Worms growing increasingly resistant to parasiticides - Elders Rural Services

Worms growing increasingly resistant to parasiticides

Studies show infected cattle under perform by 7.4 per cent (pc) in average daily weight gain1 and can have 5.4 pc lower feed intake1.

Dr Matthew Petersen, Livestock Operations Manager at Zoetis recommends that producers consider six questions before selecting a cattle drench:

  • Is the drench being used for weaners and young, growing cattle?
  • Are you buying cattle in or bringing cattle back from agistment blocks?
  • Are cattle being inducted into a backgrounding or feedlot facility?
  • Have you been disappointed by previous results from drenching?
  • Have you had parasite resistance diagnosed on your farm?
  • Do you also need to control ticks and/or lice?

He added that if you answered ‘yes’ to any of these questions, then you should consider using a dual active drench to ensure a high efficacy worm kill and to either prevent parasite resistance developing on your farm or break existing resistance profiles.

The benefits of Dectomax V

Dectomax V has just been released to the market. It’s Australia’s first injectable dual active drench.

Dectomax V is ideal for all weaners and young, growing cattle which are most economically impacted by worms. Given its very high treatment efficacy, Dectomax V is ideal as a quarantine/induction drench to prevent resistance worms entering a farm with brought in stock. It can also be used in replacement breeding stock, such as replacement heifers and where necessary can be used in adult cattle. It’s an ideal product for use on entry to backgrounding and at induction prior to feedlot entry to ensure resistant worms don’t hinder weight gain.

Dectomax V is an evolution from Dectomax which has been trusted and used across Australia for over 20 years.

Dectomax V combines the trusted performance of doramectin, from Dectomax, with the added strength of levamisole. Dectomax V is the first injectable ML/Levamisole combination product registered in Australia and provides a dual active killing power with unsurpassed efficacy against key parasites, including those often resistant to other single active drenches.2-15

Dectomax V was also compared to leading drenches in Australia.  The results were outstanding, with an overall mean efficacy of 99.8 pc across 13 studies.16 Notably, two leading single active ML drenches used for comparison, both showed results less than 95 pc, indicating a growing level of resistance to this drench class.

Providing high efficacy, this broad spectrum parasiticide with new dual active technology is designed to kill the most damaging parasites, including resistant worms. Easy injectable administration results in highly reliable dosing. In addition to treating gastrointestinal worms, it also controls cattle tick and sucking lice.

Dectomax V product claims*

  • For the treatment and control of adult and L4 larval (immature) stages of gastrointestinal worms, including both macrocyclic lactone and levamisole resistant strains
  • For the treatment and control of Cattle tick – prevents the development of viable ticks for 30 days after treatment
  • For the treatment and control of Sucking lice – 56 days
  • Safe for use in calves from three months of age and at all stages of pregnancy
  • Meat withholding period and export slaughter interval: 35 days

Article written by Zoetis for Seasons magazine


1. Stromberg, B. E., et al. (2012). “Cooperia punctata: effect on cattle productivity?” Vet Parasitol 183 (3-4): 284-291.
2.Zoetis Inc. DECTOMAX V Australian Product Information. 2021.
3-15: Zoetis Studies: A3580, A3595, A3596, A3798, A3881, A3809, A3858, A3861, A3862, A3863, A3864, A3860, A3859. Data on file.
16. Overall mean efficacy (GM) of 99.8% across thirteen field studies. Zoetis data on file.
*Refer to product label for registered label claims.

Dectomax V is available from your local Elders branch.

Order Now