Equine Worming

Parasitic worms live in the intestines of all horses and ponies. In general, small numbers of worms can be tolerated but large numbers of worms can cause serious illness, such as colic, diarrhoea and serious weight loss as well as more vague illness such as a reduction in performance or a dull coat. Worm eggs can be found easily in the dung by submitting a sample to our clinic in North Kessock.

Prevention of Disease
There are two ways of preventing disease from worms: regular dosing with wormers (worming) or by using our preferred approach - and a more organic method - only worming the horses when they actually need it. Both of these approaches are detailed below but before choosing a method of control, please call us for free advice on this matter. We also provide free personalised worming programmes specific to your horse and premises.

Selective Dosing (Organic approach to worming)
We know that the main aim of a worming programme is to reduce worm eggs on pasture but most horses do not pass high numbers of worm eggs and do not need to be regular wormed: these horses are given worming medicines unnecessarily. Only a small proportion of adult horses pass worm eggs in the dung and regular dung tests can be a great alternative to worming. For this approach to be successful your grazing management must be good and dung should be removed from the pasture to prevent worm eggs from hatching and infecting the paddock. We provide excellent and free advice on this matter and can provide cost-effective dung analysis from as little as �8 per sample. We only need a small amount of dung, which can be submitted to us in a labelled small sealed bag; results are phoned or e-mailed to you within a few days and veterinary advice is always on-hand. This method of worm control is most suited to horse owners with their own premises or to well managed yards with good pasture management.

Regular Dosing (Worming)
The aim of any worming programme is to reduce the overall level of pasture contamination with worm eggs. If the number of worm eggs on the pasture is low then the level of infection in the grazing horses will be low. The most commonly used method of keeping egg counts low is to dose the horses regularly with wormers of which there are four main groups of medicines and there is more information on these below. The downside of regular worming is that most horses are receiving medicines unnecessarily and this can in itself be expensive. The biggest advantage of regular worming is that you are making sure that your horses and the grazing is as worm free as possible, with the minimum of effort.

The most important internal parasites are:

Small Redworms (Cyathostomes)
These are the most common worms and horses become infected by ingesting larvae (immature worms) from the pasture while grazing. The larvae burrow into the wall of the large bowel and �hibernate� there for years in some cases. The worms are not very susceptible to medicines whilst in this phase of their development and they cause the most damage when they emerge from the bowel wall as mature worms. As adult worms they release eggs which are passed in the dung onto the pasture and from there, hatch and re-infect grazing horses.

Large Redworms
These parasites are not very common in the UK now, but they are very serious when horses become infected with them. Large redworms, such as Strongylus vulgaris, burrow through the bowel and enter the blood stream where they cause damage, which results in life-threatening colic.

Tapeworms
Tapeworms live in the large bowel and interfere with the movement, or motility, of the large intestines. These worms are usually picked up by grazing horses in the summer and grow slowly to the stage where they cause disease. Finding tapeworm eggs in dung is notoriously difficult and a blood test is usually used to check for infection. Dosing once yearly in the autumn with wormers containing praziquantel, is sufficient to control tapeworm in the north of Scotland.

Stomach Bots
Stomach bots are becoming more common in the north of Scotland now as we are having warmer summers. A fly present in the summer, lays eggs on the coat of the horse and these develop into bots in the stomach. The bots themselves are harmless and pass into the dung in the summer where they hatch into the adult flies.

Roundworms
Roundworms, such as the ascarid, Parascaris equorum, mainly affect youngsters. The worms pass through the liver and lungs before finishing up in the small intestine. The worm eggs are very easy to find in dung samples but these worms don�t usually cause disease in adult horses. In youngsters, the signs of infection include: coughing, weight loss or poor weight gain and occasionally colic. All modern wormers kill this parasite to varying degrees.

Lungworms
The true horse lungworm is called Dictyocaulus arnfieldi. Despite donkeys being blamed for infecting horses with this worm, it really is very rare and is killed by all modern wormers very effectively.

Recommended worming programmes
Please contact us for free worming advice and a personalised worming programme.

.