Resistance to antiparasitics such as dewormers and tick treatments is a growing problem in livestock farming. Veterinarians warn that the incorrect use of products and poor management practices are making the situation worse.
By Jasper Raats, senior journalist at African Farming and Landbouweekblad
During a panel discussion on animal health at the recent AgriHX Expo in Polokwane, Limpopo, veterinarians said that resistance against antiparasitics was already widespread and that farmers urgently needed to adopt more structured herd health programmes.
Dr Duncan Green of Green Partnership said resistance was often first noticed when a product no longer delivered the expected results.
With ticks, this is relatively easy to detect: If a dip or pour-on treatment is applied and only some of the ticks die, it indicates resistance in the tick population. In such cases, producers should collect samples of engorged ticks and have them tested by a veterinarian or laboratory to determine which active ingredients resistance has developed against.
With internal parasites such as worms, the problem is more difficult to identify because it is not visible to the naked eye. Green suggested a faecal egg count reduction test, in which dung samples are collected before and after treatment and compared. If a significant number of worm eggs remain after treatment, this indicates that the remedy is no longer effective.
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Dr Nico du Preez of Kyron Agri emphasised that resistance was not always the fault of the product itself. Incorrect dosing, faulty administration and other factors can affect a remedy’s effectiveness. Farmers should therefore first consult a veterinarian or the medicine manufacturer’s representative before assuming resistance has developed.
Dr Dario Cremona of the Pietersburg Veterinary Clinic said prevention remained key. Farmers should follow a structured herd health programme from the outset, including vaccination, deworming and dipping at set intervals.
Green emphasised that animal health mistakes could not simply be “fixed later”, and that consistent programme implementation was essential.
Dr Roelf van Rooyen, a veterinarian from Polokwane, recommended that farmers work closely with veterinarians and other experts to develop farm-specific strategies. This includes rotating remedies, avoiding unnecessary treatments and carefully monitoring animals.
Failure to address resistance in time can have serious economic consequences. Lower production, higher input costs and increased mortalities can place significant pressure on profitability. By recognising early warning signs and following expert advice, farmers can reduce these risks.
