WEB Vetnews May 2015

Regulars I Zoetis pages

Production Animal Column

FOR ANIMALS. FOR HEALTH. FOR YOU.

Worm Resistance: A threat to industry Dr BB van Houten, Zoetis™ Resistance to anthelmintics is becoming a big problem for sheep farmers around the world and should be addressed very quickly to help prevent its further development. In South Africa, 96% of farm samples tested showed resistance to at least one anthelmintic product, while barbers pole worm ( Haemonchus contortus ) resistance is now common in many countries.

T his is according to Dr David Bartram, Director, Marketing & Integrated Solutions - Ruminants, Zoetis, recipient of the British Veterinary Association’s Chiron Award 2013 for outstanding contributions to the veterinary

is present. Resistant worms do not cause more serious disease than susceptible worms.” In order to use anthelmintics sustainably the following guidelines are important: Dosing strategy • Plan a dosing strategy • Don’t use blueprints or a set recipe. Tailor the planning for the individual farm. • Use an effective, multiple active wormer, such as Startect (Derquantel and Abermectin). Quarantine It is important to quarantine and treat all introduced sheep on arrival. Hold these sheep off new pastures for at least 24 to 48 hours before turning them out into contaminated pastures. No matter how expensive the animal... it could still carry resistant worms.

ability on to its offspring. Managing resistance is important since production losses can occur even when the parasitism caused by anthelmintic resistance is subclinical. By using an

affective anthelmintic growth performance is increased and the benefits can greatly exceed the costs of the anthelmintic.

profession, and a veterinary scientist and author. Resistance is the heritable (and therefore genetic) ability of the worm to survive a

Dr Bartram cautions that resistance is inevitably a consequence of good worm control and could emerge within two to four years with some products. “Once resistance has emerged in a flock, the worms can no longer be controlled effectively using a particular anthelmintic class. However, in most flocks or herds, worms can still be adequately controlled when resistance

dose of anthelmintic which would normally be effective. It could also be described as ‘drug tolerance’ in worms. A worm is said to be resistant if it survives exposure to the standard recommended dose of the anthelmintic and can then pass this

vet nuus • news

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Mei/May 2015