Worms have been part of a horse’s life for thousands of years. In the wild they’re less of a problem because horses can keep moving to fresh pasture, but domesticated horses can’t do that so we need to be aware of the worms out there to keep our horses healthy.
Here are 5 of the most common worms
1. Redworm
These come in a couple of different types. Large redworm, small redworm and encysted small redworm. Small redworm are the most common and reproduce quickly. Large redworm has been reduced massively over the last 40 years, but can cause problems in their migratory stage. Both large and small redworms can be detected using egg counts.
The encysted small redworm is a particular stage in the lifecycle of the small redworm. As larvae they borrow into the gut wall and can remain dormant in there for months or years. They can’t be detected by a regular faecal egg count, but they can be picked up by a blood test. If your horse has had a very high egg count in the past, it’s worth talking to your vet about this as an additional check.
2. Tapeworm
These are the ones that everyone has heard of because they can affect humans too. They live in the intestine and latch onto the gut wall, living off the food that horse’s eat. Tapeworm can be tested for using an easy saliva test, this will tell you if your horse needs to be treated.
3. Pinworm
These worms are on the rise in horses and can be tricky to treat. They live near the end of the digestive tract and some of the signs that they’re affecting your horse include excessive scratching of their hindquarters or tail. Pinworm are unlikely to show up in an egg count because the eggs tend to be laid around the anus, but you can use some sticky tape to collect any eggs under the tail then send the tape off for testing to find out the worm burden for your horse.
4. Roundworm
These are large white worms which can grow up to 40cm long! They’re more likely to affect younger horses, but you should be aware of them no matter the age of your horse. They can be tested for using worm egg counts in the same way as redworms.
5. Bots
These technically aren’t worms, they’re fly larvae, but they can still cause a problem for your horse. The Bot fly lays their eggs on the horse’s coat, when the horse itches themselves, they eat some of the eggs. These eggs hatch in the horse’s mouth and make their way into the digestive system. These can’t be tested for because they don’t lay eggs in the intestine, but if you see eggs on any of the horses in the field there’s a high chance that they’ll be on all the horses.
The biggest threat facing horse owners at the moment is an increase in worm resistance to the drugs in horse wormers. If this isn’t tackled, it’s likely that in the near future we won’t have anything we can use to help our horses. There are currently only 5 drugs which are effective in treating worms in horses.
Luckily there is a lot you can do as a horse owner to help reduce the spread of wormer resistance and you can find out more in this month’s webinar HERE