We all have a responsibility to use equine worming products appropriately. Many equine worm species are developing resistance to wormers due to frequent, untargeted use of these products and there are currently no new active ingredients coming to market. Ensuring wormers remain effective, by only using them when needed, is vital for the future health and wellbeing of our horses, ponies, and donkeys.

Your veterinary surgeon is the best person to understand your horses individual worming needs. They can create a targeted testing and, if applicable, treatment program specific to your animal(s) and their environment. Screening before dosing is straightforward (using manure, saliva or in some cases, blood samples) and by only treating animals showing a worm burden it helps ensure you can worm your animal(s) effectively while also reducing the likelihood of resistant worms developing

You can learn more about the current issues with resistance and the strategies being put in place to try and protect the effectiveness of horse wormers by visiting the CANTER website 

When testing has shown it is appropriate to worm your horse, horse wormers should be used in a responsible way, at the correct dose rate and during the correct season.

To dose your horse correctly you will need to either weigh your horse or know its weight as accurately as possible. Underdosing can contribute to the worm resistance that is already being seen, whilst overdosing can also be potentially dangerous for your horse.

You can use a weigh tape or a calculation to estimate your horse's weight, although the latter is considered slightly more accurate:

Heart Girth² (inches) x Body Length (inches) ÷ 300 = weight (lbs)

Testing to determine your horse's worm burden is vital as some horse worms can have a huge impact on your horse's health. Encysted small redworm larvae and tapeworms are two parasite infestations which can require veterinary intervention and treatment: treatment which can run into thousands of pounds. Small redworm are the most common and harmful parasite to affect your horse today, over 90% of which can be encysted in your horse's gut wall. Killing these encysted larvae in the late autumn and early spring, before they emerge and cause potentially fatal intestinal damage, is an important part of any worm control programme.

Tapeworms are responsible for a number of health-related problems in horses, ranging from loss of performance and hair loss to diarrhoea, colic, and painful, potentially fatal perforation of the intestine.