Worming and pasture management

Worming and Pasture Management

Worming and Pasture Management

Why do we need to worm?

Worms in excessive numbers cause many gastrointestinal problems in horses, ponies and donkeys. A combination of pasture management, worm egg counts (WECs) and targeted worming will ensure that these worm burdens are kept to a healthy level and minimise the risk of disease

When to worm?

It is important that you discuss each premises and horse needs with your veterinary surgeon, so advice can be tailored to individual circumstances.

On premises where there is little movement of animals and pasture management is good, then WECs and targeted worming are recommended. This ensures those animals with a higher burden are treated, whilst those with low counts are not wormed unnecessarily. Note that a once yearly treatment for red worm larvae and tapeworm is still essential.

Not only are WECs a more cost effective means of ensuring the health of your horses, but they reduce the chance of parasites developing drug resistance. This would result in wormers being partially effective or completely ineffective – a very concerning situation that is already developing (much like antibiotic resistance).

Pregnant and lactating mares and foals may only be treated with certain wormers. Discuss this with your veterinary surgeon and always follow manufacturer’s recommendations

Worms can cause

  • colic – medical and surgical
  • weight loss and severe diarrhoea
  • impactions (blockages)
  • poor growth of youngsters
  • blockages in intestinal blood vessels
  • hair loss/itching around the tail head

Key points

  • Discuss a tailored worm control program with your veterinary surgeon
  • Ensure annual treatment for red worm larvae and tapeworm
  • Perform WECs counts every 3-4 months
  • Maintain your paddocks well by dropping collection at least twice weekly

Make a plan

Any new horse/s on the premises should be wormed with a product that kills red worm larvae, tapeworm and roundworm. The animal should then be isolated for 2-3 days prior to turn out on grazing, to allow time for all the worms and larvae to be killed.

Ensure every horse is dosed correctly according to their weight. Weigh tapes are available, or your veterinary clinic may have scales for a more accurate measurement. If you are in doubt ask you veterinary surgeon to advise you on your horse’s weight. Keep a record of which wormer was given to every horse and when it was administered, along with any WEC results.

Talk to your veterinary surgeon about a plan for your premises. Ideally, review the system yearly, particularly if there are any major changes in yard management.

Adult tape worm on a rectal glove

Pasture management

  • Pasture dropping collection should be carried out at least twice weekly
  • Harrowing of manure does not kill eggs as the temperatures in the UK are not reliably high enough
  • Even manure that has been composted cannot safely be spread onto pastures, as only the very centre of the heap will have got hot enough to kill the worm eggs

Types of wormers

(Check product packaging for more information).

Fenbendazole: Will treat encysted small red worm larvae if used for 5 consecutive days, but some resistance reported. Will also treat large and small redworm and large round worm

Pyrantel: Can be used from 4 weeks old. Double dose will treat tapeworm. Also treats adult redworm and large roundworm

Ivermectin: Treats most stages of redworm and roundworm

Moxidectin: Treats encysted red worm larvae and roundworm. Not for use in foals <4months

Praziquantel: Treats tapeworm only