide information on whether or not reinfection is occurring.”
In cases when horses test positive in the follow up test, Prof Matthews said: “Improvements in pasture management should be undertaken, and/or a tapeworm treatment considered where appropriate, to prevent further grazing contamination with tapeworm eggs.
“All co-grazing horses should be tested at the same time in case they act as a continued source of tapeworm eggs. The best approach to prevent wormer resistance is to evaluate and implement improved pasture management to move to a situation where recurring reinfection is considerably reduced.”
ABD suggests that when saliva scores stay high despite taking the suggested measures, anthelmintic resistance should be considered a possibility. In such cases, the company recommends that owners seek advice from their veterinary surgeon.
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Companies marketing medicines for small pets exempt from authorisation must submit their annual return to the Veterinary Medicines Directorate (VMD) by 30 November 2026.
