Equine Science UpdateReports from the world of equine research Autumn 2008

It has long been stated that having along stride is a prerequisite for a goodracehorse. But is stride length thatimportant?

Do horses that walk with a longstride necessarily have long strideswhen galloping? And do successfulracehorses have different stride char-acteristics at exercise than lesssuccessful ones?

It is easy enough to measure stridelength at a walking pace - the distancebetween successive imprints of thefeet can be measured. But at higherspeeds it becomes more difficult.

3D-motion analysis equipment canproduce accurate measurements. Butthe equipment is expensive and time-consuming to set up. It is also limitedin that, at most, only two or threestrides can be captured on the videorecording.

Accelerometers that recordmovement in three planes are nowavailable. When combined withglobal positioning system (GPS)devices, they allow the horse’s speedand stride length to be recorded whileit is galloping.

At the Conference on Equine SportsMedicine and Science, held inUtrecht, the Netherlands, recently,Dr Jeremy Naylor, racehorse trainerand veterinarian, and Debbie Holmesof the Equine Sports Medicine Centreat Bristol Vet School, described theirexperience with a commercialaccelerometer system (“Pegasus”)*.

The system comprises an accelerom-eter mounted on the withers and aGPS module mounted on the jockey’shat. Information is downloaded to a

computer, which calculates speed,stride frequency and stride length.

Debbie Holmes described the initialstudy to validate the use of the system.Six fit Thoroughbred racehorses wereexercised at two speeds (11m/s and16m/s) on a wood chip track. Datafrom the accelerometer werecompared with manual readings.Stride length was determined bymeasuring the distance between eachsuccessive lead footfall over onefurlong (1 furlong = 660 feet or201.86 metres) in the middle of thegallop. The horses’ speed wascalculated using a stopwatch.

The accelerometer system proved togive accurate results. The researchersfound no significant differencesbetween the results obtained with theaccelerometer system and the manualmeasurements.

Dr Naylor described a further studythat compared three standard exercisetests to see which was the mostappropriate for measuring stridecharacteristics. He found littledifference between the three tests.However, the most repeatable resultswere obtained using a two stepconstant speed test. (Horses wererecorded running first at a constantspeed of 8m/s, followed by a secondgallop at 17m/s)

There was a wide variation betweenhorses. “We did find there to beconsiderable variation in theindividual horse’s characteristics inhow they got different stride lengthand stride frequency to achievedifferent speed of exercise.”

Having demonstrated that thesystem provides a reliable andpractical method of recording stridedata of horses travelling at speed,Dr Naylor plans to broaden the scopeof the research. By involving othertrainers he hopes to examine therelationship between stridecharacteristics and performance inracehorses.

Further research could also look athow training or fatigue affects stridecharacteristics, and the effect of therider on the way the horse goes.

*Pegasus Stride System. EuropeanTechnology for Business Ltd.http://www.etb-pegasus.org

Measuring stride characteristics.

Equine Science Update2

Technological training.

Collaboration between Turkish race-horse and camel training equipmentcompany Kurt Systems and UK-basedperformance engineering specialistsRoush has resulted in a mobile race-horse-training vehicle. Could this bethe shape of things to come?

This mobile race trainer offers amoving enclosure in which a horse (orcamel) can walk, trot or gallop (up to60km/h) in a controlled environment.

Gallop speeds can be preciselycontrolled, based on heart ratemonitoring or post exercise bloodlactate measurements.

The vehicle consists of a cab with acentrally mounted driver’s seat. Twoextra seats allow the trainer andveterinarian to travel with the horse.

The horse is held between twobeams, in front of the cab.

Electronically operated reins guide thehorse in the same direction as thevehicle. The vehicle carriessophisticated equipment to monitorheart and respiratory function and gait.It is, in effect, a mobile exercisephysiology laboratory.

Like a treadmill, the system can set aconstant speed for the animal to work -individually selected for each animal.But, its creators point out that with this

Equine Science Update 3

Horse wormer study - help needed.

What are the most effectivestrategies for controlling worms inhorses? Do we rely too heavily onchemical wormers? Are beneficialmanagement practices usedeffectively? Generally, little isknown about the approach to wormcontrol throughout the country.

A research project at theUniversity of Reading aims to findout about the general patterns ofequine wormer use in the UK. Suchinformation is important whenstudying the development of resist-ant strains.

The project includes a nationwidesurvey of worming practices.Horses owners are encouraged totake part by completing a shortonline form.

The research is being carried outby the Veterinary Epidemiologicaland Economics Research Unit(VEERU) at the University. TheVEERU researchers have expertknowledge of the science ofepidemiology, which seeks toexplain the behaviour of a particu-lar disease in a population ofanimals.

Scientists acknowledge thatcurrent strategies used to controlintestinal parasites (helminths) inhorses are not sustainable. This ismainly because of increasingresistance to pharmaceuticalwormers, which is made worse bythe inappropriate use of wormersand under-use of beneficialmanagement strategies.

Lead researcher, Keith Allison,says "this new study will enable abetter understanding of the problemof resistance to pharmaceuticalwormers. The outcomes from theresearch will help us to provideimproved information for horseowners about the most effectiveapproach for them in order tocontrol helminth infections.”

In addition to the survey, theresearch also involves laboratoryanalysis to determine thesusceptibility of the parasites tovarious chemical compounds.

To take part in the survey, followthe link from the VEERU homepage (www.veeru.reading.ac.uk) toa short anonymous questionnaire.

system the horse can run on its normalworking surface - even on the race-course.

A question that occurs to most peopleis, what happens if the horsestumbles? Surely a four-tonne trucktravelling close behind must presentsome risk to the horse? Apparently not.The horse is supported in the shafts ofthe vehicle by a band, which isanchored at four points.

You want to exercise more than onehorse at a time? Kurt Systems havealso developed a rail system - wherea train of horse stalls is suspendedfrom an overhead monorail. “With therail system you can train up to 50horses simultaneously, using a maxi-mum of three or four people to over-see the entire convoy.”

Kurt Systems General Manager,Daniele Camuffo says, “We believethat our approach to controlledenvironment training will becomeestablished practice with many studsand stables at this level”.

For more information see:

http://www.kurtsystems.com

Equine Science Update e-news is now available.Receive monthly news by e-mail

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Equine Science Update4

Just when it seems that the role of tape-worms in colic is becoming clearer,along comes a study that producesconflicting evidence.

Dr Lise Trotz- Williams and others atthe Ontario Veterinary College inGuelph, Canada, examined the level oftapeworm ELISA antibodies in horseswith and without colic. They also lookedfor tapeworm eggs in the faeces.

Over half (56.4%) of the horses testedpositive for the presence of tapewormELISA antibodies. In contrast only 6%of the horses had tapeworm eggs in thefaeces.

Horses that depended on pasture formuch of their food were six times morelikely to have high tapeworm ELISAlevels.

So far so good. However, when theylooked at the relationship between tape-worm antibodies and colic they found noevidence that higher tapeworm antibodylevels increased the risk of colic. In fact,they found that horses with a mediumELISA optical density (>0.2- 0.6) wereactually at lower risk of colic than horseswith low optical density (<0.90).

This is at odds with the previousstudies in the UK (1) and the Netherlands(2), which showed that the risk of colicincreased with higher tapeworm anti-body levels.

However the authors of the report pointout that their work does not refute thefindings of the previous studies. Theysuggest possible reasons for the differ-ence.

Their study involved horses with mildcolic treated on a first opinion basis byveterinarians in Ontario. In contrast theprevious studies involved more narrowlydefined cases examined at a referralhospital.

There were also differences in the studydesign that may have contributed to thedifference. For example nearly all thehorses in the Ontario study werematched with control horses from the

same stable for statistical analysis. Onlyabout half of the cases in the UK studywere matched with horses from the samestable. No attempt was made to matchcases with horses from the same stablesin the Dutch study.

However the authors to suggest that thefindings question whether tapewormsplay a role in cases of colic that aretreated on a first opinion basis by veteri-narians in Ontario.

For more details see:

Occurrence of Anoplocephala perfoliatainfection in horses in Ontario, Canadaand associations with colic and manage-ment practices.L Trotz-Williams, P Physick-Sheard, HMcFarlane, D L Pearl, SW Martin, ASPeregrine.Veterinary Parasitology (2008) 153, 73 -84.

(1) CJ Proudman, NP French, AJ Trees.(1998) Tapeworm infection ins a signif-icant risk factor for spasmodic colic andileal impaction colic in horses. Parasi-tol. Today. (1998) 15, 156- 159.

(2) M Boswinkel and MM vanOldruitenborgh-Oosterbaan. Corre-lation between colic and antibody levelsagainst Anoplocephala perfoliata inhorses in The Netherlands. Tijdschr.Diergeneeskd. (2007) 132, 508-512.

Do tapeworms cause colic?

Researchers in Scotland are workingto develop a blood test for small redworms.

Cyathostomins (the small strongylesor small red worms) are an importantcause of intestinal disease in horses.

Typically, larvae taken in by the horseduring the late summer and autumn donot complete their life cycle that year.They burrow into the wall of the largeintestine where their further growth isinhibited. Apparently healthy horsescan carry a heavy burden. As theyhibernate in the gut wall, thecyathostomin larvae are a diseasewaiting to happen.

Later, usually in early spring, theseencysted larvae may emerge en massecausing significant damage to theintestinal wall. Paradoxically, this canoccur just after the horse is treated withan anthelmintic. Mass emergence ofthe larvae leads to chronic diarrhoea,weight loss and loss of appetite.Obvious signs of disease are mostcommon in younger animals.

As it is the larval stages that areinvolved, they produce no eggs and areundetectable in faecal tests. They arealso invisible to current blood tests.This means that often the firstindication of a problem is when thehorse becomes ill.

Once the horse shows signs of diseaseit is usually possible to find the smallred worms in the faeces. However,there is currently no way to identifythose horses that have a heavy burdenof inhibited larvae and so are at risk ofdisease.

It is their ability to hide in the gut wallthat makes the cyathostomins sodangerous. By the time signs of disease

Blood test forsmall

redworms.

Tapeworms attached to the gut wall.Photo courtesy Ontario VeterinaryCollege

Equine Science Update 5

are shown it may be too late to treat theanimal effectively.

So a means of detecting thecyathostomin larvae before they cancause damage would be very useful.Work to develop such a test has beengoing on at the Moredun ResearchInstitute in Scotland.

Previous work has identified twolarval antigen complexes that might beuseful for detecting cyathostomins inthe gut wall. Hamish McWilliamdescribed recent efforts to build onthat work at the 9th International ColicResearch Symposium. He and hiscolleagues have been using molecularbiology techniques to identify thegenes in the cyathostomin DNA that isresponsible for producing the proteinsin the antigenic complexes.

To start with, possible candidategenes were narrowed down byselecting those that reacted to serumfrom cyathostomin-infected ponies.Then those that reacted to serum fromnon-infected ponies were rejected.Twenty-nine genes were left. Thescientists have been looking at those,and the proteins they produce, to seewhich would be most suitable for useas a test for inhibited cyathostomins.

They have checked whether theyshow cross-reactions to largestrongyle or other worm proteins, andare now assessing them against serumtaken from horses with different levelsof cyathostomin infection. This shouldallow them to choose the proteins thatare most likely to be useful in adiagnostic test.

There is still some way to go before atest is available, but we are heading inthe right direction.

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Thursday 13th November 2008Cheltenham Racecourse

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How accurate are wormtests?

The faecal worm egg count is acommon procedure for investigatingintestinal parasitism in horses.

A sample of faeces is taken, suspend-ed in liquid and the eggs in a smallamount of the liquid are counted.Unless the worm eggs are distributedevenly throughout the faeces, then theresult may not accurately reflect theegg output of the horse as a whole .

Matthew Denwood , working in theFaculty of Veterinary Medicine at theUniversity of Glasgow has beenlooking at the factors that affect thisvariation in accuracy.

Five stabled horses were tested overa week. Faeces samples werecollected morning and afternoon .

A McMaster slide was used forcounting the eggs. Normally the resultis calculated after counting the eggsin only one or two chambers. For thisstudy, Denwood recorded the eggspresent in ten chambers.

Two horses were also tested moreintensively. A single faecal ball and afaecal pat were each tested five times.

Denwood found considerablevariation between tests on the samehorse. For example, one animal gavecounts ranging from 100 eggs pergram (epg) to 850epg (average454epg) from the same pile of faeces.If only a single test had been used todetermine if the egg count were highenough to require anthelmintic

treatment, it would have been wrong25% of the time.

Although he did not specifically testfor changes in worm egg countthroughout the day ( there were notenough samples) he found noevidence to suggest there was adiurnal variation.

Most of the variability (around 74%)was due to differences betweenanimals. Differences between samples(from the same horse) accounted foraround 13% of the variation. Thecounting process itself wasresponsible for only around 4% of thevariability - when the result was basedon counting10 McMaster chambers.However this rose to around 11%when only one chamber was counted.

Denwood concludes that repeat-ability of faecal egg count testsappears to be poor because ofvariability between animals andbetween samples .

How can you make the faecal eggcount more closely reflect the actualworm egg output of the horse? Hesuggests counting more chambers andreducing the variability of the sampleby including more homogenisedfaeces in the sample examined.

Equine Science Update6

Preventive antibiotic treatment mayhelp reduce the number of cases of foalpneumonia caused by Rhodococcusequi, according to a recent report.

Rhodococcus equi (R equi) causesabscesses in the lungs. Affectedanimals show signs of fever, cough,rapid breathing, and nasal discharge.The disease tends to developinsidiously. Few signs may be apparentuntil the disease is quite advanced. Theorganism is often found in soil,particularly in dry dusty conditions.

Typically the disease occurs in foalsup to 6 months old. However, it seemslikely that foals actually pick up theinfection in the first few days or weeksof life. The organism is able to liveinside the cells (alveolar macrophagesand neutrophils) that are supposed todestroy it. This presents an addedproblem for treatment, as it is necessaryto use an antibiotic that can get intothese cells to reach the bacteria.

The disease may be well advancedbefore it is diagnosed, makingtreatment more of a challenge.Treatment is expensive and prolonged.A combination of two antibiotics, amember of the macrolide class (such aserythromycin, azithromycin orclarithromycin) and rifampin, isgenerally effective but may need to begiven for up to 1 - 2 months.

Certain farms seem prone to R equiinfections, and have affected foals yearafter year. What can they do to preventfurther cases? Intravenous hyper-immune plasma can be used. But it isexpensive and labour-intensive. Novaccine is currently available.

Would a course of antibiotics in thecritical first few days of the foal’s lifeprevent the infection from becomingestablished? Research workers at theCollege of Veterinary Medicine andBiosciences, Texas A & M University,conducted a study to examine theprotective effects of giving foals azi-

Preventing foal pneumonia.thromycin every other day for the firsttwo weeks of life.

As well as being effective againstR equi, azithromycin reaches highconcentrations in the alveolar macro-phages and neutrophils. It is absorbedwell after oral administration in foals

The researchers chose farms that hadsuffered infection rates of more than20% over the previous two years. Thestudy was limited to foals that stayedon the farm from birth to 150 days ofage. Foals that were born on the farmand moved off, or that moved onto thefarm after birth were excluded. Manyof the foals (in both groups) alsoreceived prophylactic hyper-immuneplasma.

Foals were assigned randomly to atreatment or control group. The treatedfoals received azithromycin every 48hours until they were two weeks old.Participating farms and veterinarianswere not blinded as to which treatmentgroup foals were assigned to.

Overall, 13% (44) foals developed Requi pneumonia. Azithromycin-treatedfoals were significantly less likely tobe affected than were the control groupof foals. Only 5.3% of treated foalsdeveloped R equi pneumoniacompared with 20.8% of the controls.All but one foal responded to treatmentand made a full recovery.

No significant adverse effects of thetreatment were reported.

One danger of using prophylactic anti-biotics is the risk of encouraging thedevelopment of resistant bacteria. Theresearchers checked faeces andtracheal aspirates from both groups offoals and found no evidence of R equiresistant to azithromycin. However itwas beyond the scope of the study tocheck for resistance developing inother species of bacteria.

They also found that treated foals hadlower concentrations of R equi in thefaeces. They suggest that this findingneeds further investigation. If it ispossible to reduce the excretion of theorganisms that may help to reduce theenvironmental contamination - whichmay reduce the risk of infection inlater years.

The authors of the report concludethat this was an effective strategy forreducing the cumulative incidence ofR equi pneumonia cases. It alsoreduced the faecal shedding of R equi,which may have reduced thecontamination of the environmentwith the organism.

However, although they foundbeneficial effects, and no evidence ofresistance, they DO NOT recommendwidespread use of azithromycin forprevention of R. equi, because of therisk of promoting antibiotic resistance.Since azithromycin is currently one ofthe few antibiotics effective for treat-ment of affected foals, the authors donot encourage the use of it forprevention. This study providesevidence that preventative measurestaken early in life can reduce theincidence of R. equi pneumonia.Further studies are needed to developother preventative measures duringthe early weeks of life.

For more details see:

Chemoprophylactic effects of azithro-mycin against Rhodococcus equi -induced pneumonia among foals atequine breeding farms with endemicinfection.MK Chaffin, ND Cohen, RJ Martens.J Am Vet Med Assoc (2008) 232,1035 - 1047.

Equine Science Update 7

Effect of light on loading.steps the horses took before goinginto the trailer.

Generally, the horses showed anincrease in heart rate as they wentinto the trailer. However, this changein heart rate occurred irrespective ofthe lighting conditions.

Although the horses showed nosignificant differences in time takento load, they did show signs of uneasewhen loading under certain lightingconditions. When loaded from a well-lit arena they were more likely to turnaway from the trailer or lower theirheads than when loaded from an unlitarena.

And when loading from a well-litarena into a dark trailer they sniffedthe ground more.

The researchers suggest that horsesleaving a well-lit area and entering aconfined dark space needed to ex-plore the environment more.

They suggest that avoiding suchlighting conditions may help reducestress on horses during loading. As aconsequence it might be possible toreduce the risk of injury to horse orhandler.

For more details see:

Effects of lighting conditions on thewelfare of horses being loaded fortransportation.N. Cross, F van Doorn, C Versnel, JCawdell-Smith, C Phillips.Journal of Veterinary Behavior(2008) 3, 20 - 24.

Does the lighting inside or outsidethe trailer make any difference to thehorse’s willingness to load?

Loading horses for transportationcan be a stressful experience both forthe horse and the handler. Anythingthat can be done to encourage thehorse to load easily would bewelcome.

A study conducted by Dr NicolaCross and colleagues at theUniversity of Queensland, Australia,investigated the influence of lightingconditions inside and outside thetrailer on the horse’s response toloading.

Eight yearling horses took part inthe study. They had been trainedpreviously to enter a trailer inresponse to a friendly human voiceand gentle scratching of the neck.Hay was given as a reward when theysuccessfully entered the trailer.

For the study, the trailer waspositioned in an arena. A woodenramp led into the trailer. Straw wasplaced on the ramp and in the trailer.Two 500-watt lights were arranged;one in the arena and one inside thetrailer, so that either or both could beilluminated.

The handler stood at the bottom ofthe loading ramp, gave a sharp tug onthe horse’s head collar towards thetrailer and then released the horse.

The researchers monitored the heartrates of all the horses as they wereloaded into the trailer. They alsomonitored the horses’ behaviourduring the loading process.

They found that the lightingconditions inside and outside thetrailer had no significant effect on thetime taken to load the horses. Neitherdid the lighting affect the number of

Equine Science Update8

How important is eye contact.

Eye contact may not be as importanta factor in catching horses aspreviously thought, according to arecent report. The study, conductedby Sarah Verrill and Dr SueMcDonnell at the University ofPennsylvania School of VeterinaryMedicine, looked at whether horseswere caught more easily if the catchermaintained eye contact with them ornot.

Two separate groups of horses wereused in this study. The larger groupcomprised a herd of seventy-foursemi-feral Shetland ponies that livedat the University’s New Bolton Cent-er. Most of the ponies had been bornthere. Other than a thirty-minutehandling session that they receivedduring the first two months of life, theponies were handled onlyoccasionally.

The remaining horses were ofvarious breeds and ages, and hadbeen trained in disciplines such asracing, showing or pleasure riding,before being donated to theUniversity. Most of these horseswere regularly handled.

caught within 3 minutes, the attemptwas considered unsuccessful.

Verrill and McDonnell found nosignificant difference between eitherapproach, in either the semi-feralponies or the well-handled horses.Even when the results were analysedseparately for semi-feral stallionsand mares there was no significantdifference in response to eye contact.

“There was clearly no difference inoutcome when maintaining oravoiding human-horse eye contactwhen attempting to catch horses andponies in an open pasture” theyreport.

So the results do not support thesuggestion that human-horse eyecontact is an important influence oninteractions between humans andhorses.

However, this study involved a onehandler and one handling scenario.Further work, with a variety ofhuman handlers, and involvingdifferent handling scenarios isrequired to better understand the roleof eye contact in human-horseinteractions.

For more details see:

Equal outcomes with and withouthuman-to-horse eye contact whencatching horses and ponies in anopen pasture.Sarah Verrill, Sue McDonnellJ Equine Vet Sci (2008) 28, 309 - 312.

The study was conducted with thehorses on their normal pasture andwith their usual companions. Thehorses and ponies were divided, atrandom, into two groups. Horses inthe first group were approached withhuman-to-horse eye contact. In thesecond group, eye contact wasavoided.

All attempts to catch the horses weremade by the same person, who wasmoderately experienced in pleasurehorse management, includingcatching horses at pasture. She hadpractically no previous contact withthe horses involved in the study.

A standard procedure was used totry and catch each horse. The handlerapproached to about 5m from thehorse at a relaxed walk carrying onlya lead rope.

At that point, she either made hardeye contact with the subject by focus-ing directly on the face and eyes ofthe horse (eye contact group) whilstwalking towards the horse’s shoulder.Once the catcher reached the horse’sshoulder, she caught the horse byclipping the rope onto the head collar,or in the case of the semi-feral ponies,looping the rope around the neck.

For the non-eye-contact group theapproach was similar except that thecatcher’s eyes were directed towardsthe horse’s body rather than the face.

The procedure was repeated on thesemi-feral ponies a month later withthe approaches reversed - so that theresponse of all ponies to being caughtwith or without eye contact had beenassessed.

The time to catch each horse wasrecorded - typically taking about halfa minute. If the horse could not be

Equine Science Update 9

Dozing sign of satisfaction.

press the button twelve times to receivethe reward they tended to spend moretime investigating the bedding. Incontrast, when they had to press onlythree times they spent more timedozing in standing sleep. Thescientists did notice that age affectedthe time spent dozing. Older horsesspent less time dozing than didyounger ones.

The researchers conclude thatstanding-sleep is a behaviouralindicator of eating satisfaction. Theysuggest that it may be a usefulindicator that the welfare conditions ofthe horse are satisfactory. However,they advise that it is necessary toconsider the horse’s age when usingstanding-sleep behaviour as anindicator of satisfaction.

For more details see:

A note on a behavioural indicator ofsatisfaction in stabled horses.S Ninomiya, S Sato, R Kusunose, TMitumasu, Y Obara.Applied Animal Behaviour Science(2007) 106, 184 - 189.

A dozing horse has eaten enough,according to recent research.

What behavioural signs do horsesshow when they have eaten enough?

A Japanese study has beenobserving the behaviour of stabledhorses to identify indicators ofeating satisfaction. ShigeruNinomiya and colleagues trainedsix horses to press a button, whichthen dispensed a food reward. Itdidn’t do this every time, but wasprogrammed to do so after beingpressed either three or twelve times.

The study ran for four days. Eachhorse spent an hour in anexperimental stall, which containedthe button and food dispenser. Ontwo days, the horses received foodafter pressing the button three times.On the other days the horses had topress the button twelve times beforefood was dispensed.

As well as recording the number ofrewards each horse obtained duringthe experimental period, theresearchers recorded and monitoredhorses behaviour and heart rate.

Horses that were rewarded afteronly three presses received morefood than those that had to press thebutton twelve times.

As it took more time and effort forthe horses to receive food whenthey had to activate the buttontwelve times, it is likely that underthose conditions they were stillhungry. In contrast, the horses thathad pressed the button only threetimes were more likely to feelsatisfied.

The scientists compared the horsebehaviour under the two conditions.They found that when horses had to

Equine Science Update10

Progress towards a blood test for ragwort.Scientists at the Faculty of

Veterinary Science at LiverpoolUniversity have reported the initialresults of their search for a test forragwort poisoning in horses.

Ragwort (Senecio jacobea - alsoknown as tansy ragwort) is widelybelieved to be the most common causeof liver disease in horses in the UK.

Its yellow flowers are often seen onroadside verges, railwayembankments, wasteland and poorlymanaged pasture. The fresh plant isunpalatable, so horses are most likelyto eat it when it is present in hay. Itcontains several pyrrolizidinealkaloids (PAs) - including jacobine,erucifoline and senecionine. Afterbeing eaten, these PAs are metabolisedin the liver to become pyrroles, whichare toxic.

The pyrroles react with DNA in theliver cells, leading to cell damage.They can also escape into thecirculation where they react with thesulphur-containing thiol groups inblood proteins.

The toxic effects are cumulative.Poisoning occurs slowly - signs ofdisease may appear only long after theragwort is eaten. However, onceclinical signs appear, the damage tothe liver is usually so severe thattreatment is ineffective. Estimatessuggest that, in the UK alone, ragwortmay be responsible for 500 or moredeaths in horses and ponies each year.

The researchers at LiverpoolUniversity have been trying to identifychanges in blood proteins caused bythe toxic pyrroles. Such alteredproteins could act as markers toindicate recent ragwort consumption.Their aim is to develop a test toidentify the by-products of the ragworttoxins in a blood sample.

In this laboratory study, theresearchers used monocrotaline, apyrrolizidine alkaloid closely relatedto those found in ragwort, which iscommercially available. The mono-crotaline was chemically treated tomimic the process of metabolism thatthe PAs undergo in the liver. Theresulting toxic pyrrole (called dehy-dromonocrotalin or DHM) was mixed

with samples of horse plasma, and theresearchers studied the changes in theblood proteins that occurred.

The first possibility they consideredwas haemoglobin, the main oxygen-carrying molecule, found in the redblood cells. It is a large molecule, andcontains thiol groups, and so mighthave been expected to show character-istic toxic damage.

They incubated normal equinehaemoglobin, with differentconcentrations of DHM. Then theyanalysed the haemoglobin for signs ofchanges, but could not find any.

So they looked at other potentialtargets for damage with pyrroles -other proteins.

They found that when DHM wasadded to the plasma protein anaggregate in the high molecular weightregion was formed. This aggregatewas only found when DHM was addedto the protein. It was not found if either

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Equine Science Update 11

For all trainers and breeders –indeed anyone involved in the worldof racing – the 2008 ThoroughbredRacing and Breeding Seminar is anabsolute must-attend event.

Since its was first held eight yearsago, the annual Seminar has gonefrom strength to strength, become alandmark in the horseracing diary,and has consistently drawn the mostauthoritative speakers and the mostknowledgeable audience. The Semi-nar aims to communicate in apractical way, the results of scientificresearch, and so benefit the welfareof Thoroughbred racing andbreeding horses.

This year’s event promises to be thebiggest and best so far, showcasingnot just the latest research andcutting edge technology, but also theultimate in practical, up-to-the-minute information, all presented inan entertaining format.

The Seminar will be held onThursday, 13th November in theimpressive Centaur conference andexhibition space, at the heart of theCheltenham racecourse, the home ofBritish jump racing .

Two new features have beenintroduced this year. Kicking off theprogramme will be a fast-pacedNews Bulletin, in which Dr. PeterWebbon, Seminar Chairman andAnimal Health Trust Chief Executive,and highly regarded equine specialistMr. Geoff Lane, will present an over-

Thoroughbred Racing and BreedingSeminar

view of ‘stop-press’ news from theequine veterinary profession.

Immediately after lunch, theaudience can quiz a panel of expertson all aspects of equine veterinaryscience (questions can be submittedvia the website ahead of the eventbut can also be accepted on the day).

The themes this year includeimmunology, with Professor DerekKnottenbelt, specialist in EquineOncology, providing an overview ofhow the equine immune systemworks and how it can be enhanced,and Nick Wingfield Digby ofBeaufort Cottage Stables, speakingon immunity in young foals.Professor Knottenbelt will alsodiscuss best practice in the treatmentof wounds.

Professor Tim Morris from theBritish Horseracing Authority(BHA) will give details of a majorstudy into the genetic basis of certainequine conditions.

Professor Alan Wilson of the RoyalVeterinary College, London, and Dr.Sam Franklin of Bristol University,will give an extraordinary insightinto the highly advanced technologynow being used to monitor horseswhile they are working, highlightingthe latest sophisticated videoanalysis and sound recording proce-dures.

For a registration form, or for moredetails, visit:

www.thoroughbred-seminar.co.uk

monocrotaline (the PA itself beforebeing metabolised to the toxicmetabolite DHM) or the solvent wereincluded in the reaction mixture

They identified the proteins in theaggregate - serum albumin, fibrinogen,transferrin and IgG.

The next step was to check thereaction of DHM with albumin, fibrino-gen and transferrin individually.Fibrinogen, in particular, formed highmolecular weight aggregates whenmixed with DHM.

These toxic changes in fibrinogencould be detected by techniquesregularly used in diagnosticlaboratories. So this test could be easilyperformed in commercial laboratories.

Ragwort is recognised as a threat tohorses. Without a specific way ofidentifying exposure to the toxin it isimpossible to assess the true level ofthreat. The discovery that fibrinogen ismodified by the toxic pyrrole is the firststep towards a specific test for ragwortpoisoning.

Perhaps the greatest benefit of such atest would be to allow owners to checkthat the hay they were feeding was notcontaminated with ragwort.

For more details see:

Biomarkers for ragwort poisoning inhorses: identification of protein targetsRE Moore, D Knottenbelt JB MatthewsRJ Beynon and PD WhitfieldBMC Veterinary Research 2008, 4:30(doi:10.1186/1746-6148-4-30)

Thoroughbred Racing and Breeding SeminarCheltenham Racecourse Thursday 13th November 2008

REGISTER NOW at www.thoroughbred-seminar.com2008Cheltenham

Equine Science Update12

Equine Science Updateis published byMark AndrewsCream Cottage, Low Church RoadMiddle Rasen, LN8 3TY UK

Tel/Fax: +44 (0) 1673-843187

Website: www.equinescienceupdate.co.uk

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All articles are written by Mark Andrews unless stated otherwise. Every effort is taken to ensure the accuracy of these reports, which are forinformation only. Veterinary Surgeons are advised to refer to the original paper if they wish to take action based on the information.

All material copyright Equine Science Update 2008

In this issue:

An increase in body temperature maybe the first sign of infectious disease. Soa quick and easy way of measuring thebody temperature could provide earlywarning of a disease outbreak.

Normally, the horse’s temperature istaken with a rectal thermometer. Thistechnique does have its limitations. Itcan be a hazardous procedure,particularly when young animals areconcerned. It is time-consuming. Andthere is the risk of transfer of bacteriaeither on the thermometer or on theoperator’s hand.

Microchips are becoming more widelyused for identification purposes. Inaddition to identifying an animal with aunique number, some microchipscontain a temperature sensor. Once thechip has been implanted in the horse(usually midway between the withersand the poll) it provides a simple way tocheck the temperature.

Chips have the advantage of beingquick to read, but does the readingaccurately reflect the rectal temperature?Do changes in environmentaltemperature affect the accuracy?Researchers in Colorado have beeninvestigating.

Tatiana Robinson and her colleaguesstudied the performance of temperaturesensitive microchips in two groups ofWelsh pony foals and a group of two-year-old Quarter horses. The ambienttemperature ranged from -16°C to 35°Cduring the study.

They compared the readings fromthermal-sensing microchips withmeasurements of rectal temperaturetaken with digital thermometers.

The thermal chips gave a wider rangeof temperatures than did the rectalthermometer.

The ponies had been exposed to a virusinfection and so some developed a fever(rectal temperature >38.9°C / 102°F)during the study. How useful were themicrochips at detecting ponies withraised temperatures?

The researchers found that theenvironmental temperature had a stronginfluence on the accuracy of the thermalmicrochip readings. When the ambienttemperature was less than 15.6°C, thesensor detected only half of the febrileponies.

On days when the ambient temperaturewas above 15.6°C, the sensor correctlyidentified 87% of febrile horses andcorrectly recognised 94% of the poniesthat did not have a raised temperature.

The researchers suggest that thethermal sensor could have a place forscreening horses for fever - providedthat the environmental temperature istaken into account when interpreting thereadings.

For more details see:

Comparison of temperature readings from apercutaneous thermal sensing microchip withtemperature readings from a digital rectalthermometer in equids.Tatiana R Robinson, Stephen B Hussey, Ash-ley E Hill, Carl C Heckendorf, Joe B Strick-lin, Josie L Traub-Dargatz.JAVMA (2008) 233, 613 - 617.

Measuring stridecharacteristics...........................1

Technological training..............2

Horse wormer study - helpneeded........................................3

Do tapeworms cause colic?.....4

Blood test for small redworms.....................................................4

How accurate are worm tests? 5

Preventing foal pneumonia......6

Effect of light on loading..........7

How important is eye contact.. 8

Dozing sign of satisfaction......9

Progress towards a blood testfor ragwort...............................10

Thoroughbred Racing andBreeding Seminar...................11

Measuring temperature with achip...........................................12

Measuring temperature with a chip.

Photo courtesy Dr Traub-Dargatz.