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Worming programmes There are many considerations that affect one’s choice of worming programmes such as: • grazing history of the pasture, • stocking density - ideally 1 – 2 horses per acre, • the ages and worming history of the horses grazing together – young and very old horses often carry higher worm burdens, • the level of co-operation between owners – grazing groups of horses should be treated identically. Pasture Management One of the easiest ways to prevent a build up of the number of eggs and infective larvae on the paddock is to regularly remove droppings. This has the added benefit of increasing the grazing area available as the droppings don’t ‘sour’ the grass. The best policy is daily removal although once or twice a week is also effective. In warm, sunny weather the pasture can be harrowed to spread and dry the droppings to kill the larvae,but this can have the detrimental affect of spreading parasitic infection to all the grass in warm and damp conditions and is really not recommended in the UK unless a prolonged hot dry spell of weather can be garanteed. =If possible other types of animals (such as sheep or cattle) should be allowed to graze on the pasture, as they will not be infected by horse worms and will be happy to eat the rough or ‘soured’ areas. Although strongyle (redworm) larvae can survive over winter and ascarid eggs can remain viable for years, resting fields can also reduce contamination. If clean pasture becomes available, horses should be dosed effectively and then stabled for 2 – 3 days to allow any eggs in their system to be passed before moving fields. Wormer Choice There is a wide choice of wormers (anthelmintics) on the market. No wormer is effective against all worm types; a combination of treatments based on test results should be used. Choice therefore depends on whether it is being used to treat a specific problem or as part of a routine control programme. Worm egg counts should be done several times during the first season of a worming programme on all the horses in a grazing group to ascertain the level of risk. If the egg count is low or negative it would be wise to discuss the treatment intervals with your vet as this will depend on several factors. The need for tapeworm treatment can be identified with an annual blood test which means that susceptible horses can be identified and unnecessary treatments avoided. Your vet is the best person to ask for advice as he/she will be familiar with your situation and also be aware of any local problems of resistance to a particular medication. To see our worming table please Click Here. Worming interval There are three different ways of using worming preparations: • Interval dosing - treatments are given at the manufacturers recommended intervals through the year. • Strategic seasonal dosing - wormers are dosed through the grazing season three times but this can be a hit or miss system. • Targeted strategic dosing - horses with worm egg counts (wec) of more than 200 eggs per gram are wormed at specific times of the year. At one point in the year a larvicidal treatment should be given, usually in November. General Rules for Worming • Every horse in the field should be wormed with the same product at the same time unless worm egg counts/tapeworm blood tests show that individuals do not require treatment. • It is essential that each horse receives the correct dose based on bodyweight. • A record should be kept of the product used and the date given. • New horses should be tested and then given a larvicidal drug and kept in for 3 days before being allowed onto pasture. • Foals should be wormed with some preparation from 4 weeks of age. • Mares should be wormed when they return from stud and one month before foaling. Testing Regular Diagnostic Testing should be used to monitor the efficacy of the programme. This is a cost-effective way of determining whether horses actually require treating for worms. It can also be used once or twice a year to check that worm control programmes are working. There are two tests currently used: • Faecal worm egg counts. This simply requires you to submit a small (a teaspoon sized amount will be sufficient) labelled sample of fresh droppings to your vet or lab for analysis. This will assess the number of worm eggs present, which is useful for checking the parasite status of a particular horse and deciding whether or not it needs treatment. A result of less than 200 eggs per gram is acceptable and usually indicates that treatment is not required. It is sensible to tolerate low levels of worm infection, which are not harmful to your horse and may stimulate their natural immunity. • A blood sample can be taken by your vet and sent for a specific antibody test for tapeworms. Routine worm egg counts do not detect tapeworms, so blood samples are a useful to screen healthy horses as well as those with recurrent colic; see www: diagnosteq.co.uk .It is best to take samples just before the horse is due to be wormed. Paste or granules? Both types are equally effective. Granules are often cheaper and can be added to the feed although fussy feeders may not consume the whole treatment. Paste is usually quick and easy to administer. WARNING! Moxidectin and ivermectin can have severe adverse affects on dogs and cats. Keep syringes safely and make sure these animals have no access to feeds containing the paste or the droppings of the horse for 3 days after worming. Wherever possible, administer the paste directly into the horse’s mouth. Moxidectin can also be toxic to horses if overdosed – this is most likely to happen in foals and Shetland ponies / miniature horses IT IS ADVISEABLE THAT A VET CHECKS THE WORMING PROGRAMME AT LEAST ONCE A YEAR SINCE TREATMENTS, PROCEDURES AND PARASITES CONTINUALLY CHANGE. |
