Management affects large intestinal motility

A possible explanation for the increased risk of impaction colic in stabled horses has been revealed by a study that shows that they have lower large intestinal motility compared with horses at pasture.

The research team, led by Dr Sarah Freeman at the University of Nottingham School of Veterinary Medicine and Science, measured the motility of the large intestine at three regions of the large intestine, using transcutaneous ultrasound.

The study involved sixteen clinically normal horses, which were divided into two groups.

Group A: Horses were stabled continuously throughout the study.
Group B: Horses were initially at pasture 24hr/day. Over a 2 week period they were gradually changed to the same stabling/dietary management as group A.

The researchers assessed the motility of large intestine twice daily for two consecutive days. They recorded the number of contractions at each of three sites: the caecum, sternal flexure, and left ventral colon.

Overall large intestinal motility as assessed by transcutaneous ultrasound was lower in stabled horses. In particular, stabled horses showed significantly fewer contractions in the sternal flexure and left ventral colon.

 Read more at www.equinescienceupdate.com

Laminitis due to endocrine disorders

Hormonal disturbance (endocrinopathy) appears to be a common underlying cause of laminitis according to research from Finland.

The study, conducted at Helsinki University Equine Teaching Hospital, looked for signs of endocrinopathy in all cases of laminitis presented for examination. Almost 90% of horses with laminitis had endocrine abnormalities.

Hyperinsulinaemia, associated with obesity was the most common cause, accounting for two thirds of all cases of endocrinopathic laminitis.  Cushing’s disease (or Pituitary Pars Intermedia Dysfunction: PPID) was responsible for a third of the endocrine-associated laminitis cases.

Dr Ninja Karikoski and colleagues examined 36 horses and ponies with laminitis. Thirty-two of them (89%) had signs of endocrinopathy.

Eleven horses had signs of PPID - hirsutism (long curly coat) and increased basal ACTH concentration or typical response to a dexamethasone suppression test.

Twenty-one horses had raised basal levels of insulin in the blood without signs of hirsutism.  All but one of these hyperinsulinaemic horses were overweight. Twelve had a body condition score (BCS) of four, (on a scale from zero to five, where five is obese) and eight had BCS of five.

The researchers conclude that, in this study, most cases of laminitis were associated with an underlying hormonal disturbance.

They suggest that endocrine testing should be performed on all cases of laminitis unless there is a clear inflammatory or gastrointestinal cause.

 Read more at www.equinescienceupdate.com

Jet lag benefits racehorses

A new study has shown that not only do racehorses cope better with jet lag than humans do, but also their performance even appears to be enhanced by it.
  
They research showed that horses adapted very quickly to a shift in time zone. Importantly, this rapid adaptation was not accompanied by an increase in the level of stress, but by alterations in endocrine systems that favour an enhancement of the horse’s physical capacity during the process.
 
In fact, following experimental jetlag, horses experienced improved athletic performance, being able to run at full gallop for an additional 25 seconds before reaching fatigue.
 
This improved performance did not persist, however, and had returned to pre-shift values after 14 days in the new lighting conditions.

 Read more at www.equinescienceupdate.com

Comparing positive and negative reinforcement training methods.

A recent study in Denmark suggested positive reinforcement methods were preferable to negative reinforcement when training horses in potentially stressful situations.

They found that found that horses trained with positive reinforcement methods trained more quickly and showed less evidence of stress. 

What is the difference between positive and negative reinforcement? In Positive Reinforcement (PR), the desired behaviour is encouraged by giving a reward as a consequence of the behaviour.

A particular behaviour can also be encouraged by removing an unpleasant stimulus. This is known as Negative Reinforcement (NR). In this case, the reward is the stopping of a negative stimulus once the correct behavioural response is achieved.

Negative reinforcement differs from punishment, in which an adverse stimulus is given as a consequence of the behaviour. This results in the behaviour becoming weaker or stopping altogether.

Twelve horses took part in the study. All had previous bad experiences with trailer loading and their owners were now unable to load them.

Horses were randomly separated into two groups. The PR group received clicker training and were trained to follow a target (a yellow ball on a stick) into the trailer. For the NR method, an adverse stimulus was applied by pulling on the lead rope, or tapping the hindquarters with a whip. This adverse stimulus was stopped as soon as the horse obeyed.

Throughout the training sessions, the research team recorded heart rate, and noted signs of behaviour and discomfort.

Comparing the two methods, the researchers found that PR provided the fastest response to training. On average, the PR group spent less time on training sessions than did the NR group.

Read more at www.equinescienceupdate.com

Progress towards a vaccine against deadly foal pneumonia

 Rhodococcus equi bacteria can cause “rattles”, a potentially lethal disease in foals which is characterized by chronic broncho-pneumonia with abscesses in the lungs. Other forms of the disease occur including infection of the intestine and lymph nodes.

Affected animals show signs of fever, cough, rapid breathing, and nasal discharge. The disease tends to develop insidiously. Few signs may be apparent until the disease is quite advanced. The organism is often found in soil, particularly in dry dusty conditions.

Treatment usually requires an extended course of antibiotics and/or immune plasma. If the infection is diagnosed too late, antibiotics are often no longer sufficient to cure the disease, and death may occur within weeks.

Despite the severity of this disease, no vaccine against it is yet available. However, researchers in The Netherlands have now developed a promising candidate vaccine.

Read more at equinescienceupdate.com

Ancient wild horses help reveal past

An international team of researchers has used ancient DNA to produce compelling evidence that the lack of genetic diversity in modern stallions is the result of the domestication process.

Modern domestic horses show abundant genetic diversity within mitochondrial DNA, which  is inherited only from the female. In contrast there is practically no variation in the DNA sequence on the male-inherited Y-chromosome.

Several hypotheses have been proposed to explain this difference, but to be able to test them it is necessary to know about the degree of variation in the ancestral horse population. The only way to get this information is by studying ancient DNA.

The research team, which was led by Professor Michi Hofreiter from the University of York, UK, has carried out the first study on Y chromosomal DNA sequences from extinct ancient wild horses and found an abundance of diversity.

The results, which are published in Nature Communications, suggest the almost complete absence of genetic diversity in modern male horses is not based on properties intrinsic to wild horses, but on the domestication process itself.

Professor Hofreiter said: “Unlike modern female domestic horses where there is plenty of diversity, genetic diversity in male horses is practically zero.

“One hypothesis to explain this suggests modern horses have little Y chromosome diversity because the wild horses from which they were domesticated were also not diverse, due in part to the harem mating system in horses, implying skewed reproductive success of males. Our results reject this hypothesis as the Y chromosome diversity in ancient wild horses is high. Instead our results suggest that the lack of genetic diversity in modern horses is a direct consequence of the domestication process itself.”

Read more : http://www.equinescienceupdate.com/articles/awhhrp.html

Identifying the cause of Foal Immunodeficiency Syndrome

Researchers in the UK have now published details of their work which resulted in the development of a genetic test for Foal Immunodeficiency Syndrome (FIS, otherwise known as Fell Pony Syndrome).

By comparing the genetic material from affected foals, known carriers with no clinical signs, and normal animals, the research team were able to track down the mutation responsible to a particular portion of chromosome 26. Further studies showed that the genetic defect affected the sodium/myo-inositol cotransporter gene (SLC5A3).

In the report of their work published in PLoS Genetics, they explain: "This gene plays a crucial role in the regulatory response to osmotic stress that is essential in many tissues including lymphoid tissues and during early embryonic development. We propose that the amino acid substitution we identify here alters the function of SLC5A3, leading to erythropoiesis failure and compromise of the immune system. FIS is of significant biological interest as it is unique and is caused by a gene not previously associated with a mammalian disease. "

"Having identified the associated gene, we are now able to eradicate FIS from equine populations by informed selective breeding."

Read more at www.equinescienceupdate.com

Effect of blinkers

How do horses respond to partial loss of vision?

In a study at Texas A & M University, eight driving horses were assessed to see if they responded differently to stimuli when wearing blinkers or not. A racing hood with half cup blinkers was used to restrict the field of view behind the horse. A similar racing hood without blinkers was used as a control.

One experimenter administered one of four stimuli while standing about nine strides behind the horse:

• a length of steel chain was dropped onto an aluminium sheet
• a children's toy gun was fired
• an aluminium can containing coins was shaken
• an umbrella was rapidly opened

The horse's heart rate was recorded after each stimulus.

They found that wearing blinkers was significantly associated with an increase in heart rate when worn by horses experiencing a noise for the first time. On the other hand, blinkers were significantly associated with a decrease in heart rate when worn by horses exposed to a primarily visual stimulus (the umbrella opening).

"It would seem logical that wearing blinkers would be advantageous when a visual distraction is hidden by the blinkers. Because the horses cannot see the object, he has no reaction to this object which is potentially frightening" they comment.

However, sounds are different. "This paper shows that horses wearing blinkers react more when they are exposed to unexpected noises." They point out that this reaction is not necessarily seen by an observer - most of the horses in the study showed little visible reaction to the noise stimuli. There was, however, a dramatic increase in heart rate.

The researchers suggest that this model of restricted vision could be used to investigate how horses react to other visual deficits such as total blindness, or the changes that occur after cataract surgery.

More details at www.equinescienceupdate.com

Catching things from horses

Two unusual cases of horse to human transmission of bacterial infections remind us of the importance of good hygiene practices when handling horses.

One report from the Netherlands concerns the suspected transmission of Methicillin-resistant Staphylococcus aureus (MRSA) type ST 398, from a foal to a 16 year old girl. The girl, who was confined to a wheelchair, developed an infected wound from which a strain of MRSA, identified as belonging to type ST398, was isolated.

Investigations into the source of the infection showed that the girl had had intensive contact with a Friesian foal. She had not been admitted to hospital in other countries, nor had she been in contact either pigs or calves - the common source of human infection with this type of MRSA.

Swabs from other members of the girl's immediate family and other animals in the household were negative for MRSA

The type of MRSA involved,  ST398, is one which is associated with livestock and has been spreading in Europe and North America. It is the most common type of MRSA identified in horses in the Netherlands.
 
The authors suggest that the foal was the most likely source of the infection. In fact, the foal itself had been hospitalised in an equine clinic two months earlier for treatment of a wound infection.

Another report describes a surgical operation that became infected with Streptococcus equi.

S. equi, the cause of strangles in horses, is a cause of great concern to many horses' owners, but is rarely a danger to humans or other domestic species.

The patient, a professional racehorse trainer, underwent treatment for an aortic aneurysm - a condition in which the walls of the main artery leaving the heart are weakened and balloon outwards. If untreated there is a risk of sudden rupture leading to sudden death.

A specialised endovascular technique was used, in which a stent, a tubular framework,  was inserted into the femoral artery in the groin, and passed up the artery until it came to lie within the affected vessel.

The stent became infected and the causative organism was identified as Streptococcus equi.

Read more at www.equinescienceupdate.com

Faecal egg counts after tapeworm treatment

It may be more useful to look for tapeworm eggs the day after treatment rather than before. Research carried out by Johanne Elsener of Wyeth Animal Health and Alain Villeneuve of the Faculté de Médecine Vétérinaire, Université de Montréal looked at whether treating for tapeworms one day before carrying out a faecal examination improved the chance of identifying infected animals

The study involved horses of differing ages on a single stud farm - from weanlings to adult breeding mares and stallions.

All horses were presumed to be naturally infected with Anoplocephala perfoliata - as tapeworm-infected animals had been identified previously on the farm.

The horses were weighed and dosed according to weight.

The researchers examined faecal samples before and 24-48 hours after treatment with a paste containing praziquantel (and moxidectin). Faecal samples were examined using a modified Wisconsin sugar centrifugation technique - performed by a technician who was unaware of the treatment given to each .horse.

Overall, the researchers found that they were twice as likely to detect tapeworm eggs in the faeces of horses 24 - 48 hours after treatment with praziquantel than they were before treatment.

In adult horses (mares and stallions) the difference was statistically significant. Young horses (weanlings, yearlings and two year olds) showed a numerical increase in positive horses after treatment, but the difference was not statistically significant.

The two-year old horse group had the highest proportion of positive faeces, (66% horses were positive before treatment)

The researchers conclude that sampling after treatment may give a better idea of the true prevalence of tapeworm infection.

More details at equinescienceupdate.com

Does soaking make hay safer for laminitics?

An important part of treatment and prevention of laminitis is to limit the water soluble carbohydrate (WSC) intake. To achieve this, access to pasture is restricted and the horse or pony is fed hay instead.

But even hay may not be safe for horses with laminitis. Most authorities suggest that horses and ponies prone to laminitis or with insulin resistance should ideally receive hay that has a water soluble carbohydrate concentration not exceeding 100g/kg on a dry matter basis (DM)

However, in northern Europe pasture grasses often contain high levels of WSC (>300g WSC/kg DM), which may result in hay with WSC content up to 200g/kgDM.

It is often suggested that soaking the hay may reduce its water soluble carbohydrate content and thus make it safer for laminitis-prone horses and ponies. However, the studies that have supported this approach have often used large quantities of water and, as well, the hay may have been chopped prior to soaking.

Often owners do not go to such lengths. What is the effect of soaking hay when carried out according to common practice?

Dr Annette Longland, Clare Barfoot and Dr Pat Harris conducted an investigation into whether the degree of soaking that is in common use in the UK would have an effect on the WSC content of various hays.

The study looked at the loss of WSC and crude protein from a range of British hays, which were either shaken or left compacted in the "flake" and then soaked in just enough water to cover the hay, for various lengths of time.

The authors found that soaking hay for up to 16 hours produced variable and incomplete loss of WSC.
As would be expected, the dry matter content of the hays fell after soaking - there was a significant reduction in DM content after 20 minutes soaking, and a continued fall with longer periods of soaking.

However, regardless of the duration of soaking or whether the hay was shaken up or left compacted the WSC content of most of the hays remained above the recommended limit for laminitics of 100g/kgDM.

The researchers found no significant difference between the compacted or shaken hays. They conclude that soaking cannot be relied on to make hay suitable for feeding to laminitic horses.

They recommend that hay for animals prone to laminitis be analysed for WSC content, and only hay that is low in WSC is fed to horses prone to laminitis. Soaking can be used as an extra safeguard.

How does a brumby stallion spend his day?

Magdalena Zabek's latest report on the feral horses of central Australia is now available. Click here to read

Research confirms effectiveness of grazing muzzles

Using a grazing muzzle appears to be more effective than restricting access to pasture, for reducing the amount of grass eaten by ponies, according to a recent study.

Pasture intake by the ponies grazing for three hours without muzzles averaged 0.8% (with some eating close to 1%) of their bodyweight, which is the equivalent of up to two thirds of the recommended daily dry matter intake  for many ponies on restricted diets.

In contrast, the pasture intake of the ponies when wearing muzzles was around 0.14% of bodyweight over three hours, representing an average reduction of 83% compared to when they were not wearing muzzles.

Read more at www.equinescienceupdate.com

Making sense of flexion tests

Flexion tests are often used as part of a prepurchase examination or a lameness work-up to evaluate lameness or assess the likelihood of future lameness problems. But what does a positive flexion test tell us about which structures are involved?

Research published in the Equine Veterinary Journal suggests that the fetlock is probably responsible for a positive response to flexion test of the lower limb. Structures below that joint are less likely to be involved.

Dr Clodagh Kearney and colleagues conducted a study on eight warmblood horses. These were all clinically sound, but had gone lame after being subjected to a flexion test of the lower limb. Flexion tests were performed under standardised conditions.

The response to the flexion test was assessed after performing various nerve blocks, which desensitised different regions of the limb. One clinician performed the nerve blocks; others performed the flexion tests and assessed the degree of lameness. So the clinicians assessing the lameness did not know which nerve block had been carried out (or on which leg).

They found that a nerve block of the palmar digital nerves, just above the cartilage of the distal phalanx, had minimal effect on the lameness induced by the flexion test. A nerve block just below the fetlock at the level of the distal abaxial sesamoid bones produced a similar response. However, there was a marked improvement in flexion test induced lameness following a low four point block just above the fetlock.

The researchers conclude that the fetlock joint and surrounding structures contribute strongly to the outcome of a flexion test of the lower limb in a non lame horse. "From a clinical point of view, it is reasonable to suggest that the flexion test of the distal limb may be sensitive for investigating the metacarpophalangeal joint region, but may be less relevant for structures distal to this joint."

Read more at www.equinescienceupdate.com

Treponemes found in canker lesions

Japanese research has found evidence of treponemes in equine canker by looking for specific portions of RNA characteristic for the organisms.

Canker is a chronic proliferative condition of the horse's foot - affecting the frog and bars and sole. In severe cases it may extend to involve the hoof wall. Similar conditions in cattle and sheep have been shown to be associated with spirochete bacteria - in particular treponemes.

Dr Kyaw Kyaw Moe and colleagues examined samples from lesions in two horses and compared them with samples from an unaffected horse.

They found spirochetes in microscopic sections of the canker lesions. They also found 114 clones in the affected horse samples and none in samples from normal horses.

The clones could be classified into 19 separate groups - corresponding to many different treponemes, including those implicated in bovine papillomatous digital dermatitis.

Despite this the researchers were unable to culture the organisms. This is not surprising as treponemes are slow growing and are often overgrown by more rapidly growing bacteria.

The research confirmed the presence of treponemes in canker lesions in two horses and their absence in a normal horse. However, as the study was based on only a couple of cases, the researchers could not confirm that treponemes are the cause of canker - further work is required involving more cases.

Read more at equinescienceupdate.com

Effect of psyllium on glucose and insulin

Psyllium, a sort of "super-bran", is already used in horses, particularly for treatment and prevention of sand colic. When mixed with water, it swells to up to 10 times its original volume, turning into a jelly-like substance which is thought to ease the passage of sand through the digestive tract.

Researchers at Montana State University conducted a trial to see if adding psyllium to a horse's diet had an effect on glucose and insulin metabolism. It had been noticed previously that psyllium had a beneficial effect on insulin sensitivity, when taken by people with insulin resistance. So they wanted to investigate whether a similar effect occurred in horses.

They used 16 healthy horses (8 mares and 8 geldings), which they divided into 4 groups of 4, each containing 2 mares and 2 geldings. All horses were fed a diet of mixed grass hay and a commercial whole grain feed twice a day. Psyllium pellets were added to the grain ration of three groups at 90g, 180g, or 270g daily. The fourth group received the same diet, but without added psyllium.

On the 60th day the researchers withheld food from the horses overnight. In the morning they collected blood samples before the morning feed and then every 30 minutes for six hours, to monitor the blood glucose and insulin concentrations.

The researchers found that on average, horses that had been receiving psyllium for 60 days had lower average peak glucose levels after feeding and lower average glucose levels. Psyllium-fed horses also had lower peak insulin levels and lower average insulin levels after feeding compared with horses that had not received psyllium.

Dr Shannon John J Moreaux, Assistant professor of Equine Science at Montana State University, and one of the research team commented. "Psyllium could be especially beneficial to obese, insulin-resistant horses, or horses that are predisposed to developing laminitis because of metabolic syndrome". He added that it was commercially marketed and readily available to horse owners, and when fed daily, may help to maintain lower post-feeding blood glucose and insulin levels.

This was a small study carried out using normal horses. Before we can conclude that psyllium will benefit insulin resistant horses, further research is needed using affected horses.

However, if it proves to be effective in insulin resistant horses it could provide a useful addition to the strategies available for managing this condition.

Read more at equinescienceupdate.com

Is your vet a health risk?

Vets that work with horses are more likely than other vets to carry methicillin-resistant Staphylococcus aureus (MRSA), according to an Australian study.

The researchers, led by Dr David Jordan, collected nasal swabs from 771 individuals, who were also asked for details of the type of work they did and with which species.

Analysis of the data showed that veterinarians that worked mainly or exclusively with horses were more likely the carry MRSA in their nostrils.

MRSA was present in 5.8% of those taking part in the study. However, the data revealed differences depending on the type of work the individuals performed.

Positive swabs were obtained from 11.9% of veterinarians who spent a lot of their time on horse work. (This was 13 times that of the vets involved in industry or government work. Less than 1% of them had positive swabs).

The figures were even higher among people who worked only with horses.  The results showed that 21.35% of them had nasal swabs positive for MRSA. (They were 23 times more likely to have their nostrils colonised by MRSA than were vets working for government or industry.)

Considering the extent of carriage of MRSA and the seriousness of the disease it can cause in humans and animals, Dr Jordan recommended that vets should take more precautions to prevent the spread of MRSA

"The higher than normal prevalence of MRSA carriage among veterinary clinicians in Australia is a cause for concern in the profession and warrants further investigation for specific risk factors, particularly for vets who work with horses"

He suggests that guidelines specific for equine work are needed. These should include: "enhanced personal hygiene during handling of animals; better sanitary management of premises, equipment and waste; greater awareness of biosecurity during handling and surgical procedures; and reform of use of antibiotics - especially those of importance in human medicine such as the fluoroquinolones, third generation cephalosporins and gentamicin."

Read more at www.equinescienceupdate.com

Hendra virus vaccine progress

Australian scientists have succeeded in developing an experimental vaccine to protect horses against Hendra virus.

Hendra virus (HeV) was first isolated in September 1994 from an outbreak at a training complex in Hendra (a suburb of Brisbane, Queensland, Australia) after which the virus was named.

During that initial outbreak 14 horses died. Seven other horses were found to have been infected and were humanely destroyed. Two humans were affected, one of whom died.

In five of the 14 known outbreaks, the infection has spread to people. The virus has killed four of the seven people infected.

Fruit bats (Pteropus spp), commonly known as flying foxes, have been identified as the natural host for the Hendra virus.

“Our trials so far have shown that the vaccine prevents the infection of horses with Hendra virus,” said Dr Deborah Middleton from the Australian Animal Health Laboratory (AAHL).

Stopping the disease in horses could also help protect people from the disease.

"All the human infections have come from contact with infected horses," Dr Middleton explains. So if you can control the disease in horses, you break the transmission cycle to people as well as protecting the health of horses.

Studies so far have shown that the vaccine will prevent horses becoming infected. It also protects them from developing the disease and shedding the virus.

Further work, including field trials and product registration, is still required. However, if all goes well, the vaccine may be available as soon as 2012.

Dr Barry Smyth, President of the Australian Veterinary Association, said that both vets and horse owners would welcome the news on the vaccine.

“It’s important that veterinarians and horse owners continue with precautions that reduce the risk of spreading the virus and that they report suspected cases immediately,” Dr Smyth said.

Read more at: www.equinescienceupdate.com

Saddle research uncovers new theory in asymmetry

The Saddle Research Trust (SRT), believe they have discovered a new theory in rider asymmetry, which they feel will have implications for equine performance and welfare.

Following a series of pilot studies carried out in conjunction with educational establishments throughout 2010, the charity claims to have evidence that highlights previously unidentified areas and measurable characteristics of saddle performance.

Anne Bondi BHSI, Director for the trust explains: “The initial objective of our early pilot studies was to measure the effect of the rider asymmetry using a variety of scientific measuring systems open to the trust. It soon became apparent that a more complex pattern of interaction was occurring, one that could not just be explained by a rider sitting crookedly.”

Humans are not perfectly symmetrical, and most riders are aware of being right or left handed. This ‘handing’ often creates a loss of symmetry in the rider in the vertical plane.

“After observing this common occurrence we began to examine further the effect the saddle has on the rider and their posture” she continues.

A similar lack of symmetry also exists in the horse in the horizontal plane. The movement of a horse’s back and limbs creates movement in the saddle, generating an unstable platform for the rider. This forces riders to adopt a compensatory action - accentuating the already asymmetrical posture. The horse also compensates for carrying the asymmetrical rider by counterbalancing.

According to the SRT, this is far more complex than a ‘chicken and egg’ situation. It involves a mixture of symptoms involving asymmetries in the horse, rider and saddle, but more significantly the interaction between them.

"Our studies to date have shown a clear lack of synchronisation in this three-way interaction, and it is our understanding that the degree to which this occurs is greatly affected by saddle design and fit."

“We have raised many new questions about the effect of saddles on asynchrony, as well as identifying measurable characteristics in saddle performance. Although our work is in its infancy we believe it will have far-reaching effects on all levels of equestrianism.”

Read more at www.equinescienceupdate.com

Bedding dope test risk

Flunixin excreted in the urine may be ingested with bedding, risking prolonging the time taken to clear the drug from the body.

Owners and trainers should be aware that horses may recycle anti-inflammatory drugs such as flunixin in the stable environment. This may prolong the time the drug is detected in the urine - thus increasing the risk of positive dope test.

Flunixin is a non-steroidal anti-inflammatory drug commonly used in horses. The rules of many disciplines prohibit its presence in the blood or urine of horses on the day of competition.

Detection times have been established for some medications to help veterinarians advise owners and trainers on how long before a competition treatment should be withdrawn to minimise the risk of the drug being found in the urine. However, research in France shows that the problem can be complicated by horses absorbing flunixin from bedding that has been contaminated by urine containing the excreted drug.

Work at the Laboratoire des Course Hippiques, found that, even if bedding is removed completely and the floor brushed out, there is still a risk of a "rebound" increase in urine flunixin levels.

Dr Marie Agnès Popot and colleagues looked at the excretion profiles of flunixin in urine collected from horses under various systems of stable management. They gave flunixin as either a single intravenous dose (1mg/kg) or as an oral paste (0.5mg/kg twice daily for 3 days).

Horses were housed in stables from which the bedding was either completely removed on a daily basis, or only "skipped out" (removing only soiled bedding on a daily basis, and cleaned completely once a week.)

The largest rebound in urine flunixin concentration was seen in those horses kept in stables that were not cleaned completely on a daily basis. However, removing all the bedding and sweeping the floor could not totally prevent rebound in flunixin levels. The only circumstance in which a rebound in urine flunixin levels did not occur was when the drug was given intravenously and the horse was moved to a clean stable after 24 hours.

"Flunixin is mainly eliminated by renal clearance and a large amount of flunixin is eliminated in urine within the first 24 hours following administration" the researchers explain in a report in the Journal of Veterinary Pharmacology and Therapeutics. "Then, for horses housed in unclean boxes, the conditions  exist for the possibility of prolonged recycling; the only way to break recycling is to move the horse in  another separate box after the first 24 hour of treatment, rendering unavailable the flunixin excreted in the urine for the first 24 hour."

They conclude that attention to stable hygiene can drastically reduce the risk of spurious drug excretion profiles for drugs such as flunixin that are mainly eliminated in the urine.

Read more at www.equinescienceupdate.com