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Equine parasite management

Keeping parasite levels in horses under control is highly important for maintaining overall health, and an effective parasite management programme is required to be an integral part of equine husbandry and care.

Infestations of parasites usually aren’t fatal to horses, however can cause damage to the gastrointestinal tract, which in turn can cause diarrhoea or colic. Further symptoms include a pot-bellied appearance and a rough coat, and certain parasites can adversely affect the growth of young horses. Nutritional factors are usually the first consideration made when a horse is having problems maintaining or gaining condition and often it is thought this can be solved through dietary changes. However in the case of a parasite burden, deworming the horse as needed will improve condition without changes being made in feed type or amount.

Some common intestinal worms that affect horses are the large and small strongyles (redworms), roundworms, and pinworms. Stomach bots, which are the larvae of a type of fly, are also a common type of parasite in New Zealand but these do not cause a major problem to most horses. Other parasites such as threadworms and lungworms also rarely cause problems. The common signs of worm infestation are tail rubbing, pale gums, ill-thrift, colic, and poor coats. Severe infestation can also cause diarrhoea or sudden death in rare cases.

Controlling parasites in horses is a several-step programme. Performing faecal egg counts and administering oral de-worming preparations are important, but these tasks assume that the horses are already hosting internal parasites. To make parasite control more effective, owners must also take steps to minimise parasite populations on the property and avoid re-infestation after horses have been de-wormed. Pasture management is the key to these parasite control measures.

Pasture management should be aimed at killing parasite eggs/larvae and preventing their ingestion by horses. Methods that are effective in achieving these goals are mowing fields closely before winter, rotating horses off a pasture and then cutting hay off that field before horses graze it again, rotating horses and other species (sheep or cattle) in a pasture, and harrowing to break up manure piles in hot weather and then keeping horses out of the pasture for several weeks.

Other helpful pasture management steps to minimise re-infestation with parasites are frequently rotating horses from one pasture or grazing area to another, avoiding overstocking or overgrazing pastures, and removing manure from pastures once or twice a week. Removing manure also removes parasite eggs, and composting the manure kills the eggs within a few days through the heat that is naturally produced as the manure decomposes.

Parasite control measures will vary at each equine property depending on stocking rates, other animals present and amount of land available for grazing.

For assistance with parasite management and feeding plans to enhance overall health and performance, consult with an experienced equine nutrition advisor.

Article supplied by Luisa Wood, Equine Nutrition Technical Advisor.