How to worm your horse effectively

Worming our animals is an essential part of keeping them healthy. While giving regular treatment to our small furry friends, like cats and dogs is relatively straightforward, it might seem more difficult to worm your horse. 

It’s likely that your horse is much bigger and more reluctant than your average household companion! Not only that, but worms can be found in a lot of places – from grazing pastures to horse feed – and can easily make their way into your horse’s stomach. 

There is also a wide range of worms that can be found in horses. These include:

• Tapeworms
• Roundworms
• Pinworm
• Large and small strongyles, also known as small and large redworms

Unfortunately, parasites are becoming increasingly resistant to worming products so you should only worm your horse when it is necessary. 

To ensure that you’re making the most of worming your horse, you should test for the presence of worms using a faecal egg count (FEC). If there is a presence of worms, you know that you can then go on to administer the worming treatment to rid your horse of the parasites.

Look to the year ahead

It’s important to know what kinds of worms and parasites to look out for and during which season, as how and when they are treated can impact the parasite’s development and potential to impact your horse throughout the year. 

Here’s a simple outline, and your vet can help you with a tailored plan according to your horse and their environment.

Spring: Getting on top of worming during Spring will get you on track for the year ahead. Small redworm, a type of roundworm, is prominent during this time and it’s also worth testing for tapeworms between March and April. Only treat a horse that gives positive results to reduce the chance of resistance. 

Summer: Carry out regular faecal egg count tests to establish whether your horse has worms, and treat your horse if needed. This will help you keep track of your horse’s worm burden throughout the season. 

Autumn: Conduct a suitable test (e.g. a saliva test) for tapeworms between September and October, and focus on managing small redworm and bots late into the autumn months. It’s key to worm for encysted small redworm around this time, or in early winter as they usually emerge between late winter and spring. This ensures that the adult flies are killed by frost and can’t lay eggs. 

Winter: Assess the risk from pasturing before determining whether it’s necessary to worm your horse around this time. It’s likely that a horse that has been treated in late autumn won’t need to be treated again, but be vigilant for tapeworm and pinworm during winter.

Factors to consider

As with smaller animals, there are factors that you should consider when it comes to worming your horse. Arguably, the most important factor is their weight. 

The weight of your horse impacts how big or small of a worming dose they need, so they should be weighed every time they’re wormed. The bigger your horse, the more they will need. Please don’t guess, but instead work out their weight so you can give the correct dosage. 

Under dosing means the treatment won’t be effective, in a similar way to a person only taking some antibiotics rather than the full, prescribed course. The worms will become resistant even faster than they are already, so if you do need to worm your horse it’s essential that you’re not underdosing them and encouraging resistance. 

If you’re not sure how to weigh your horse, use this simple calculation.

Using inches, measures heartgirth x heartgirth x body length divided by 330 to calculate the weight of your horse in pounds.  

Minimising the risk

Just as we choose to be vigilant for fleas in our homes, every horse owner should be mindful of the things they can do to reduce the number of worm eggs in a horses’ environment. Although it isn’t a guarantee that your horse won’t get worms, it’s one of the most effective ways to minimise the risk!

This includes avoiding over stocking pastures, keeping in mind that one and a half acres per horse is the recommended advice. Rotate pastures where possible, leaving them to rest for several months to allow strong sunlight and frost to work their magic and reduce the chance of eggs and larvae surviving.

Removing faeces from your horse’s grazing pasture is key too. Doing this regularly will reduce the risk of your horse ingesting worms. 

Signs your horse has worms

Horses display a number of symptoms if they have worms. These include:

• Weight loss
• Poor appetite
• Colic
• Lack of energy
• Diarrhoea or constipation
• Respiratory problems
• Rough coat

It’s important to spot the signs early so you can effectively treat your four legged friend. By following a seasonal regime and treating your horse accordingly throughout the year, your horse should manage to avoid serious side effects thanks to vigilance and quick action. 

It can be dangerous to ignore these signs, so once you’ve established that your horse has worms, it’s important to treat them. 

Browse our range of horse worming treatments here.

Neil’s top tips:

• Horses can be reluctant and difficult to worm, so find a treatment that is not only suitable to treat the problem, but is also simple to administer.
• Keep your horse’s pasture and stable as clean as possible to help reduce the worm burden and protect them from parasites year round.
• There are a number of different tests that serve different purposes, so be sure to learn as much as possible about how these work and how they should be used – your vet can help with this.
• Targeting the right parasites during the right season is key to effective treatment of your horse. 
• Remember, getting the dosage right is crucial! The more resistant parasites become to wormers, the more difficult it will be to control them and keep your horse free of infestation.