The threat of large round worms in horses

Large Roundworms Ascarids (Parascaris equorum)

Large roundworm

Large roundworm also known as ascarids are very long worms up to 40cm when mature and produce large numbers of tough coated adhesive eggs which can survive for several years and can stick any surrounding environment. The mature worms are white in colour and much thicker than other equine worms. The eggs can stick to the coat and udders of the mare and even to the walls and stable floors. The eggs have very thick shells and therefore can survive on pastures over the winter months and perhaps for many years .These eggs then develop into larvae (young worms) which migrate through the liver and lungs and eventually coughed up then to be ingested and subsequently maturing to egg laying adults in small intestine. This complex lifestyle creates great potential for disease can retard growth and development. Respiratory obstruction is common as a result of the presence of larval stages in the lungs.  Intestinal blockage and impaction colic is also common in foals due to the sheer physical size of the adult worms. Their presence in the gut can block the passage of food material as well as leading to nutritional deficiencies. A heavy burden of mature worms in the intestine may well give the classic signs of ill thrift, a pot bellied appearance and or sluggishness. Such a burden has the potential for fatal colic.
Large roundworm mainly affects youngsters up to 18 months old but horses with a neglected treatment history are also at risk  

SH Wetherald
E-SQP www.wormers-direct.co.uk

Correct dosing levels when worming your horse.

 A common mistake when worming horses is under dosing so ascertain the weight of your horse as accurately as you can either by using a weight tape or even better a weigh bridge. Correct dosing is important, if you under dose your horse the product will not work efficiently and could lead to resistance.

 

If you administer a sub therapeutic level of the drug and thereby expose the worms to the drug, but perhaps not at a sufficient dosage to kill them. Worms that survive treatment may pass on their “immunity” to subsequent generations and those generations will become more adept at surviving chemical treatments with the potential for resistance to develop to that drug.

There are brands on the market that now that treat up to 700kg in a single syringe and now some available in tablet form with each pack treating up to 800kg. These larger syringes and tubes give that little bit extra to play with when dosing. Many popular brands only treat up to 600kg of bodyweight so you may need to take care when working out the doses required with many horses needing more than one syringe.

When you estimate the weight of your horse remember we all lie about our weight so if in doubt, when estimating the weight err on the generous side. Although a slight overdose of wormer is unlikely to have harmful effects, as with all drugs, it is important to dose accurately and in accordance with the manufacturer’s recommendations.

SH Wetherald

E-SQP

www.wormers-direct.co.uk

Tapeworms in Horses

Tapeworms in Horses

Tapeworms belong to a group of parasites  known as cestodes (or flatworms).  Three species of tapeworms affect horses in the UK, the most common of which is Anoplocephala perfoliata (1). Tapeworms are short and flat in appearance, growing up to 8cm long and 1.5 cm wide.  They consist of a small round head which attaches the worm to the wall of the gut, and a body formed of a chain of egg containing segments known as proglottids.

Life cycle

Adult tapeworms release egg-containing body segments into the host horse’s intestine.  These are passed in the faeces and disintegrate, releasing large numbers of eggs into the environment.  Eggs are eaten by tiny forage (oribatid) mites, which can be present in very large numbers on pastures.  Over a period of approximately two to four months, these eggs develop within the mite into an infective intermediate stage of the tapeworm.  As the horses graze, they will inevitably ingest the mites, releasing the infective stage of the worm into the intestines.  The immature worm migrates to the ileo-caecal junction (the join between the small and large intestines).  Here it develops into the adult form which, after one to two months, starts to produce egg filled segments, continuing the life cycle. 

Effects of tapeworm infestation

For many years tapeworms were considered to be harmless to the host horse.  The arrival of more reliable methods for (a): identifying horses infected with tapeworm, and (b) determining severity of parasite burden (see diagnosis below) has changed this perception of tapeworm infections.  In a study of UK horses, researchers discovered that infection with the most common species of tapeworm, Anoplocephala perfoliata, increases the risk of two types of colic-spasmodic colic and ileal impaction colic. It also demonstrated that the heavier the tapeworm burden, the higher the risk of these types of colic.¹   Although the level of risk should be kept in perspective, effectively minimising  tapeworm burden should decrease the risk of tapeworm associated colic.

Diagnosis:

Diagnosing tapeworm infection can be tricky in horses. Clinical signs are not a reliable indicator, as horses can have tapeworm burdens and appear clinically healthy.  Unfortunately, counting tapeworm eggs in a faecal worm egg count (FWEC) is also unreliable, as the eggs are encased in the tapeworm segment, rather than being distributed evenly throughout the droppings.  Also, egg filled tapeworm segments are only shed intermittently.  As a result, a negative result on a FWEC does not necessarily mean a horse is free of tapeworm.

Fortunately we can use a blood sample to test for levels of tapeworm infection- a method known as the tapeworm antibody test. A horse that has a tapeworm infection will produce antibodies to the tapeworm, which can be detected in the blood.  Instead of giving the exact number of tapeworms, the test indicates the intensity of infection - the level of antibodies indicates whether the burden is low, medium or high.

While the blood test is useful for assessing whether your horse has been infected with tapeworms in the past, it is not a reliable indicator of response to treatment. This is because it takes at least 16 weeks for the antibody levels to return to normal after the worms have been killed (2).

Controlling tapeworm

As well as the appropriate use of worming treatments (see below), it is important to manage pastures carefully to minimize the parasite burden that horses are exposed to. The aim is to prevent contact with faecally contaminated pasture or feed.  This could be achieved by regular removal of faeces from pasture, prevention of over-stocking, resting heavily grazed pasture and rotating pasture with other species-eg sheep or cows. There are two different approaches to tackling tapeworm. Treatment can be targeted, following a blood test, or administered within an annual worming program.

With targeted treatment, a decision is made on (a): whether to treat, and (b): with what product. This is based on the horse’s worming history alongside combined FWEC and blood test results. Targeted treatment identifies horses which are at risk of high levels of worm infection. This helps to ensure that the most appropriate wormers are only used when necessary, thus reducing the risk of worms becoming resistant to treatment.

Using this method, horses are blood-tested for tapeworms once a year. Those with a high burden are treated after the test and then again six months later. The blood sample is then repeated the following year. New horses entering the yard should have a blood test and a FWEC to determine whether worming is required, or be routinely treated for both tapeworms and roundworms and stabled for 48 hours, before they are turned out with others.

Also new to the market is a DNA saliva test which has been developed to work like a blood test but in fact uses a simple saliva swab. For more information http://www.wormers-direct.co.uk/equisal-tapeworm-test-kit-p-286.html

In some yards, targeted worming may not be suitable or practical. In these instances, all grazing horses should be treated for tapeworms at least once yearly, and every six months in high-risk animals or those shown to have high levels of infection¹.

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There is little evidence of infection being linked to seasonality, so timing of tapeworm treatment is not critical. As risk is higher after prolonged periods of grazing, horses are often treated at the end of a summer out at grass.

It is important to be aware that not all wormers kill tapeworms. The parasites can mainly be treated with one of two drugs — praziquantel or pyrantel.  Fortunately both drugs are very effective and cause death and detachment of the tapeworms from the gut wall.  They are available as single products or in combination with other drugs that target different types of worms.  

In summary, careful pasture management combined with correct testing and treatment will ensure that tapeworm is effectively controlled. thus reducing risk of associated disease.

1.    Proudman C. and Matthews J. Control of intestinal parasites in horses.  In Practice (2000) 22: 90 – 97

2.       Tapeworm Antibody Test, Diagnosteq, University of Liverpool, http://www.liv.ac.uk/diagnosteq/tapeworm_test.htm.  Page retrieved 4^th April 2014.

Wormers-direct.co.uk are indebted to Elanco the makers of Strongid P paste for this article

Equine Pinworm - an update on how it effects your horse

Pinworm in horses

Pinworm (Oxyuris equi) burden is becoming an increasing problem for UK horse owners. Pinworm is perhaps less harmful then many parasites but more of a nuisance and an irritant as its life cycle involves laying eggs externally on the horses anus. Equine Pinworm it is becoming more difficult to eliminate. The female can grow up to approximately 10cm in length and are white in colour. They reside in the large intestine and attach themselves to the intestinal wall to ingest the contents for food.

Adults produce eggs approximately 5 months after the initial infection which are found on the pasture, in faeces, contaminated water fences and walls.

Eggs are ingested by the horse and L3 larvae are released in the small intestine, they then migrate to the large intestine to develop into the mucosa to L4 larvae which then emerge and mature into adults. The female adults then migrate from the large intestine to the anus where they lay eggs in clumps in a sticky substance on the skin causing irritation around the anus leading to tail rubbing.  These can be removed on a daily basis by cleansing the area around the tail, anus and hindquarters with warm diluted disinfectant.

On occasion the actual female worms can be seen in the process of egg laying. She can lay up to 60,000 eggs per day. The eggs are laid in a sticky substance, which is an irritant to the horse

Pinworm eggs do not show up very well on regular fecal exams because eggs tend to remain around the anus rather than being passed in faeces. Sometimes the female can be physically seen protruding from the anus in the process of laying her eggs. A skin scrape or sticky tape test in the area around the anus may be carried out by a vet.

The most common sign of pinworm infection is tail itching or rubbing. The itching is caused by the eggs being deposited around the anus. There are other things that can cause tail rubbing as well, so an itchy tail does always mean there are pinworms present. 

Active ingredients that treat for adult and pinworm larvae are Moxidectin, Ivermectin, Febendazole and Mebendazole with Pyrantel treating adults only.

Not all brands are licensed so care needs to be taken by checking the brand’s label.

The life cycle of the pinworm is longer than most other worms and immature stages of the worm are less sensitive to treatment which all in all could mean that infestations could take a year to clear up.

It was thought that older horses had a degree of natural immunity to pinworm, but infections are now being seen regularly in older horses as well as young. This change has been accompanied by a shortened time between infection and egg production, and the changing behaviour of the parasite could be causing a rise in stubborn infections. 

Extra care should be taken in the stable environment to help reduce the risk of re-contamination from buckets, feed bowls, haynets and rugs etc. Do not share grooming brushes.  A thorough clean with a heavy duty disinfectant in these areas and most importantly the stable after removing all bedding which should deposited far away from the contaminated stable immediately before it can be walked on by other horses or stable staff. Good stable cleanliness will help and is always a good idea in areas of animal care and management. Also don’t forget your own clothing as the eggs can attach themselves to gloves for example and thereby easily transferred to another part of the stable or other horses.

SH Wetherald E-SQP

Saturday, 12 April 2014

Help on hand with your horse and pet worming

My name is Simon Wetherald and I am the senior E-SQP at wormers-direct.co.uk. I am ably assisted by both my long term employee Miss Kelly Rothery who is also an E-SQP. and the rest of the team here in Leeds.

An SQP is a category of professionally qualified persons who are entitled to prescribe and/or supply certain veterinary medicinal products under the Veterinary Medicines Regulations. It is the duty of an SQP to ensure that the statutory requirements in respect of the prescription and/or supply of certain veterinary medicinal products are respected.

At wormers-direct.co.uk we have a passion for knowledge and further learning with regard to managing animal health planning and helping our clients to look after their horses and pets and welcome your calls and questions at any time.

There is a myriad of articles, ideas, theories, conclusions, speculations and conflicting advice out in the public domain about worming horses and we strive to improve our own education in these fields by conducting regular continual professional development and hopefully collating all the help and information that is out there ready to pass onto our clients.

Please feel free to contact us if you have any issues you have about worming or arranging testing your animals no matter how trivial or complicated and we will strive to answer your queries with unbiased advice.

I am lucky enough to be the Virbac E-SQP of the year for 2013 and my company trading as wormers-direct.co.uk wholly owned by myself is Bardsey Mills Ltd.

Bardsey Mills Limited is a company registered in England and Wales with company number 1024711 wormers-direct is a trading name of Bardsey Mills Limited who are member of the British Equestrian Trade Association (membership number 775) Our VAT registration number is 169 1690 34 Registered office at Unit 1E Woodside Trading Estate  Low Lane Horsforth  Leeds LS18 5NY
Wormers-direct.co.uk Ltd is a company registered in England and Wales with company number 6081924
Registered office at Unit 1E Woodside Trading Estate  Low Lane Horsforth  Leeds LS18 5NY

Call on free-phone 0800 331 7758 or if you have minutes on your mobile call free on 0333 320 0510

Pinworm in horses

Yet again 2013 is proving to be another year when equine Pinworm burden is becoming more widely reported by UK horse owners. Pinworm (Oxyuris equi) is not generally thought to be harmful as they pass through the intestine but more of a nuisance and an irritant when the female pinworm lays her eggs around the horse’s anus. The female can grow up to approximately 10cm in length and are white in colour. They reside in the large intestine and attach themselves to the intestinal wall to ingest the contents for food. Adults produce eggs approximately 5 months after the initial infection. Eggs are laid around the anus and within a few hours of being laid they develop into embryos and are infective in 4-5 days.  On occasion the actual female worms can be seen in the process of egg laying. Eggs find their way onto the pasture, into water and feed supplies, on fences, stables and walls and onto grooming kits

Eggs are ingested by the horse and L3 larvae are released in the small intestine, they then migrate to the large intestine to develop into the mucosa to L4 larvae which then emerge and mature into adults. The female adults then migrate from the large intestine to the anus where they lay eggs in clumps in a sticky substance on the skin causing irritation around the anus leading to tail rubbing.  These can be removed on a daily basis by cleansing the area around the tail, anus and hindquarters with warm diluted disinfectant The pinworm likes to emerge in the night to lay eggs so cleaning first thing in the morning is best. The recent prevalence of pinworm burden which  be in some manner due to the different strategies recently introduced involving worming horses so treating for pinworm needs to be considered when creating a animal health plan..

Active ingredients that treat for adult and pinworm larvae are Moxidectin, Ivermectin, Febendazole and Mebendazole with Pyrantel treating adults only.

Not all brands are licensed so care needs to be taken by checking the brand’s label.

Extra care should be taken in the stable environment to help reduce the risk of re-contamination from buckets, feed bowls, haynets and rugs etc.  A thorough clean with a disinfectant in these areas and most importantly the stable after removing all bedding will help and is always a good idea in areas of animal care and management. Do not share grooming brushes.

SH Wetherald

E-SQP

www.wormers-direct.co.uk

advice@wormers-direct.co.uk

0844 808 6070

Worming horses to treat for encysted small redworm

Worming experts at Pfizer Animal Health are alarmed about the results of the National Equine Health Survey (NEHS) May 2012 survey

A recent survey of horse owners has shown that nearly half are not worming their horses correctly when it comes to treating encysted small redworm. Encysted small redworm (small strongles/cyathostomes) are the most common worms found in horses today and may account up to 90% of the redworm burden in the horse ¹. The recent survey has revealed that treatment for encysted small redworm is only been done by about half of the survey respondents.

The survey which was conducted in May 2012 as part of the National Equine Health Survey (NEHS) showed that out of 1095 respondents only 505 had wormed their horse with an effective product for the control of encysted small redworm. The remainder had either used a product that they thought treated encysted small redworm when in fact it did not or they simply did not worm their horse or pony at all. The most common reason for not treating for encysted small redworm was that the horse had had a clear faecal egg count.

“Encysted small redworm won’t show up in a standard faecal worm egg count – even if the horse has shown a negative or low count it could still be harbouring several million encysted small redworms ², which can present a potentially fatal health risk to the horse” says Wendy Talbot Pfizer’s vet advisor.

Encysted small redworm can remain dormant inside a horse for up to 2 years, but usually develop and emerge from the gut wall all at the same time in the early spring. In severe infestations mass emergence can lead to a disease syndrome known as “Larval cyathostominosis” causing diarrhoea and colic with up to a 50% mortality rate³.

It is most important to use a wormer containing moxidectin or a 5 day fenbendazole course licensed to treat encysted small redworm. It is important to remember that there is now widespread resistance to fenbendazole in parasite populations⁴, whereas moxidectin has been shown to be effective against benzimidazole resistant worms and has a 13 week recommended dosing interval

1          Bairden K. et al (2001) Veterinary Record 148, 138-141
2          Dowdall S. et al (2002) Veterinary Parasitology 106, 225-242
3          McWilliam H. et al (2010) International Journal for Parasitology 40, 265-275
4          Matthews JB (2008) An update on cyathostomins: Anthelmintic resistance and worm control. Equine Vet. Education 20 552-560