Tackling Resistant Worms in Horses
Resistance worms are now becoming a ubiquitous and serious issue among horses. Although owners are seeing the benefits of faecal worm egg counts, (as they prevent unnecessary overdosing which aids the development of resistant worms) this does not help when deciding what treatment is best for their horse. As supported by Ben Gaskell in this months Veterinary Practice, who states that:"It's important to recognise that Faecal Worm Egg Counts (FWECs) have limitations and must not be regarded as a complete solution for worm control."
Gaskell explains there a various treatments and some can be categorised under two labels; Macrocylic Lactones and Moxidectin. These indicate which chemicals are present in the treatment, as well as the way they are released in the horse's body. For example, the group of Macrocrylic Lactones (ML) are aimed to treat roundworm, encysted small red-worm and bots. The different treatments available within this group however, vary and are aimed to suit to different horses and their needs. Gaskell's alternative chemical group of Moxidectin, mainly works by being released from the horses body fat. Naturally, this would suit some horses more than others, depending on their breed and breeding purpose.
Ultimately, Gaskell makes these distinction, in order to emphasize that when treating horses for worms, vets must consider such variations in treatment, whilst at the same time, keeping in mind each horse (and horse owner's) preferences and circumstances.
Companies marketing medicines for small pets exempt from authorisation must submit their annual return to the Veterinary Medicines Directorate (VMD) by 30 November 2026.
