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Rotational worming is not just swapping brands.

Rotational worming is not just swapping brands.

Article by Dr. Tanya Leslie, BSc BVSc Product Manager – Ceva Animal Health & Dr. Finola McConaghy, BVSc, DipVetClinStud, PHD Technical Manager – Ceva Animal Health.

Historically it has been recommended to deworm adult horse approximately every 6 – 8 weeks with a broad spectrum wormer. It is now recommended to worm based on faecal egg counts(FEC) to hel reduce resistance development. Using the same product repeated encourages resistance to develop. Rotating between different classes of wormers will reduce reisstance. There are 3 main classes available for use in horses.

  • Macrocyclic Lactones (ML) – ivermectin, abamectin and moxidectin
  • Benzimidazoles (BZ) – oxfendazole and fenbendazole
  • Pyrimidines – pyrantel and morantel

What’s the difference between drugs in the same class?

When planning your rotational program, it is important to choose products from a different class. For example, if you are currently using moxidectin and praziquantel, you should consider using something like exfendazole.

Do long-acting wormers really last a long as they claim?

When ivermectin products were first launched, the egg reappearance period (ERP) after deworming horses was eight weeks and for moxidectin-based products it was claimed to be around 14 weeks.
During a recent Australian study, horse owners submitted follow-up faecal samples in weeks after the initial faecal egg count reduction test (FERCT) which suggested that cyathostome egg shedding is starting faster than expected after worming with moxidectin and was below 12 weeks in some areas(4).

Horse owners in the USA have also recently reported shortening ERP times following both ivermectin and moxidectin treatments (just 4 weeks in some cases)(5).


  1. AMMO® ALLWORMER is a combination product consisting of the newer, safer molecule marantel(3) and abamectin. The combination of  abamectin and marantel with similar efficacy will help reduce resistance development.
  2. AMMO® ALLWORMER comes in a new peppermint flavour, one of the top flavours chosen by horses(6).
  3. Recent studies conducted on properties in the Hunter Valley, Riverina and Sydney demonstrate that AMMO® ALLWORMER had greater efficacy against resistant ascarids than Equimax(1,2) and maintained a consistent ERP of 8 weeks under Australian field conditions.
  4. AMMO® ROTATIONAL contains oxfendazole, an easy-to-use rotation partner.

For more information – visit www.ceva.com.au 

To purchase AMMO® ALLWORMER and AMMO® ROTATIONAL, head over to your local Tuckers Store member or shop online here.


  1. Wilkes EJA, et. al. Aust Vet (2017) J 95(3): 85-88
  2. McConaghy FF, et. al. Aust Eq Vet (2015) 34:39
  3. Veterinary Pharmacology and Therapeutics, 7th Edit. (1995) 908
  4. Beasley AM, et al. Veter Parasitol (2017) 8:127 – 132
  5. Lyons ET, et al. Parasitol Res (2011) 108:355-360
  6. Goodwin D, et al. App Animal Behav Sci (2005) 95: 223-232

CEVA Animal Health Pty Ltd. PO Box 147, Glenorie NSW Australia 2157.