It is important to keep horses free from illness, and as a horse owner you need a plan of action for controlling worms. The parasite life cycles that can affect your horse are linked to the seasons. So your worming schedule should take into account the time of year.

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Why do I need a seasonal worming schedule for horses? 

As a responsible horse owner, it is important to consider the problem of resistance. There is an increasing threat of worms becoming resistant to the chemical ingredients which are in the wormers. 

It is no longer acceptable to dose all horses routinely throughout the year.

It is more and more acceptable to dose correctly, as little as possible but as much as necessary. This can be achievable by assessing every horse individually, always practising good pasture management and using faecal worm egg counts (FWECs) appropriately.

What do I need to worry about in Spring?

This is when encysted small red worms mature and emerge from the large intestine, damaging the gut wall. This can cause  health problems for your horse, including weight loss, diarrhoea colic and sometimes death.

Ideally if you have tested or treated effectively over the winter months, you shouldn’t have a problem. But it is important to remember that if your horse is experiencing unexplained health conditions, it is vital to contact your vet immediately.

Spring is the perfect time to start faecal worm egg counts (FWECs) to identify horses needing treatment. It is important to remember that FWECs are never 100% accurate. The reason for this is because not all parasite’s eggs are easily detectable and some parasite stages don’t lay eggs.

The number of eggs produced by parasites will vary from horse to horse even if they have the same level of worm burden. But FWECs can show if the horse has a high burden and can also show the horses passing (shedding) the most eggs and contaminating the pasture – which is very important to know.

What worms do I treat for in the spring?

Treat your horse in spring for:

Tapeworms 

Treating at the beginning and end of your grazing season at roughly six months apart is usually needed to keep this parasite under control. You can also test for antibodies to tapeworm in your horse’s blood or (better) saliva but expert advice is needed to correctly interpret the result.

Encysted small red worm

Treating a horse that has not previously been given a wormer effective against the encysted small red worm in the previous autumn/winter period is advised. 

Red worms 

Treatment is usually recommended if FWECs are greater than 200epg (eggs per gram).

Bots 

The bot fly lays its eggs in late autumn and bot larvae develop in the horse’s stomach so they should be treated in the spring.

How to perform FWEC

A vet and some qualified SQPs can perform FWEC for you. Or you can send a sample off to specialist laboratories who send you a kit. Just ask your vet or SQP for details on the amount of faeces needed.Worm egg counts only show up small roundworm eggs and are done through the spring and summer months because in the winter months, small roundworms go into a dormant state so won’t be producing eggs.Tapeworms only produce eggs at certain times, and shed them in segments rather than singly, so won’t usually show up in FWEC. They can be detected by a blood test or saliva test.

It is recommended that horse owners perform FWEC every eight weeks from spring through to autumn, but it does depend on individual circumstances.Young horses or older horses with lowered immune systems may be required to be worm egg counted and wormed more often.An example is  young foals, they have no immunity to threadworms which can be passed from the mare. Infection can then leave them weak and susceptible to diarrhoea and anaemia.

What should I do before giving the wormer?

Before giving the horse a wormer, it’s important that you have an accurate weight measurement so you know how much to give the horse. Unfortunately under dosing can add to the  resistance issue, so it’s important you get the dosage right.  

How do I give a wormer? 

Wormers for a horse come as a paste in a syringe that you can syringe straight into the horse’s mouth. Most horses will accept the wormer. If the horse is difficult, you could practise giving the horse a syringe of something nice such as apple or molasses. This will help the horse to associate the syringe with something tasty.

If you need advice on worming or worm egg counts, please speak to your veterinary surgeon or SQP.

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