Choose drenches that you know will work for you
Zolvix® (monepantel) is a broad-spectrum drench, from a completely novel drench class, that is >99.9% effective against the most common, damaging and economically important worm species on Australian farms1. There is no resistance to Zolvix2, so you can be entirely confident in choosing, using and incorporating Zolvix in your drench rotation. You know that it will work for you even if you do not know the resistance status of other drench classes on your farm — or if resistance to other actives on your farm is already severe.
But what else should you use in rotation with Zolvix? You don’t want to use drenches that don’t work – and ultimately that is what resistance means. Industry advisors therefore recommend carrying out a drench resistance test – a worm egg count reduction test (WECRT) – on your own property every 2-3 years to make sure you know what drenches will work for you. This helps make sure that the right drenches can be used at the right time to minimise the costly impact of worms and to help optimise production.
For the first time in nearly 20 years, a national survey of drench resistance has been conducted, using the data from those farmers and advisors who do carry out regular testing. Just published in the Australian Veterinary Journal in December 2014, this survey indicates how serious and widespread drench resistance has become3.
Table 1: National summary of percentage of WECRTs with <95% WECR in sheep.
*Any worm = One or more of the following: Brown stomach worm, Black scour worm or Barber’s pole worm.
BZ=Benzimidazole; LEV=Levamisole; NAP=Naphthalophos; IVM=Ivermectin; ABA=Abamectin; MOX=Moxidectin; MPL=Monepantel
Table 1 shows that 96% of properties had resistance to the white (BZ) and clear (LEV) drench groups. On only 4% of survey properties would BZ or LEV be effective drenches against all of the major worm species. 30% of survey properties even had resistance to LEV in Barber’s Pole worm, generally assumed by many farmers to be an effective drench against this life-threatening worm.
The prevalence of resistance to the MLs was also dramatic. Moxidectin resistance was evident on 54% of survey properties – despite being the most potent of the MLs on the market for sheep! 77% of survey properties had resistance to abamectin, with resistance particularly common in brown stomach worm and Barber’s Pole worm.
Combination treatments have been widely advocated to slow the development of drench resistance and have remained useful on some properties through additive efficacy. However, combinations that rely on the older single-actives with widespread resistance (such as abamectin) won’t necessarily be fully effective if they rely on other actives that may not be fully effective either. 28% of survey properties had resistance to the abamectin-based triples, as shown – and 81% of properties had resistance to the traditional BZ/LEV combination.
The abamectin-derquantel combination was not available for testing at the time the study was conducted, but derquantel is known to be a mid-spectrum active with variable efficacy(≤95%) against Brown stomach worm and Barber’s Pole worm (L4 stage)4 – so the efficacy of abamectin is crucial if this combination is to be considered.
Fortunately, Zolvix is known to be effective even against resistant worms – including those resistant to 3 or even 4 other drench groups5. As it is likely that we will need to continue to rely on the older drench classes for some time to come, it is therefore critically important to incorporate Zolvix into your drench rotation now. This will help protect the older actives, slow the development of resistance6 and help ensure you have useful drench options available in the years ahead.
- Kills >99.9% of Barber’s pole, Brown stomach and Black scour worms. Hosking BC et al. A pooled analysis of the efficacy of monepantel, an amino-acetonitrile derivative against gastrointestinal nematodes of sheep. Parasitol Res 106, 529-532, 2010.
- Zero resistance – No monepantel resistant nematode populations exist in sheep in the field.
- Playford MC et al. Prevalence and severity of anthelmintic resistance in ovine gastrointestinal nematodes in Australia (2009-2012). Aust Vet J 92, 464-471, 2014.
- Little, PR et al. Efficacy of a combined oral formulation of derquantel+abamectin against the adult and larval stages of nematodes in sheep, including anthelmintic-resistant strains. Vet Para 181, 180-193, 2011.
- Baker, KE et al. Efficacy of monepantel and anthelmintic combinations against multiple-resistant Haemonchus contortus in sheep, including characterisation of the nematode isolate. Vet Para 186 (3-4), 513-517, 2012.
- Dobson, RJ et al. Minimising the development of anthelmintic resistance, and optimising the use of the novel anthelmintic monepantel, for the sustainable control of nematode parasites in Australian sheep grazing systems. Aust Vet J 89, 160-166, 2011.
ZOLVIX® contains 25 g/L monepantel, a member of the Amino-Acetonitrile Derivatives (AADs) class of anthelmintics.
For full product details contact NOVARTIS CUSTOMER ADVISORY LINE on 1800 633 768 TOLL FREE between 8.30am and 5.30pm E.S.T. Monday to Friday Novartis Animal Health Australasia Pty Limited, ACN 076 745 198, 54 Waterloo Road, North Ryde NSW 2113. ZOLVIX® is a registered trademark of Novartis AG, Basel, Switzerland