Worming Diary

Horses should be wormed every 6 to 12 weeks. A wormer has yet to be invented which treats all parasites, so it is very important to work out an annual routine incorporating different wormers with your Veterinary Surgeon.

The following is an example worming chart based on horses in the UK.

Before worming your horse it is advisable to consult your veterinary surgeon about suitable doses, which are dependent on the weight of the animal and the type of wormer (anthelmintic). Knowing your horse's weight is vital when worming. Manufacturers advise horse owners to check the weight of their horse, either by using a weighbridge or, by using a girth measuring tape, before deciding on a suitable dose.

Do not simply go on height and build; a 16hh Thoroughbred will be a different weight to a 16hh Irish Draught.

Powder Or Paste

Anyone who has ever attempted to worm a horse knows how difficult it can be despite manufacturers devising numerous ways to make the medicine palatable.

Granules, powders or pellets can be mixed with a horse's feed but you need to keep a close eye to ensure the entire dosage is eaten. Many horses will careful separate their feed from the wormer, leaving the drug in the bottom of his bowl.

Alternatively the wormer can be given in the form of paste by oral syringe. Worming in this way is an art if you are not going to end up wearing most of the paste.

Chemical Groups - Commercial Wormers

Every wormer contains one of five ingredients, namely Pyrantel Embonate, Ivermectin, Moxidectin, Mebendazole and Fenbendazole (one of the Benzimidazole group). So look on the packet for the ingredient when buying a wormer.

Detailed instructions are included with each medicine, we therefore recommend you always read the package labelling or leaflet within the pack, before using any product. The worming drugs currently available for use in horses are extremely effective. However, horse owners should realise that individual drugs only treat certain worms and that some drugs only treat some of the life-cycle stages of certain worms.

A further complicating factor is that some worms have developed resistance to certain worming drugs. The more frequently worms are exposed to the drug, the greater the chance of resistance developing. It is not as simple as giving a dose of wormer and all the worms are killed!

See worm cycle for more information on worms.

Only two wormers can kill hibernating small red worms, Equest and Panacur Equine Guard. All worm programmes should include at least one treatment with one of these per year.

You may also find it useful to have a worm count done on your horse's droppings. These are inexpensive and will give you a good idea of how effective your worm control is.

Mares in Foal

No extra anathematic treatment is needed for the mare as long as she is included in a sensible control programme but it is always advisable to consult your Veterinary Surgeon. However, to reduce her output of worm eggs which her foal may then consume she should receive an additional dose of Ivermectin approximately 4 weeks before foaling.

Foals

It is very important to worm foals at 4-6 weeks with Ivermectin then every eight weeks, before the worms reach maturity. Do not administer Equest to young foals less than 4 months of age.

New Horses

Introduced to a yard should be wormed with moxidectin and kept in a box or restricted paddock for a two days with collection and disposal of droppings prior to any introduction to communal pasture. This should be followed by a five-day Fenbendazole course to treat any inhibited and remaining encysted small redworms present. These horses should also be blood tested for tapeworms and treated with "double-dose" Pyrantel P or Strongid P depending on the results. Monitor faecal egg counts every three months initially to ensure your programme is adequate.

Your worm control will only be as good as your grassland management. Picking up droppings in the field, daily, not allowing the ground to go ‘horse-sour’ and keeping weeds at bay are essential. Rotating cattle or sheep after the horses have grazed the land and ploughing, liming and reseeding every few years will help prevent worm infestation on the pasture.

Note: Wormers are constantly being developed and you should always consult your veterinary surgeon for personal advice for your horse in your region.

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