Foals: Getting a head start against worms
Foals: Getting a head start against worms The birth and development of a foal is a memorable occasion, an occasion that should however be memorable for all the right reasons. |  |
Caring for the pregnant mare.
During late pregnancy the mare's natural tolerance to worms is reduced, resulting in a rise in the number of eggs in its faeces; therefore the mare becomes a significant source of pasture contamination. To help reduce this contamination as well as to help keep the mare healthy both during and after pregnancy, it is important to routinely worm using a product that is licensed for use in pregnant and lactating mares, such as EQUEST.
In addition the mare should also be wormed just before foaling, because four or five days after birth, worms often pass through the mare's milk to the foal.
Worms of particular threat to foals.
With no protective antibodies acquired during gestation, the foal's low tolerance to parasites means that it is particularly susceptible to infection. Two species of parasite of particular concern are the intestinal threadworm and large roundworm, species of parasites to which horses will develop natural immunity.
Infecting the foals soon after birth, usually via the mare's milk, these small worms - up to 1cm in length, live in the small intestine of the foal. Because the lifecycle of this parasite is very short, foals as young as four weeks of age can develop heavy worm infestations causing diarrhoea, loss of appetite and dullness. However, natural immunity is acquired at around 6 months of age.
| Large roundworms (Ascarids): Practically indestructible, the eggs of the large roundworm that contain the infective larvae are surrounded by a thick sticky outer coat. No matter how clean the stables are kept, these parasites eggs will be present. These eggs can survive for years on buckets, walls, bedding and pasture and even on the mare's udder. The main source of infection is eggs in manure: all foals eat fresh manure every few hours in order to "seed" their digestive tract with beneficial microoganisms essential for the proper digestion of vegetable matter. Infected by ingesting these eggs, the larvae of this parasite migrate through the foal's bloodstream to its liver and lungs, causing coughing, fever and loss of appetite, before they return to the small intestine. In the small intestine they develop into adults. |
These adults reach up to 40 cm in length, and can be present in the foal's small intestine from 12 weeks of age. Heavy burdens of these adult worms causes weight loss and can in rare cases result in a rupture of the gut. Natural immunity is acquired at around 18-months of age.
Damage inflicted to the foal by parasites may be gradual and subtle, with no noticeable signs from the onset. However, the foals growth and development will become impaired, its performance ability reduced, and its resistance to disease lowered - resulting in potential complications longer term. To protect the foal and give it a head start worming is vital.
| By adopting a rigorous worming programme, supported by pasture management, the risk of parasite damage to the foal can be reduced, thereby giving the foal a head start so that it develops into a beautiful, healthy horse. |
| Worming foals. The worming of foals should start at four to six weeks of age or as soon as they start to graze on pastures; with treatment being repeated every four weeks until six months old. Thereafter routine worming can be continued as per wormers' recommended dosing interval, e.g. every 13 weeks with EQUEST. With regard to tapeworm, infestation is unlikely to occur in foals under 2 months of age, so treatment of foals below this age is not considered necessary. |  |
Tapeworm is controlled by means of a double dose of a pyrantel-based wormer or with a single dose of a praziquantel-based wormer (e.g. EQUITAPE).
Important tips on worm control in foals.
- When choosing a wormer for a foal it is important to avoid drugs not licensed for use in very young foals, e.g. EQUEST should not be given to foals younger than four months of age.
- Dose the foal according to its body weight, as under dosing results in more worms surviving leading to pasture contamination, as well as contributing to the development of resistance, and overdosing can cause undesirable side effects. As the foal is developing its weight will be constantly changing, therefore, foals should be weighed prior to each treatment either by means of a weigh tape or ideally weigh scales.
- Ideally foals should not be grazed alongside older horses as foals are a major source of pasture contamination and require more regular worming.
- A paddock rotation system should be adopted so that nursing mares and their foals do not graze the same area in successive years. Ideally rotate land with sheep or cattle, as worms that affect horses are host specific and cannot survive in sheep or cattle, as such any larvae they eat will be destroyed.
- Avoid turning out young stock onto small turn out paddocks as pasture will develop extremely high larval counts particularly if droppings are not removed each day.
This article has been reproduced by kind permission of http://www.wormingyourhorse.info
Copyright: Fort Dodge
Photograph of Large Roundworm / Ascarid supplied by: http://www.wormingyourhorse.info/
Foal photographs suplied by: Voices for Horses
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Added on: 30/05/08.
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