Acceptability of smaller microchips

Although microchips are widely used for identifying horses throughout Europe, there is still some resistance to their use, with questions being raised about stress during implantation, inflammation at the site of implantation, and reliability of detection.

In response to this criticism, microchips that are even smaller have been developed. They may be less stressful to implant, but do they work as well? Recent work has looked at whether such chips are reliable and if their implantation causes signs of stress.

The study, carried out at the Brandenburg State Stud at Neustadt (Dosse), Germany, was  reported by Manuela Wulf and others in a recent edition of the Veterinary Record. Forty adult mares were implanted,  on the left side of the neck, with a reduced-size microchip (10.9×1.6 mm). (Conventional microchips are 11.4×2.2 mm). Three different scanners were used to detect the microchips  immediately, and on three further occasions up to 28 weeks after implantation.

The researchers found that scanners differed in their ability to read the microchips, although all scanners detected all chips on every occasion when scanned from the side of implantation. One scanner read all microchips successfully from both sides of the neck on four occasions up to 28 weeks after implantation.  Two other scanners detected all of the chips from the side of implantation, but were less successful reading from the “wrong” side of the neck.

Did the horses find the implantation procedure stressful? The researchers monitored heart rate, heart rate variability and saliva cortisol levels during the implantation process in twelve of the mares. They also recorded the same information while pressing at the implantation site with a cannula without penetrating the skin. So each mare acted as its own control. They found a slight increase in heart parameters in both chip implantation and controls, but no change in cortisol levels.

The report's authors conclude that reduced-size microchips are highly reliable for identification of horses. “Compared with conventional microchips, the reduction in size did not impair readability. Microchip implantation is no pronounced stressor for horses.”

For more details see:
Reduced-size microchips for identification of horses: response to implantation and readability during a six-month period.
Wulf M, Aurich C, von Lewinski M, Möstl E, Aurich JE.
Vet Rec. 2013 Nov 9;173(18):451.
 doi: 10.1136/vr.101824

Riding Arena Footing and Management Webcast

Ever wondered what's involved in providing a top quality arena surface, or wanted to know more about the materials to use?

Here's your opportunity. There's a free webcast on “Riding Arena Footing and Management” from MyHorseUniversity on November 26, 2013 at 7 PM ET.

Dr. Ann Swinker, Associate Professor in Equine Sciences, Penn State University and Horse Extension Specialist has been involved in the horse business for over 35 years. She will discuss the physical properties of the various footing materials that are available and the advantages and disadvantages. She will also consider the management of arena surfaces, the principles of maintenance and the signs that a surface needs to be changed or replaced.

You can register for the webcast now. Don't worry if you miss it; you can still catch it later, as it will be archived on the website and will continue to be available (free).

For more details go to ....

http://myhorseuniversity.com/resources/webcasts/ridingarenafooting

Benefit of targeted worming

Worming only those horses that need it can be cost effective, even taking into account the cost of performing faecal worm egg counts, according to research published in the Veterinary Record.

It is now widely acknowledged that a targeted approach to worm control is preferable to interval dosing regimes. Current recommendations are that only those horses carrying a moderate or high worm burden are treated; thus ensuring that worms are not exposed to anthelmintics needlessly.

Faecal worm egg counts (FECs) are used to determine which horses need (or don't need) treating. To many owners this may seem an unnecessary expense. However, recent work has shown that using FECs in this way helps reduce the overall cost of worming.

Hannah Lester, with colleagues at the Moredun Research Institute, and the Universities of Bristol, Liverpool and Edinburgh, monitored FECs at 3 monthly intervals over a nine month period. In all, 368 horses from 16 separate yards were involved in the study.

Horses with FECs greater than 200epg were treated, with pyrantel (in March and June) and ivermectin (in September). All horses received moxidectin/praziquantel in December.

The researchers compared the cost with that of a standard interval regime of two treatments with moxidectin and two of moxidectin and praziquantel - which is what had been common practice in the study population.

They  estimated the cost of the two approaches by using average prices for anthelmintic products and faecal egg counts that they obtained off the internet. Even allowing for the cost of faecal egg count reduction tests  (ie repeating the FEC after each treatment to check the anthelmintic had been effective)  they found that, over the year, there was an average saving per yard of £294.44.

They conclude: “these findings support the notion that targeting anthelmintic treatments at those individuals with strongyle FEC of 200epg or greater facilitates a reduction in selection pressure for anthelmintic resistance. Moreover, the results show that such a strategy has a high chance of reducing the financial cost compared with that associated with more traditional interval treatment regimens, and horse owners should, therefore, be discouraged from the view that it is cheaper to treat all horses prophylactically over time.”

Read more: equinescienceupdate.com

Emergency ventilation system developed

Respiratory or cardiovascular arrest in outdoor animals poses a huge challenge to veterinarians. Ventilation equipment is generally hard to operate and requires electricity and compressed air, and is not easily transportable. 

Anaesthesiologists at the University of Veterinary Medicine, Vienna (Vetmeduni Vienna) have developed an inexpensive device that can be used to ventilate large animals. They report that it is easy to transport and can save animal lives in emergencies.

In work recently published in  Equine Veterinary Education, the scientists confirm that their emergency ventilator is effective in horses. 

Yves Moens is Head of the Vetmeduni’s Clinical Unit of Anaesthesiology and Perioperative Intensive Care Medicine. He and his colleagues have long been concerned by the number of horses that die avoidable deaths because of the lack of a suitable ventilation device. The device they designed is similar to the bellows used to inflate air mattresses but has been adapted by the addition of a manually operated expiratory valve.

Although it can only provide 2.5 litres of air, the researchers believed that it would provide sufficient ventilation if the bellows were activated several times in quick succession. They tested this idea on five anaesthetised Haflinger horses during castration surgery and showed that gradual ventilation with the 2.5 litre pump was sufficient to keep the animals alive.

 “It improves the safety of large animals in the field, both during routine anaesthesia and in emergencies. It will also help veterinarians to provide emergency first aid in these circumstances and respect the guidelines for good practice", says Moens. “The respiratory pump is inexpensive and easy to use and will help veterinarians treat their patients in the field.”

Read more : equinescienceupdate.com

How accurate is thermography of horses’ legs?

Infrared thermography is increasingly being applied to investigate the cause of lameness in horses.  The equipment is easy to handle and the method is fast and safe, both for the animal and for the vet.  But is it accurate? 

Recent work by Simone Westermann at the University of Veterinary Medicine, Vienna shows that the technique is surprisingly tolerant of variation in the position of the equipment, i.e. how far from the horse and at what angle to the animal the infrared camera is held. 

In fact, the results were almost completely unaffected by 20° changes in camera angle and increases of up to 50 cm in the distance of the camera from the animal.  At a distance of 1m from the horse a 20° change in camera angle corresponds to about 35 cm.  This represents the effective horizontal tolerance in positioning of the camera.  As Westermann says, “vets should have little difficulty in remaining within this limit, so the method is applicable in practice”. 

Surprisingly, the results showed that horses’ left and right forelimbs show minor differences in temperature and Westermann cautions that “it might be important to take these into account before reaching a final diagnosis.”

The technique is thus reliable and robust, at least in terms of variation in where the camera is located. 

However, it turned out to be extremely sensitive to even very gentle drafts.  A wind speed of less than 1 m/s causes a drop in measured temperature of about 0.6°C, while winds of 1.3-2.6 m/s cause a drop of 1.5°C and winds of 3-4 m/s cause a drop of 2.1°C.  The discrepancies are more than sufficient to lead to a wrong diagnosis, although even the highest wind speed tested is hardly perceptible:  it would barely cause leaves on trees to move.

Westermann is keen to note the relevance of her work for vets who work on horses.  As she says, “It turns out that it is not too important to be sure that the camera is in exactly the correct position before taking measurements.  But it is essential to perform thermography on horses in a room that is completely free of draughts.  If you don’t, your diagnosis will be completely unreliable.”

More information : equinescienceupdate.com

Antibacterial action of honey

Wounds to the lower limbs of horses can prove challenging to manage.  Recently there has been a growing interest in the use of honey in such cases.

Not all honey is the same. Its antibacterial quality depends on the type of honey and the conditions under which it was harvested and processed. Most honey contains hydrogen peroxide, which has antibacterial properties. Some types of honey contain other active components. For example, manuka honey is believed to have antibacterial properties due to high concentrations of methylglyoxal, a compound usually found in only low quantities in other types of honey.

Manuka honey, produced by bees foraging on manuka plants (Leptospermum scoparium), native to Australia and New Zealand, has been the subject of considerable research. Honey from other sources is often used in practice, but there has been little research into how effective it is.

Researchers at the University of Glasgow have been examining various different types of shop-bought honey to determine if they were free from bacterial contamination and suitable for use on equine wounds. They also investigated the effect of various examples of uncontaminated honey on the growth of equine pathogens, and  found that, in laboratory tests, certain varieties of honey are able to inhibit bacterial growth even at very low concentrations.

They found that many commercial sources of honey were contaminated with bacteria. The most commonly identified contaminating organism was Bacillus spp. However, potentially pathogenic organisms  (Proteus and Enterobacteraceae) were identifed in two honey samples.

Uncontaminated honey samples were subjected to further investigation to assess their antibacterial properties. Eight of the eleven samples tested were effective against all 10 bacterial isolates at concentrations from 4 to 16%. Overall, medical grade Manuka honey and a locally produced heather honey performed best.

The researchers conclude that many honeys have antimicrobial properties, and may be effective in the treatment of wound infections. They note that the concentrations at which honey samples inhibited microbial growth were much lower than is likely to occur at the surface of an infected wound treated with honey.

However, they advise that “the use of shop-bought honey on wounds should be avoided, as contamination with potentially pathogenic microbes appears to be common. Honey sourced within the UK is as, and in some cases more, effective than medical grade honey sourced in New Zealand.”




Read more at equinescienceupdate.com/articles/aah.html

New laminitis research findings

Laminitis continues to be a significant welfare problem of horses and ponies, causing widespread suffering. Investigations into the underlying causes and disease processes involved in the condition are ongoing.

The benefits of  feeding a balanced diet alongside appropriate forage, grazing restriction and regular low intensity exercise whenever clinically possible in the management of laminitis prone horses and ponies have been highlighted by new research.

Four separate studies have shed new light on the possible role of grass fructan in the development of laminitis; the influence of water temperature when soaking hay to reduce the water-soluble carbohydrate content; a possible link between recurrent laminitis and reduced anti-inflammatory capacity, and the potential anti-inflammatory benefits of exercise.

Read more at equinescienceupdate.com

Controlling forage intake with hay nets

Horses have evolved to spend much of the day grazing. However, modern systems of horse management often restrict the time available. This may contribute to problems such as gastric ulceration and can result in behavioural problems.

Sometimes it is desirable to reduce the intake of roughage – either to make the horse's ration last longer, or to limit its overall intake.

Recent research from the University of Minnesota shows that using hay nets with smaller holes is effective for limiting the rate of roughage ingestion in horses.

Eight horse were involved in the study. They were were housed in individual box stalls, and fed hay off the floor (control treatment) or from hay nets with one of three different sized holes. The mesh size ranged from 15.2cm (large), to 4.4cm (medium) and 3.2cm (small).

During the trial period, hay was available for two four-hour periods each day.

Horses were allowed to become accustomed to each type of net for 2 days, before intake was recorded over three days. They then had two days of a wash out period during which they were as a group in an outdoor paddock.

The researchers found a significant difference in the rate of consumption between all treatment groups. Horses fed hay off the floor (control) consumed hay at the rate of 1.49kg/hr. Consumption of hay from hay nets was 1.33kg/hr, 1.11kg/hr, 0.88kg/hr for large, medium and small sized holes respectively.

They found no difference between the large mesh net and control for the amount of hay consumed (both 95%% of hay offered); but medium and small hay nets restricted hay intake to 89% and 72% respectively.

They conclude that their results demonstrate that the medium and small sized nets were effective in decreasing both rate and amount of forage consumed by adult horses.





More information at equinescienceupdate.com

Geldings behaving badly

Some horses display stallion-like behaviour despite appearing to have been castrated. Before embarking on exploratory abdominal surgery, how do you distinguish between those with a retained testis (cryptorchid or “rig”) and those that just behave badly?

One technique is to assess resting serum testosterone concentrations to identify horses with functioning testicular tissue.

Recently published research suggests that testosterone levels vary through the year and that this should be borne in mind when interpreting the results. Apparently, spring is the best time to use a serum testosterone assay to confirm the presence of a suspected retained testicle.

Researchers at the Gluck Equine Center, University of Kentucky, and the University of California Davis (UCD), examined data from blood samples submitted from suspected cryptorchids to the clinical endocrinology laboratory at UCD.

Serum from 179  suspected cryptorchids with serum testosterone greater than 100pg/ml were included in the study. In the UCD laboratory, testosterone levels lower than 50pg/ml are interpreted as evidence of absence of testicular tissue, while levels >100pg/ml confirm the presence of testicular tissue.

The research team found that serum testosterone concentration varied with season, being higher in spring than at other times of the year and lower in fall compared with summer and winter. Concentrations of testosterone reached a peak in May and were lowest in November.

They also noticed a significant association between age and testosterone concentration – with testosterone levels  being lower in cryptorchids less than two years old. Testosterone levels also declined  in horses older than nine years old.

They advise that borderline low testosterone concentrations found late in the year might still be positive – so a further test should be performed the following spring if the animal continues to display stallion-like behaviour.

Horsecare smartphone app released

US veterinarian Doug Thal has developed a new smartphone app to help horse owners with equine health matters.

The aim of the app is not to replace the owner's veterinarian, but rather to improve the quality of communication between horse owner and vet, for the benefit of the horse, he says.

Dr. Thal believes that horses receive the best care from well-educated owners that have a strong relationship with their veterinarian. “In fact, good communication with your veterinarian at the onset of equine healthcare problems will likely give you more options, cost you less in the long run, and enable you to do the best by your horse“.

Horse owners are increasingly turning to the internet for information about horse health, he says. Sometimes they do so instead of calling the veterinarian. Too often this approach results in inappropriate or delayed treatment, and may eventually cost more.

Dr Thal, an equine veterinarian for 20 years, states that the Horse Side Vet Guide™ (HSVG) provides easy access to essential equine healthcare information, powered by a constantly growing knowledge base. “The idea that a horse owner could make an observation and immediately access credible information about that observation- literally “horse side” – is the driving concept behind this product”.

All the text records in HSVG  are downloaded to the phone, and so are available at any time, even without access to the internet. Videos, providing short demonstrations of skills that might be needed in an emergency, as well as anatomy images and tables of normal values, are also stored in the quick reference section. However, in order to keep the size of the app reasonable, access to many other videos, media, and outside resources do require an internet connection.

Horse Side Vet Guide is currently available for iPhone and costs $4.99.  An Android version is being developed.

Further details are available from: http://horsesidevetguide.com/

Australian search for anthelmintic plants

Scientists in Western Australia have been investigating the anthelmintic effect of various plant extracts. In a laboratory investigation, they screened extracts of 37 plants to see if they inhibited the development of cyathostome eggs. The results have been published in the journal Veterinary Parasitology.

Extracts from seven species completely inhibited larval development. A further ten species  resulted in 90% inhibition compared with controls.

The research team then took the seven most effective plants extracts and tested how their inhibitory effects were affected by diluting them. The most effective plants,  Alectryon oleifolius and Duboisia hopwoodii, had IC50 (concentration that resulted in a 50% inhibition of development) of 47.2μg/ml and 30.9 μg/ml respectively. In comparison, ivermectin had an IC50 of 0.0000817μg/ml - considerably more effective.

Further tests showed that the effective constituents of many of the plant extracts were likely to be tannins. Tannins may limit palatability, so plants whose anthelmintic  properties rely on them may not be ideal candidates.

However, the researchers identified two plants, Acacia melanoxylon and Duboisia hopwoodii, with anthelmintic properties that were not reliant on tannins.

A further consideration was that the plants may contain other constituents with possible adverse effects.  For example,  D hopwoodii, the most effective plant tested in this study, contains alkaloids such as nicotine and nornicotine, which are toxic for animals.

The search for plants with anthelmintic properties for use in horses is still in the early stages. This study looked at the effect on larval stages, while any anthelmintic would have to be effective against adult worms. Further work also needs doing to identify the active    constituents of the plant that are responsible for the anthelmintic effect.

Eventually, it may be possible to isolate and concentrate the active compound. The researchers calculated that a daily intake of 120g of the anthelmintic plants would expose parasitic worms in the horse's colon to concentrations of 1400 μg/ml – the concentration used in the initial screening test. So it would be feasible exert control over the helminth population by grazing pasture containing the plant or including it in the diet as a feed additive.

They conclude: this study “suggests that Australian plants may be useful in forming part of an integrated parasite management program for horses, but more studies are needed before developing appropriate applications.”

www.equinescienceupdate.com

Road safety: does bright clothing help?

Wearing lights when out riding on roads could be safer than wearing reflective or fluorescent clothing according to research presented at the International Society of Equitation Science annual conference, July 2013.

Rose Scofield, from Duchy College, Cornwall, UK conducted a questionnaire-based study to investigate the value of bright reflective clothing in reducing the risk of ”near misses” between horses and vehicles.

She distributed questionaires through equine websites and forums, receiving 426 replies. Participants answered questions regarding the fluorescent or reflective equipment they and their horses were wearing, and whether they had been involved in near miss incidents.

Scofield grouped the responses according to whether the respondents had experienced a “near miss” with traffic or not. Then she examined whether or not they had been wearing reflective and /or fluorescent clothing.

Most riders who responded to the questionnaire did use some reflective equipment or clothing when riding on the road.

However, when she analysed the data, what she found was perhaps surprising. Reflective clothing, worn either by the rider or the horse, appeared to have no significant effect on the likelihood of a “near miss”.

60% of riders reported a near miss. But the proportion wearing reflective clothing on either the horse or rider was similar to that of those who did not experience a near miss.

However, significantly fewer near misses were reported by riders wearing lights.Of all the riders, 8.2% wore lights and did not experience a near miss, whereas 3.6% had a near miss despite wearing lights.

“This suggests that wearing lights should possibly be recommended when riding on the roads to enhance the safety of both rider and horse and contribute to the welfare of the leisure horse in particular.” 

“The use of lights by a rider and horse combination may prove a sound contribution to the welfare of the leisure horse in avoiding possible road accidents.”

For more details see:
Road safety: is there a relationship between ‘near misses’ and the use of rider and horse reflective/fluorescent equipment?
Rose M. Scofield, Hannah Savin, and Hayley Randle,
Proceedings of the International Society of Equitation Science (2013) p30

Does whip use improve show jumping performance?

Researchers in the UK have turned their attention to the use of the whip in show jumping, to see whether it is associated with improved performance.

Catherine Watkins of Hartsbury College in Gloucester presented the results of the study at the 2013 International Society for Equitation Science (ISES) conference.

Whips are carried and used in competition by show jumpers at both the non-elite and elite levels. The study  showed that non-elite show jumping riders were more likely than elite riders to carry a whip. It also showed that increased use of the whip did not increase the chance of finishing with a clear show jumping round. In fact, when the whip was used, the horse was less likely to complete a clear round.

The researchers observed 229 non-elite and 229 elite show jumpers at affiliated UK show jumping competitions.

Non-elite riders were found more likely (69%) to carry a whip than elite riders (62%). Faults were 1.3 times more likely to occur for those riders who carried a whip. The likelihood of achieving a clear round decreased for riders who used the whip, with riders who carried but did not use a whip faring better. Elite riders who carried the whip but did not use it fared the best.

In addition to calculating the likelihood of achieving faults or clear rounds, the researchers compared active use of the whip with current British Show Jumping rules, which state that: misuse or excessive use will not be tolerated; the whip should not be used more than three times after entering the arena; the whip cannot be used prior to commencement of the course; and the whip is only used if the rider removes a hand from the reins.

In spite of these rules, Ms Watkins and her research partner observed seeing “a fair amount of misuse or excessive use of the whip in the arena” “The study found a total of 38 cases where the whip was used either as a punishment tool, or was not presented at the fence.” Of all the show jumping riders observed, none was reprimanded for misuse of the whip or rule infraction.

Of the 458 rounds observed, “Overall 65.5% of riders carried a whip…and 20.7% of those who carried a whip used a whip. Non-elite riders were more than twice as likely to use the whip.”
The researchers speculated that knowledge and experience level reduced the likelihood of the whip being used.  An alternative explanation is that elite riders are on higher quality, more athletic horses that simply don’t have as much “need” for the whip.

This information may be of value to both show jumping organizations reviewing position statements on whip use and equestrians competing in shows. “Those who used the whip were statistically less likely to achieve a clear round…elite riders were statistically more likely to achieve faults if the whip was used.” states Watkins.

With an increase in public awareness of welfare in equestrian sport, discussion of the rules governing whip use is gaining momentum. As evidence is emerging from other equestrian disciplines there is clearly a need for continuing review of whip use. The researchers hope that their study will help stimulate the debate.

For more details see:
Evaluation of whip use and prevalence in elite and non-elite show jumpers.
Catherine Watkins and Darcy Murphy.
Proceedings International Society for Equitation Science (2013) p54

700,000 year old horse DNA sequenced

Researchers have constructed the DNA from a 700,000 year old horse fossil from the far north west of Canada, which has challenged the accepted version of equine evolution.

Indeed, the widely accepted understanding of the horse's evolution is of a gradual increase in size from small forest-dwelling animals to the larger animals of today.

The fossil, found in the Klondike area of Yukon by  University of Alberta researcher Duane Froese, raised questions about this version of events. Not only was the  fossil considerably older than those commonly found in ice age deposits in the Yukon, Alaska and Siberia, it was also at least as large as many modern horses.

The layer of permafrost in which the fossil was found has been dated  by the volcanic ashes it contained as originating about 700,000 years ago. This puts it among the oldest known ice in the northern hemisphere.

An international research team, led by Ludovic Orlando, and colleagues at the University of Copenhagen, Denmark, managed to extract fragments of ancient DNA from the fossil. After several years work, they succeeded in constructing  a draft genome of the horse. This is by far the earliest genome sequence yet recorded. “Our data represent the oldest full genome sequence determined so far by almost an order of magnitude” they say in the report of their work, which is published in the journal Nature.

It is unlikely that the research would have been successful had the DNA not remained frozen over the past 700,000 years.

Having reconstructed the complete genome of the horse, the team compared it with DNA from a horse dating from the Late Pleistocene (about 43,000 years ago), and from five contemporary domestic horse breeds, a Przewalski's horse and a donkey.

By looking at differences between the DNA of the various horses, they could estimate the rate at which mutations occurred in the genetic code over time.

Analysis of differences between these genomes indicated the last common ancestor of all modern equids ( horses, zebras and donkeys ) would have lived about 4.0- 4.5 million years ago. This is about twice as far back than previously thought.

The results also indicated that Przewalski’s horse― an endangered subspecies native to the Mongolian steppes ― diverged from the lineage that gave rise to modern domesticated horses about 50,000 years ago.


More information at: equinescienceupdate.com

Genetics and tendon injury

Superficial digital flexor (SDF) tendon injury is a common cause of wastage in National Hunt Thoroughbred (TB) horses – leading to training and racing days lost and early retirement.

Recent research, funded by the Horserace Betting Levy Board, explored whether genetic susceptibility is a potential risk factor for SDF tendon damage in the TB racehorse.

The work, by Lucinda Tully and colleagues, compared the genotype of horses with and without SDF tendinitis in a case-control study.

Tully looked specifically at single nucleotide polymorphisms (SNPs) in seven genes that are involved in tendon structure, function, and remodelling or are known to be involved in Achilles tendinopathy (an equivalent condition in humans).

Genetic material for the study was derived from mane hair, or peripheral blood cells, collected from 270 horses with a history of SDFT strain, and 270 unaffected control samples, chosen at random from among the other horses on yards with affected cases.

The study's findings suggest that sequence variants in TNC and COL5A1 genes are associated with SDF tendinopathy in TB racehorses.

A SNP in COL5A1 significantly increased the odds of having SDF tendinitis. Racehorses having two copies of the COL5A1 COL5A1_01 variant allele were nearly 3 times more likely to have SDF tendinopathy than those homozygous for the wild-type allele.

Conversely , a SNP in the TNC gene was associated with significantly lower odds of SDFT injury. Racehorses heterozygous for the TNC BIEC2-696469 polymorphism were less likely to have SDF tendinopathy than those with two copies of the wild-type allele.

The research team conclude that variants in the TNC and COL5A1 genes are associated with SDF tendinopathy in a population of UK trained NH TB racehorses.

They suggest that further studies in a larger group of horses are needed to determine the significance of these findings at the population level.

In the future it may be possible to use genetic markers to identify horses at risk of SDF tendinopathy.

Read more: www.equinescienceupdate.com

Fishing for chips

Not only is chipping far more reliable for marking horses than traditional methods of branding, it also causes far less injury to the animals, according to research led by Christine Aurich at the University of Veterinary Medicine, Vienna.

With very few exceptions, it is now mandatory within the European Union to mark horses by means of transponders. Nevertheless, some sport-horse registries oppose the use of microchips because they believe that the rate of identification failure is unacceptably high.

Thus far, no systematic examinations to see whether chips are easy to decode, have been conducted. So Manuela Wulf in the group of Christine Aurich at the Vetmeduni Vienna has examined the readability of microchips in more than 400 horses. She tested each of the chips with three different scanners. The scanners differed in diameter and field strength. Both sides of the animals’ necks were tested.

The “best” scanner (equipped with a digital signal processing function that filters interfering signals) detected and read all chips correctly when it was placed on the side of the neck where the chip was implanted, and located nearly 90% of the chips even when it was on the other side of the neck. The other two scanners performed considerably less well, producing correct reads in around 90% of the cases when on the same side of the neck. On the opposite side of the neck, however, the success rate fell to between 20-25%.

It never took more than 25s to detect the microchip , and with the most effective scanner it took a maximum of 5 seconds. So the most effective scanner not only detected all the microchips , it did so in the shortest time.

As Wulf puts it, “It is important that the scanners find and read the chips correctly in every case. We can only recommend the top-of-the-range scanner, which should ideally be placed on the side of the horse’s neck where the chip was implanted.” However, Aurich adds, “Even the lowest quality scanner we tested, performed much better than traditional branding methods of horse identification.”

The major objection to the use of branding relates to the pain and long-term damage it inflicts on the animals. Wulf and her colleagues thus investigated whether the use of microchip markers was any better. She looked closely at the site of chip implantation in 16 horses of nine different breeds and of various ages that had been submitted to the Vetmeduni for post mortem examinations. In the vast majority of cases, the chips seemed to have caused absolutely no ill effects. Two animals that were moderately affected had probably only been chipped recently and the wound had not yet had time to heal.

Aurich sums up the findings, “Not only is chipping a far more reliable method for marking horses than traditional methods of branding, we also found that it causes far less injury to the animals.”

More information: equinescienceupdate.com

Does the human voice calm horses?

In addition to being warned to move slowly around horses, many new riders are also instructed to speak in a soothing tone, in the belief that it can make the animal calm. A recent study presented at the 2013 conference of the International Society for Equitation Science investigated whether such advice actually had a beneficial impact on the horse.

According to Katrina Merkies of the University of Guelph, “Anecdotally, we know that horses respond better to calm and soothing tones, so our hypothesis is that speaking in a calm and pleasant voice will inspire calm behaviour in a horse.”

Merkies and other researchers from both the University of Guelph, Ontario, Canada and Agrocampus Rennes, Rennes, France set out to discover whether emotional tone and pitch of voice did have any effect on horses. For the study, eight draft horses were individually assessed in a 10 m round pen. Each horse was released into the pen, and baseline behaviour and heart rate (HR) readings were taken over a five minute period. Behaviours scored included: gait; head height position; ear and body position relative to the human.

After establishing baselines, a familiar human approached the pen, and one of four recorded voices was played for a 10 second duration: PL – pleasant voice low tone; PH – pleasant voice high tone; SL – stern voice low tone; SH – stern voice high tone.

Researchers found that the horses maintained the lowest head position when no human or sound was present, but all elevated their heads in the presence of a human or sound. The playing of a pleasant tone resulted in the horses positioning their bodies toward the human. While there was no treatment effect on ear position, the horses did orientate their ears more toward the sound if the human was present.

Horse HR did not increase solely in the presence of the human, but it did increase coupled with sound, with SL in particular resulting in the greatest effect. Results would indicate that fewer signs of behavioural distress are observed when a human speaks to the horse in a pleasant, low tone rather than a stern tone.

“We’ve shown that horses do in fact display different physiological and behavioural responses to different tones and voice. So horses are able to discriminate between different tones or qualities of voice.”

Research often creates more questions than it answers, and based on the results obtained, additional research may be required: “However, it’s not clear if the horse is interpreting or responding to the tone of voice alone, or if it’s looked at in combination - both tone of voice and the human’s body language. Which is the more salient clue to the horse? That certainly warrants further study.”

Improving management of wild horses and burros

How to manage the feral horses and burros of the western United States has been the subject of heated debate for some time.

A recent scientific review found that the current practice of removing free-ranging horses is counter-productive. The review concluded that the current approach promotes a high population growth rate, and that maintaining horses in long-term holding facilities is both economically unsustainable and contrary to public expectations.

Most free-ranging horse populations are growing at 15 percent to 20 percent a year, meaning these populations could double in four years and triple in six years.

“With no intervention by BLM (the U.S. Bureau of Land Management), the horse population will increase to the point of self-limitation, where both degradation of the land and high rates of horse mortality will occur due to inadequate forage and water. In addition, periodic droughts, many of them severe, in the western public lands cause immediate and often unpredicted impacts.”

The report noted that there is little, if any, public support for allowing such harm to come to either the horse population or the land itself. However, the current removal strategy used by BLM actually perpetuates the overpopulation problem by maintaining the number of animals at levels below the carrying capacity of the land. Although this protects the rangeland and the horse population in the short term, it results in continually high population growth and exacerbates the long-term problem.

To manage horse populations without periodic removals, the committee concluded that widespread and consistent application of fertility control would be required.

Here's a video in which Committee chair Dr. Guy Palmer of Washington State University shares key findings about using science to improve the BLM wild horse and burro program.

The full report is available online.

http://www.nap.edu/catalog.php?record_id=13511

Hendra Virus Research Program

The impact of human behaviour on the spread of the Hendra virus is being studied to help develop control strategies.

HHALTER (Horse owners and Hendra Virus: A Longitudinal cohort study To Evaluate Risk) is a three-year project funded by the Commonwealth of Australia, the State of New South Wales, the State of Queensland and the Rural Industries Research and Development Corporation under the National Hendra Virus Research Program.

The project aims to look at how humans respond to the threat of Hendra virus, and what can be done by horse owners and others in regular contact with horses  to reduce the chance of transmission from flying foxes to horses and then to humans.

The researchers hope to attract more than 2500 people, horse owners and people in regular contact with horses, from all sectors of the equine industry throughout Australia.  It is not only residents of areas where Hendra virus cases have already occurred that are sought for the study. People living in parts of Australia  that have not seen cases of the disease are encouraged to take part as well.

Participants are asked to complete five surveys conducted at six-month intervals. The surveys investigate the factors influencing people’s awareness about the risks from Hendra virus and their use of prevention strategies.

Dr Kate Sawford,  Research Associate in Animal Health Biosecurity at the University of Sydney, said: “The combination of a high human death rate, no cure and no human vaccine means that Hendra virus is a frightening disease. An outbreak of Hendra virus on a property cannot only impact people’s health, but also be financially, professionally, emotionally and psychologically damaging.

The first survey with horse owners and horse care providers has now been completed. This focused on Hendra virus risk awareness, perceptions and knowledge, with large sections dedicated to practices employed on properties to limit the risk from the virus  and attitudes to vaccination.

Another four surveys with horse owners and horse care providers will be conducted over the next two years.

To participate in the research project or find out more information visit http://www.uws.edu.au/hhalter

A brief summary of some preliminary findings is available in the first HHALTER Project Research Newsletter.

Tick paralysis high death rate

Tick paralysis is more likely to be fatal in horses than in small animals according to recent research.

Findings presented at the Australian Veterinary Association conference showed that 26% of affected horses died and 35% of surviving horses developed one or more complications.

Tick paralysis,is caused by the Australian paralysis tick Ixodes holocyclus, and has been known to affect horses since the early days of Australian settlement.

Dr Mick Ruppin, one of the co-authors of the study explained: “The paralysis tick is found predominantly along the east coast of Australia, in high rainfall areas. Our study was a retrospective analysis of cases treated at our practice on the east coast of Queensland, over the last ten years, as well as cases treated at other practices along the east coast over the last five years. A total of 103 cases were analysed.

“The number of paralysis ticks required to paralyse a horse is unknown but our study included cases where large horses with only one to two ticks were paralysed and unable to stand. Horses of any age and size can be affected by tick paralysis” Dr Ruppin added.

“The mortality rate of 26% in horses is much higher than the mortality rate in small animals which is around five per cent.

Dr Ruppin said that higher mortality rates in horses could be due to a range of factors including horses being badly affected before vets are called; difficulties associated with nursing a recumbent horse; difficulties with owners needing to deliver the bulk of nursing care and lack of information to veterinarians treating the disease in horses.
 
“In our study, 26 % of the horses died and of the surviving horses, 35% developed one or more complications including pressure sores, corneal ulcers, pneumonia and sepsis.

“Given the difficulties associated with treating tick paralysis in horses, prevention is the best option for horse owners,” he said.

Read more at equinescienceupdate.com

Sycamore linked to Atypical Myopathy

 Toxic seeds of the sycamore (Acer pseudoplatanus) are the likely cause of Atypical Myopathy (AM)

Atypical Myopathy is a highly fatal muscle disease of horses in the UK and Northern Europe. In ten years, approximately twenty European countries have reported the disease. Incidences tend to occur repeatedly in the autumn and in the spring following large autumnal outbreaks. Horses that develop AM are usually kept in sparse pastures with an accumulation of dead leaves, dead wood and trees in or around the pasture and are often not fed any supplementary hay or feed.

A very similar disorder, Seasonal Pasture Myopathy (SPM), which occurs in Midwestern USA and Eastern Canada, is now known to be caused by a toxin (hypoglycin A), contained in seeds from the box elder tree.

The European research team, led by Dominic Votion, of the University of Liege, studied 17 horses from Belgium, Germany and The Netherlands, suffering from Atypical Myopathy. They found high concentrations of methylenecyclopropyl acetic acid (MCPA), a toxic metabolite of hypoglycin A, in the serum of all affected horses.

The pastures of 12 of the horses were visited by experienced botanists and Acer pseudoplatanus, the sycamore maple, was found to be present in every case. This was the only tree common to all visited pastures. Acer negundo, the box maple, was not present on any of the farms on which atypical myopathy occured.

Researchers believe hypoglycin A is the likely cause of both AM in Europe and SPM in North America. The sycamore and the box elder are known to produce seeds containing hypoglycin A and the pastures of the afflicted horses in Europe and the USA were surrounded by these trees.
in European horses, according a new study.

Read more at equinescienceupdate.com

More help needed for saddle slip study

Horse riders are being asked to help with an important research project looking into the interaction between horse, saddle and rider.

Researchers, led by Dr Sue Dyson, Head of Clinical Orthopaedics at the Centre for Equine Studies at the Animal Health Trust, are running a detailed study to find out how the horse, rider and saddle influence each other. In particular they want to understand better why some saddles persistently slip to one side in some horses.

Saddle slip in sports horses is a well-recognised problem that can occur for a variety of reasons, including asymmetry in the shape of the horse’s back, riders sitting crookedly and ill-fitting saddles.

Participants in the study simply need to complete an anonymous online questionnaire. In doing so the researchers say that they will be helping to protect and improve the future health, welfare and longevity of the ridden horse.

Preliminary invevstigations have looked at just over 700 riders, but for a more accurate picture the research team would like to include more than 1000 people.

“We are urging all riders, whatever their level or ability, to help by completing the questionnaire,” said Line Greve, a PhD student at the Centre for Equine Studies.

“Saddle slip is a problem seen in all sorts of horses and ponies and can contribute to back pain and thus impaired performance,” she explains. “Research suggests that 25% of British dressage horses have a history of back-related problems and subsequent reduced performance.”

The online questionnaire should take no more than 15 minutes to complete. The questions cover saddle types, use and maintenance as well as rider experience and training, and any previous equine lameness or back-related problems.

Participants will remain anonymous and the results will be presented at the Saddle Research Trust Conference in 2014.

To take part in the study, follow this link to the questionnaire
http://www.aht.org.uk/cms-display/premise_questionnaire.html.

Sperm from dead horses

The unexpected death of a prize stallion need not necessarily spell the end of his breeding career.  Obviously many breeding stallions will have had semen frozen and stored for future use. But what if that has not been done?

Or you may have a promising colt and be unable to decide between keeping him entire for breeding, or having him castrated. The answer may lie in cryopreservation of epididymal sperm.

It is now possible to salvage sperm from the tail of the epididymis – the long convoluted tube into which the sperm pass after being produced in the testis. As well as acting as a reservoir for the sperm, the epididymis provides an environment in which they can mature and become able to fertilise oocytes.

The procedure for harvesting and freezing the sperm is not widely available. So what can be done if the laboratory is a long way away? Will  delay adversely affect the viability of the sperm?

Research in the Department of Physiology at the University of Murcia in Spain suggests that spermatozoa stored in the epididymis for up to 96 hours at 4º C can be cryopreserved successfully and still retain the ability  to fertilise. 

In work published in the journal Animal Reproduction  Science, Luis Vieira and others  studied the viability of sperm stored  in the epididymis obtained from castrated horses.

Testes were transported to the laboratory in insulated  containers at ambient temperature within one hour of castration. At the laboratory, the epididymides were washed in physiological saline, wrapped in foil to prevent them drying out, and stored in a refrigerator at  4º C for up to 96 hours.

The scientists harvested the sperm by introducing a syringe and needle into the vas deferens and flushing out the epididymal contents. The sperm were mixed with extender before being frozen and stored in liquid nitrogen.

Measurements  of viability of sperm in the epididymal fluid were made at various stages in the procedure.

Viability was good (85%) if the sperm were harvested on the day of castration , and remained at more than 80% until 72 hours after castration. Sperm stored for 96 hours before harvesting were significantly less viable.

After dilution in the freezing media and storage at 4º C for 30 minutes, viability remained good for sperm harvested within 48 hours of castration.  Viability was lower in sperm collected 72 and 96 hours after castration.

On the other hand, time (up to 96 hrs) from castration to harvesting did not appear to affect the viability after freezing and thawing, which was almost 35%.

Other measures of sperm viability and tests of their ability to fertilise in vitro, were carried out, including chromatin condensation, ROS generation, protein tyrosine phosphorylation and heterologous fertilization rate. These showed that epididymal stallion sperm stored for up to 72h in the epididymis at 4°C followed by cryopreservation, maintained both viability and ability to fertilize in vitro.

Although these were laboratory tests of viability, epididymal sperm have been used successfully.

Read more at equinescienceupdate.com

When to stop Lyme disease treatment?

Don't expect Borrelia antibodies to disappear rapidly following treatment in horses naturally infected with Lyme disease.

Lyme disease (LD) is caused by systemic infection with the spirochaete Borrelia burgdorferi. The most common signs in affected animals are lameness, often affecting more than one limb, and reluctance to work. Diagnosis of the disease is complicated by the many other possible causes of lameness and the high incidence of sub-clinical infection in areas in which the infection occurs. Many clinically normal animals have antibodies to Borrelia burgdorferi in their blood.

How do you decide on the length of treatment course necessary in cases of Lyme disease in horses?
Changes in the antibody levels are often used to assess when treatment has been successful. In experimental infections, infected animals show marked reduction in antibody levels after antibiotic treatment.

Does the same apply to naturally infected cases? Research in New York State suggests that ELISA serology is less helpful in those cases for determining when treatment is complete.

The study saw Dr Thomas J Divers and colleagues at Cornell Veterinary School  collaborating with Dr Amy L Grice of the Rhinebeck Equine practice in New York State.

Thomas J Divers and colleagues at Cornell Veterinary School and Dr Amy L Grice of the Rhinebeck Equine practice compared Borrelia ELISA antibody concentrations in naturally exposed horses before and after antibiotic treatment for Lyme disease. The study included 68 horses treated with doxycycline or oxytetracycline and 183 horses that received no treatment.

They found that antibiotic treated horses had a decline in ELISA values in comparison to control horses. The scale of the decline in ELISA units following treatment was small compared to that previously reported in experimentally infected and treated ponies.

They conclude: “Persistently high ELISA titres following appropriate treatments for Lyme disease may not, without appropriate clinical signs, be a reason for more prolonged treatment.”

 Read more at equinescienceupdate.com

Healthy horses needed for research study in Saskatchewan

Researchers at the Western College of  Veterinary Medicine (WCVM) in Saskatoon are looking to enrol between 40 and 50 healthy horses for a respiratory study this summer.

The study, led by Dr Julia Montgomery and Dr Katharina Lohmann, aims to determine reliable reference ranges for two common tests used to investigate respiratory disease in horses.

In the WCVM newsletter, Christina Weese writes that that questions about the two tests initially arose when a graduate student was studying lung inflammation markers in normal horses.

“We started looking at what the expected ranges for two common tests – tracheal wash and bronchoalveolar lavage (BAL) – were supposed to be,” explains Dr. Montgomery, an assistant professor in the WCVM’s Department of Large Animal Clinical Sciences.

“In the course of the study, we came across several horses that looked clinically healthy, but their tracheal wash and BAL levels were - according to the current definition - not normal.”

To be eligible for the study, horses should have no history of chronic airway disease, no history of respiratory disease within the last six months and no clinical symptoms at the time of the study. Also, to ensure collected samples remain viable, horses must be within two to three hours’ drive from the WCVM.

An initial examination will identify whether the animal is suitable for the study. The clinicians will perform a clinical examination, including listening to the heart and lungs and checking the temperature. They will also carry out a rebreathing test. This involves placing a bag over the horse's nose, making him breathe deeply, which may make any abnormalities in the lungs easier to detect.

If any signs of abnormality are discovered, the horse will not be suitable for the study and no further tests will be carried out.

If the respiratory system appears normal then further tests to sample fluids from the trachea (“tracheal wash”) and lungs (“brocho-alveolar lavage”) will be performed under sedation.

After samples are collected, team members will examine the blood work for any evidence of inflammation. Dr. Hilary Burgess, a veterinary clinical pathologist at the WCVM, is collaborating with Montgomery and Lohmann to do a cytological analysis of the tracheal wash and BAL samples. The samples will also be sent to the bacteriology lab at Prairie Diagnostic Services (Saskatchewan’s provincial veterinary laboratory) to determine what types of bacteria may be present.

Lohmann and Montgomery say their results will provide invaluable baseline information for equine populations around the Saskatoon area. The study will also help them to identify the next steps for future investigations of equine airway diseases such as RAO.

All study procedures can be carried out at the owners premises, and are free of charge.

The study runs from May to August 2013. More details can be found at:
http://www.usask.ca/wcvm/vmc_clients/respiratory_study/

Measuring response to flexion tests

For many years, opinions on the value of flexion tests in assessing equine lameness have been divided. Now, new research has shown that a system based on a wireless, inertial sensor can be used to measure the horse’s response to a flexion test.

Horses were fitted with sensors on the head, pelvis and right forelimb. The sensors measured vertical pelvic movement asymmetry for both right and left hind limb strides and the average difference in maximum and minimum pelvic height between right and left hind limb strides.

The response to a hind limb flexion test was assessed by an experienced observer and compared with measurements taken with the horse trotting before and after flexion.

John Marshall, lecturer in equine surgery at the University of Glasgow, who led the study, concluded: “A positive response to flexion resulted in significant changes to objective measurements of pelvic symmetry, supporting the use of inertial sensor systems to objectively assess response to flexion tests.

Read more at equinescienceupdate.com

Tapeworms in working donkeys in Ethiopia

Tapeworms are a potential problem amongst working donkeys in Ethiopia research has revealed.

The work, carried out by Dr Mulugeta Getachew formed part of his PhD studies and was funded by the Donkey Sanctuary.

He conducted a serological survey of donkeys from four different geographical regions of Ethiopia. Blood samples were collected from 797 donkeys, that had been naturally exposed to tapeworm infection. None had never been treated for tapeworms.

The tapeworm ELISA test, developed for use in horses, was used to detect parasite-specific serum antibody, IgG(T), in the serum of donkeys. A pilot study had confirmed that the test was suitable for use with donkey sera.

Dr Getachew found substantial serological evidence that donkeys were potentially infected with the tapeworm Anoplocehala perfoliata.

Overall, most animals harboured few parasites and a few donkeys were infected with

large number of parasites. The results indicated that 26% and 8% of the donkeys were moderately and highly infected, respectively. The remainder had low infection intensity or were negative for A. perfoliata infection.

He found a marked difference between results from different regions of the country. Bereh, a mountainous region, had significantly more moderately (51.2%) or highly (23.5%) infected donkeys, than the other midland or lowland regions.

He explains that, in contrast to the other regions studied, Bereh is characterized by pastures that are low-lying and wet, with wide areas of permanent pasture specifically kept for animals and for haymaking.This is likely to result in favourable environmental conditions for the survival and development of both the oribatid mites that are the tapeworm's intermediate host and the tapeworm eggs.

He concludes: “The finding of high sero-prevalence of cestode (tapeworm) infection, which is consistent with the results of coprological and post-mortem findings clearly indicates that cestodosis is one of the major parasitic problems in the donkey population of Ethiopia.”

“These results indicate a risk of intestinal disorders, particularly, colic, associated with A. perfoliata infection in donkeys.”

Read more at www.equinescienceupdate.com

Effect of composting on Parascaris equorum eggs

The eggs of the large roundworm of horses, Parascaris equorum, are particularly resistant to extremes of climate and may survive for many years in stables and on pasture. Composting is becoming a popular method of dealing with waste from equine premises. How likely are P. equorum eggs to survive in composted manure?

A study carried out by researchers from the University of Kentucky Department of Animal and Food Sciences on a central Kentucky horse farm investigated the viability of P. equorum eggs in manure subjected to windrow composting.

For the purposes of this study, a single windrow approximately 42.3m in length, 2.7m in width, and 0.9m in height was built. It contained equine manure, soiled bedding and other waste material, which came from stables occupied by adult stallions and mares. Temperature and carbon dioxide levels within the row were monitored daily. The compost would be mechanically turned and aerated as necessary to maintain optimum conditions. Previous experience had shown that it took 10-12 weeks for the windrow to decompose completely.

Sentinel chambers were used to expose 3g samples of feces to the composting process. The faeces, collected from a weanling foal, had an average of 2216 P. equorum eggs per gram.

The chambers were made of mesh that kept the P. equorum eggs inside, whilst allowing liquids and bacteria to pass through.

 

Chambers were exposed to one of three treatments.

1. Constant exposure. These were placed within the centre of the windrow. Each day after the windrow had been turned, the chamber was placed back in the centre of the windrow.
2. Intermittent exposure. The chambers were placed in the centre of the windrow. On alternate days, after the windrow had been turned, the chamber was placed back in the centre, or placed on the outside of the windrow.
3. Control chambers were kept at 4°C.

Every two days, one chamber from each group was removed and incubated at room temperature for 21 days, at which stage the eggs were examined microscopically to assess if they were viable. (Viable eggs contained larvae.)

Chambers treated with constant exposure contained about 10% viable eggs on day 2 and 0% by day 8. Intermittent treatment resulted in 16% viable eggs on day 2 and 0% by day 6. In contrast , control chambers had average P. equorum egg viabilities of 79% throughout the 18 days of the study.

The researchers concluded that not only was the windrow composting system effective in eliminating viable P. equorum eggs, it did so rapidly. 

 For more details see: http://www.equinescienceupdate.com/articles/ecpee.html

Information sought on saddle slip

Can you spare a few minutes to complete a questionnaire to help research into saddle slip? Scientists at the Animal Health Trust are trying to understand more about the reasons for a saddle to slip persistently to one side in some horses.

To this end they have devised a questionnaire to examine the interactions between horses, saddles and riders.

Saddle slip is a problem seen in all sorts of horses and ponies and can contribute to back pain. It may also be a sign of hindlimb lameness.

A recent study by Line Greve and Sue Dyson at the Animal Health Trust Centre for Equine Studies in Newmarket, found that that saddle slip is not necessarily due to an ill-fitting saddle or asymmetric shape of the horse’s back.

Sue Dyson said: “Detection of saddle slip provides an opportunity for the owner, riders and trainers to detect low-grade and subclinical lameness, with important welfare consequences.”

Greve and Dyson are continuing their investigations, trying to understand more about the reasons for a saddle to slip persistently to one side in some horses. To this end they have devised a questionnaire to examine the interactions between horses, saddles and riders.

The questionnaire should only take a few minutes to complete, and will help reveal the frequency of occurrence of saddle slip and the risk factors involved.  Follow the link for more details...

http://www.aht.org.uk/cms-display/premise_questionnaire.html

Maggot wound therapy

Maggots might be the last thing you'd want to find in a horse's wound. But a recent study assessed the efficacy of maggot debridement therapy in a range of equine lesions and found it was beneficial in 93% of cases.

Over a four year period, Dr Olivier Lepage and colleagues treated forty-one cases (35 horses, 4 donkeys, 2 ponies ) in France and Mali.

The maggots used were sterile common green bottle fly maggots, which have been used in human medicine to clean long-standing, infected or necrotic wounds. Maggots digest fibrin and necrotic tissue, along with bacteria, and secrete proteolytic enzymes and antimicrobial agents into the wound.

Interestingly these are the same species of fly larvae that are the most common cause of fly strike in rabbits and sheep. In horses (and humans) it appears that healthy tissue is able to inactivate the proteolytic enzymes so that only diseased tissue is digested. In contrast, sheep and rabbits can not inactivate the enzymes.

Maggots were applied either directly onto the wound or retained within a polyester net containing small pieces of foam. They were kept in place with cohesive, but not occlusive, bandage – maggots need oxygen.

Between 300 and 900 maggots were used for each wound, depending on its size. They were left in place for three days. In 5 cases the response to the initial MDT was inadequate and so a second treatment was applied for a further 3-4 days.

Conditions treated included limb lacerations, deep seated foot infections and soft tissue abscesses and abdominal incision breakdown. Within just one week a favourable outcome was recorded in 38 of 41 cases. Wounds that did not respond well were those involving neoplasia or a bone sequestrum.

No more than 2 MDTs were needed in this series of cases, in contrast to other reports. The clinicians suggest that this was likely due to the light surgical debridement that was carried out in most cases in this series, before the maggots were applied.

Lepage and colleagues conclude that maggots can be recommended in horses, ponies and donkeys for debridement of wounds and for their potent antibacterial effects – including their use against difficult to control infections such as MRSA and other multibacterial resistant bacteria.

They advise against its use in cases where neoplasia is present. In this study, melanoma and squamous cell carcinoma continued to deteriorate after MDT.

 Read more: www.equinescienceupdate.com

Developmental joint disease in Norwegian Standardbreds

A research project carried out at the Norwegian School of Veterinary Science has revealed that 50.7% of Norwegian Standardbred yearlings suffer from loose bone fragments and lesions in their joints.

Developmental orthopaedic disease is well recognised in the horse, and can result in lameness or poor performance. It can appear in various forms such as: osteochondrosis (OC)/osteochondrosis dissecans (OCD), palmar/plantar osteochondral fragments (POF or “Birkeland fractures”), ununited palmar/plantar eminences (UPE) and dorsoproximal first phalanx fragments.

The aim of the study, led by Sigrid Lykkjen, was to assess the prevalence, development and interrelation of the various forms of developmental orthopaedic disease (DOD) affecting the tarsocrural, metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in Standardbred trotters.

The work formed the basis of her PhD thesis entitled “Genetic studies of developmental orthopaedic joint diseases in the Standardbred trotter”. The research was carried out as a collaborative project between the Horse Clinic and Department of Disease Genetics at The Norwegian School of Veterinary Science, the University of Ås and the University of Minnesota.

Tarsocrural and MCP/MTP joints of 464 Norwegian Standardbred yearlings, born in 2006 and 2007,were examined radiographically. Lykkjen assessed the prevalence of osteochondral lesions and also looked at the interrelation between affected sites.

She found osteochondral lesions in 50.7% of the horses. OC/OCD of the tarsocrural (hock) joint occurred in 19.3%. Of the lesions in the hock joint, OCD of the distal intermediate ridge of the tibia (DIT) was the most common. The prevalence of OC/OCD in MCP joints was 3.6%, whereas the prevalence of POF and UPE in MCP/MTP joints was 23.1% and 3.9%, respectively. 

 

It was common for horses to have similar lesions on the opposite leg. There was an association between OCD of the distal intermediate ridge and OCD of the lateral trochlea ridge, and between POF and UPE.

The high prevalence results for tarsocrural OC/OCD emphasise the need for breeders to take account of these diseases in planning their breeding programme.

^{Read more at: www.equinescienceupdate.com/articles/djdns.html}