Hello spring! This is a beautiful season where the sun comes out and pastures start to flourish. It is also an important time to start thinking about parasite control for horses to help to prevent worm related illnesses. This article aims to explain why we worm horses in spring and management strategies to ensure optimum equine health.
Why do we worm horses?
One of the most common questions people ask is, ‘why does my horse need worming?’ If your horse has a major worm burden, their guts can become damaged and they can become extremely poorly. It can lead to your horse displaying colic symptoms, diarrhoea and it can sometimes be life threatening. Prevention is always better than cure, so having a structured worming plan in place is key to successful equine management.
What risks are present in spring?
Most parasite life cycles that can affect horses are seasonal, meaning that depending on the time of the year they can pose higher or lower risks. The following points discuss the parasitic problems horses may encounter during springtime:
- Encysted small red worm – encysted small red worm (cyathostomins) have the potential to emerge en mass during the spring from the large intestine, damaging the gut and leading to impaction colics, weight loss and sometimes death. To prevent this and to reduce this risk, horses should be tested for and treated for red worm during the winter period. Treatment should only be administered if your horse’s faecal egg count is above 200 eggs per gram during the worm season.
- Tapeworm – spring is an important time to consider tapeworm (Anoplocephala perfoliata) cover for your horse. Horses only require tapeworm cover twice yearly, in spring and autumn, and therefore if your horse receives treatment every 6 months, this parasite should be kept under control. Testing for tapeworm prior to treating is advised to ensure responsible use of horse wormers. This can be conducted via a tapeworm saliva testing kit or a blood test.
- Bots – bot flies are unique parasites! The flies lay their eggs in late autumn and bot larvae develop in the stomach over winter, treatment in spring is recommended if you’ve seen bot fly eggs on your horses the previous autumn.
What wormers are available?
There are many brands of horse wormer currently available. Wormers may also contain different drugs and it important to consider this before giving your
horse a wormer. Depending on the season and parasitic risk, different worming drugs will be recommended. There are 4 different classes of anthelmintics:
1. Benzimidazoles e.g. fenbendazole – a 5 day course of fenbendazole will treat red worm, although resistance is quite common.
2. Tetrahydropyrimidines e.g. pyrantel
3. Macrocyclic lactones e.g. ivermectins/avermectins/moxidectin – a single dose of moxidectin will treat red worm. Ivermectins or moxidectin will also treat bots.
4. Praziquantel based wormers – a single tapeworm treatment only.
Anthelmintic resistance is sparking more interest than ever before, and we need to remain responsible with our worming product use. Similarly to the hugely topical world of antibiotic resistance, anthelmintic resistance is a concerning and emerging issue. As horse owners, we remain responsible for minimising drug resistance, and we want the product to be as effective as possible. Ways in which we can remain responsible is by ensuring the wormer is administered at the correct dose for that horse’s weight. Under-worming can be an issue, as can over-worming! Also, using the correct type of wormer is essential, if the same drug is repeatedly given, resistance may be more likely to develop.
What are faecal egg counts?
Faecal egg counts (FEC) have been developed over the years to try to combat the degree of anthelmintic resistance. This test is carried out multiple times a year and will determine whether your horse and the herd requires a wormer, leading to a more targeted worming approach. For example, if your horses FEC results are below 200 eggs per gram, your horse almost certainly does not require a wormer. Additionally, it is important to understand that FEC’s do not detect encysted red worms or tapeworm, therefore alternative testing and treatment at the specific time of the year is highly recommended.
To conclude, to worm horses correctly and strategically, it requires some thought into the parasitic risk during specific seasons. Please speak to your local equine Vet or one of our SQPs for advice on what wormer to use and when! They will guide you on the products available. Worm egg count kits are available on our website here, Tapeworm test kits here, and we stock a wide range of horse worming treatments.