Do you know which worms are a threat to your horse and when?Successful horse worming is a three-step journey to keep them in tip-top health and condition. If every horse owner on the planet followed these steps correctly, the ongoing battle against increasing resistance to horse wormers would be won.The golden rule is that targeted worming (ie testing horses first) rather than regular dosing of wormer can help protect your horse and the environment.The three-step journey is:Correct care and field management to prevent a worm burden;Testing at the right intervals to see whether a horse needs treating for worms rather than blanket use of a wormer;Knowing what worm is a threat when during the year.Types of horse wormsCommon parasites found in horses include:Roundworms (Ascarids)TapewormsEncysted small redwormsBotsPinworms (Oxyuris)ThreadwormsLungwormsIt is important to note, though, that it is not best practise to routinely worm around the year for all the different types of horse worms.Over-worming is a major contributor to worm resistance. Because of this, owners should always test for the presence of worms using a faecal worm egg count before worming horses, warns vet Sue Taylor. This will help decide whether a horse needs worming as it shows the presence of most egg-laying adult worms, apart from bots, tapeworm and encysted small redworm.Sue explains that faecal worm egg counts should be done at least twice during the grazing season, usually between March and September. Once you have the results, you can then decide whether or not to worm.Your vet will normally recommend that horses with a high faecal worm egg count, regular elevated counts or those who are more susceptible (such as the very young or old) should be wormed, explains Sue. Faecal worm egg counts of above 250 eggs per gram of faeces are classed as high.Annual horse worming scheduleAccording to Sue, the following is a good schedule of testing for horse worms to follow:Autumn (September October)Carry out a saliva test for tapeworm. If positive and your vet recommends treatment, target tapeworm with a wormer containing praziquantel or an elevated dose of pyrantel.Winter (November February)Target encysted small redworm with a moxidectin product. This will also kill botfly larvae. Alternatively, use an elevated dose of fenbendazole (this will not target any botfly larvae).Spring (March April)Test again for tapeworm. Do a faecal worm egg count for roundworm and, if your horse needs treating for roundworm too, use a combination wormer. Speak to your vet for advice.Summer (May August)Carry out a faecal worm egg count for roundworm and target treatment if it is necessary with fenbendazole or pyrantel.The British Horse Societys Think Before You Worm campaign, in collaboration with the British Equine Veterinary Association, was launched at BEVA Congress. Itsaim is to educate horse owners, carers and yard managers on the importance of following an evidence-based, testing-led, deworming programme that has been developed in partnership with a vet similar to the one suggested above.Effective worm managementIn order to prevent a worm burden, the way you look after your horse and their pasture are key influencing factors. Here are nine top tips for ways to protect your horse against worms:1 Weigh your horseIf a faecal worm egg count or saliva test confirms you do need to administer horse wormer, then the amount of wormer you give depends on the weight of your horse.Use a weigh tape or weigh bridge to give an accurate weight of your horse before worming. It is vital you get this right, as under-worming may be ineffective and increases the risk of worms developing a resistance to the drug.2 Poo-pick fieldsRemove droppings from grazing regularly, ideally every day but at least twice a week. This is particularly important in fields that are small and/or have multiple horses grazing them.3 Avoid over-stocking grazingAvoid overstocking paddocks with large numbers of horses. Fewer horses in a larger area (ideally allow for around 2 acres per horse) is always better.4 Rotate pastureRotate pasture so it has time to rest and recover without being grazed.5 Introduce other animalsShare horse grazing with cattle and sheep if you can. This helps reduce worm infestation because the other animalsingest worm larvae, so will act as biological vacuum cleaners. Equine worms dont develop into adults in sheep and cattle, so they wont be harmed and it will drastically reduce contamination in your field.6 Be weather wiseIf you are going to chain harrow instead of poo pick, this should be done when the paddocks are dry and hot, because once exposed to the sun, the worms will shrivel up and die. If you do it in wet conditions, they are more likely to survive. Poo-picking is a better idea.7 Choose the correct wormerNot all wormers are effective against all types of worms, so if your horse does need worming, ensure the brand of wormer you choose contains the correct active ingredients for the worms you are treating. Its the chemical group that matters, rather than the brand name of the wormer.8 Dont mix age groupsGraze young horses separately from older horses. Young horses are more likely to have the highest parasite burdens and be responsible for the majority of pasture contamination.9 Check new arrivalsCarry out a faecal worm egg count on any new horses that arrive on your yard, and wait for the results before allowing the new horse to share or use any pasture that current horses also graze.Signs a horse has wormsThe symptoms of a parasite infection in horses can vary depending on the type of worm involved and the number of worms infecting the horse. Many parasite infections will have no symptoms when the parasite burden is low, but a high number of worms can cause symptoms and will seriously affect your horses health.Being on the lookout and treating issues early will hopefully prevent serious health problems developing.Some of the symptoms to keep an eye out for include:Unexplained weight lossAnaemiaDull demeanourPoor appetiteDiarrhoea or constipationColicStaring coat (hairappears dull and is standing up)Under-par performancePatches of hair loss or sore skinParasites in droppingsHorse rubbing their bottom continuallyRespiratory problems such as nasal discharge and a coughPoor growth in foalsIf you are concerned that your horse may have a worm burden, or if you have any questions about worming, speak to your vet. Proactive testing for worms and not administering a worming drug until a tests says it is necessary, is the overwhelming advice from vets, scientists and industry experts alike.All horses need sustainable parasite control based on worm egg counts and tests to identify parasite burdens before they get to a level to cause illness, says Claire Shand from Westgate Labs. This should be done while minimising chemical intervention via wormers to slow the development of wormer resistance.Not only is this better for our horses and often cheaper too, but it also benefits the environment. Worming chemicals are poisons and each time we dose our horses, metabolites from these are passed out into the dung and onto our pastures. These leach into the soil and get washed into watercourses, causing harm to microorganisms, insects, fish and aquatic organisms.Related contentWinter worms: three to test for nowResistance to horse wormer: action every owner must take now or horses will dieWorm egg counts explainedTraditional frequent worming is unnecessary, research showsThe post When to test for worms: essential horse worming schedule from a vet appeared first on Your Horse.