[Resistance of small strongyles in an equine stud in South Africa to the benzimidazole anthelmintics].

The research article documents the first reported case of resistance to deworming drugs in worms found in horses in South Africa. Despite the previously observed effectiveness of benzimidazoles, one particular breed of worm in an Arabian horse showed a reduced response to this treatment, though it was still responsive to ivermectin. The researchers suggest alternative methods of control, including rotating grazing animals and physically removing faecal matter.

Objective and Methodology

• The study aimed to investigate the growing issue of resistance among horse parasites in South Africa to commonly used anthelmintic drugs, specifically benzimidazoles.
• The research focused on a strain of Cyathostominae (small strongyles or horse roundworms) found in an Arab stud farm near Pretoria. As an investigative tool, faecal egg reduction tests were conducted to gauge the susceptibility of these parasites to the anthelmintics.

Findings

• The findings demonstrated that the studied strain of Cyathostominae showed a significantly reduced susceptibility to benzimidazoles. This is the first time such resistance has been reported within South Africa, furthering the global concern over anthelmintic resistance in equestrian helminths (parasitic worms).
• Interestingly, the worms remained responsive to another class of anthelmintic drugs known as ivermectin, indicating potential alternative treatment pathways.

Recommendations

• Given the evidence of drug resistance, the researchers suggest that further reliance on anthelmintics alone is insufficient for sustainable worm control in horses.
• They propose integrated methods of control such as rotating pasture-grazing between different species (horses and ruminants) to disrupt the worm lifecycle, and mechanically removing horse faeces to limit worm reproductive capacity.
• The recommendation to explore alternative treatment strategies, such as using different classes of anthelmintic drugs like ivermectin, aligns with global efforts to manage growing anthelmintic resistance.