Investigating anaesthetic safety

 Despite improvements in anaesthetic techniques, there is still a significant risk of a horse dying under anaesthetic.

In 2002, the Confidential Enquiry into Perioperative Equine Fatalities (CEPEF), found the risk of death in horses (up to 7 days after anaesthesia) to be about 1 in 100, higher than in dogs and cats (about 1 in 1000). The perioperative mortality rate in man, for comparison, is one in ten thousand.

 

Anaesthetic drugs and procedures have advanced since then, but have they increased the outcome/ reduced the risk of perioperative mortality?

 

A new study of anaesthesia related fatalities in horses (CEPEF4) is now underway. 

 

The study will collect data from cases of general anaesthetic procedures, or standing sedation lasting longer than 15 minutes, in horses and donkeys from around the world.

 

So far, 70 clinics around the world have contributed information from 9000 cases, mostly from Belgium, United Kingdom, Australia, Ireland, France, Switzerland and Spain.

 

The prospective study aims to evaluate perioperative fatality rate and identify factors that increase or reduce the risk of mortality.

 

The project was presented to the Association of Veterinary Anaesthesiologists meeting in Dublin, 2020. A video of the presentation is available:

https://www.youtube.com/watch?v=Gg0tvW0UR24&t=183s

New equine rotavirus implicated in foal diarrhoea

Researchers at the University of Kentucky’s Maxwell H. Gluck Equine Research Center and the Veterinary Diagnostic Laboratory have made a preliminary identification of a novel rotavirus associated with diarrhoea in very young foals.

Foals often develop diarrhoea in the first two weeks of life.  Many cases respond well to routine treatment but some may develop life-threatening dehydration within a matter of hours.

 

This year, some farms in Kentucky have reported an increased number of cases of diarrhoea in young foals. 

 

The new rotavirus, identified by the scientists at the University of Kentucky, could not be detected using current diagnostic tests for equine Rotavirus A and appears to be different to the virus strain used in the currently available commercial vaccine.

 

Further work is underway to better characterise the virus and determine its role in the current outbreak of diarrheal disease. Additional investigations are also underway at UK to identify other possible causes, and researchers are sending out an epidemiological survey to farms to better understand the outbreak.

 

A test for the virus is now available. "We have now developed a real-time PCR assay to detect this new equine rotavirus B in fecal specimens," noted Dr Craig Carter, Director of the Veterinary Diagnostic Laboratory.

 

Both the Gluck Center and the Veterinary Diagnostic Lab recommend strict biosecurity protocols as the best protection strategy at this time.

 

For more information, see:

 

 http://news.ca.uky.edu/article/uk-gluck-center-and-industry-leaders-responding-uptick-foal-diarrhea-cases.

Can an owner questionnaire help monitor arthritic pain in horses?

Osteoarthritis (OA) is a major cause of chronic pain in horses but is an underrecognized and undertreated condition. Though often associated with advanced age, it can also occur in young horses. In addition to being painful, OA can severely curtail a horse's athletic career, and impact the bond between horse and owner if the condition limits a horse's ability to be ridden. Controlling it often involves a combination of medication and management change and relies on the ability to monitor the response and make adjustments accordingly.

A new study is testing to see if a simple questionnaire can help horse owners recognize and monitor signs of chronic osteoarthritis (OA) pain in their horses – helping their equine charges get earlier, more effective treatment and improving their quality of life. 

Dr. Janny de Grauw, from Utrecht University in the Netherlands, and Diane Howard, PhD, MSc., Equine Science Master graduate from the University of Edinburgh, in the United Kingdom, are the recipients of a Donor-Inspired Study grant from the Morris Animal Foundation, funded by long-time supporter, Dr. Wendy Koch. Dr. Koch, a veterinarian, has closely followed equine behaviour and welfare research over the years and wanted to increase the amount of funding available for studies in these fields.

To effectively treat pain, caregivers and clinicians need a way of monitoring and quantifying the amount of discomfort felt. However, a survey of horse owners in the United Kingdom found that owners have limited ability to identify pain and disease in their horses, underlining the need for a simple way of helping people to recognize chronic pain in their equine companions.

“As veterinarians, we want to treat horses with painful and debilitating conditions like OA as effectively as possible,” said de Grauw. “How well we can manage their condition critically relies on recognition of subtle signs of (worsening) pain by owners and caregivers, who can then seek help.”\

Under Dr. de Grauw’s supervision, Howard developed the 15-item questionnaire based on changes in horse behaviour through interviews with owners of horses diagnosed with osteoarthritis. The questions cover posture, facial expressions, movement and behaviour.

She will validate the questionnaire by having 60 owners of horses with chronic OA pain and 20 owners of horses without OA complete it. The owners with OA horses will complete the questionnaire twice in two days while their horse’s pain does not fluctuate, to evaluate how robust and reproducible the scoring instrument is. 

The research team hopes the easy-to-use questionnaire will help horse owners recognize when their animals are in pain and contact a veterinarian for appropriate treatment. It also may help owners monitor treatment effectiveness and pain progression over time, and guide owners and veterinarians in making quality-of-life decisions. 

“Many horses may deal with pain that is not recognized, particularly in its early stages,” said Dr. Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. “Giving their caregivers effective tools for detection, monitoring and decision-making has the potential for significant animal welfare impact.”

For more details, see: 

https://www.morrisanimalfoundation.org/article/osteoarthritis-pain-in-horses-questionnaire?

Lehi horse not as ancient as first thought

 Excitement generated by the finding of a horse skeleton in Utah thought to date from the late ice age was misplaced according to a new study. 

The pony sized skeleton was discovered in Lehi, north central Utah in 2018. It was first thought to have lived about 16,000 years ago as it was found lying amongst geological deposits from the last ice age.

Now further work using radio-carbon dating has shown that the remains are in fact a lot younger - dating from about 300 years ago. 

However, the disappointment of discovering that the horse was not an ice age relic was tempered by the insights it revealed into the place of horses in native American life. The work is reported in the journal American Antiquity.

William Taylor, assistant professor of anthropology at the University of Colorado Boulder, was sceptical that this was an ice age fossil. Although ancient horses were common in north America during the Pleistocene, they went extinct around the same time as other larger mammals such as mammoths.

His suspicions were raised by the presence of fractures of the vertebrae –  injuries not commonly found in wild horses, but typical in those having been ridden without a frame saddle.

The horse also had evidence of severe arthritic changes in several limbs.

Dental examination revealed that the horse was about 12 years old when it died. Radiocarbon dating showed that it lived up to about 300 years ago.

DNA analysis revealed that the horse was female. This, in combination with the signs of arthritic damage, suggested that the horse was being kept alive for breeding purposes after she had outlived her use for transport.

Analysis of sequential samples of tooth enamel for carbon, oxygen, and strontium isotopes led the research team to deduce that the horse was raised and tended within the region where it was found.

Taylor, lead author of the study, suggests that the horse likely died sometime after 1680, before European settlers moved into the Salt Lake region during the mid-19^th century.

 

For more details, see:

Interdisciplinary Analysis of the Lehi Horse: Implications for Early Historic Horse Cultures of the North American West. 

Taylor, W., Hart, I., Jones, E., Brenner-Coltrain, J., Thompson Jobe, J., Britt, B., . . . Roberts, P. 

American Antiquity, (2021) 1-21.

https://doi.org/10.1017/aaq.2020.109

To see Dr Taylor's exhibit "Horses in the North American West",  part of the  University of Colorado Museum of Natural History, go to:

https://www.colorado.edu/cumuseum/horses-north-american-west

Keeping horses safe from heat and humidity

 With the Tokyo Olympics due to take place shortly during the Japanese Summer, the Equine Veterinary Journal has compiled a collection of relevant articles covering the health and welfare of horses competing in hot and humid conditions.

The special online collection "Preparing for Tokyo Olympics" contains 11 papers and is available to read free of charge. It highlights the ground-breaking research that followed the 1992 Barcelona Olympics.

 

“This is not the first time that extreme heat and humidity has challenged the viability of Equestrian events at the Olympic Games,” said Christopher Elliott, who is Guest Editor of the collection. “It is vital that we learn from the past to ensure the welfare of equine athletes in the future.” 

 

Topics covered are:

 

• Physiological, metabolic and biochemical responses of horses competing in the speed and endurance phase of a CCI**** 3‐day‐event
• Physiological responses to the endurance test of a 3‐day event during hot and cool weather
• Physiological responses of horses competing at a modified 1 Star 3‐day‐event
• Adaptations to daily exercise in hot and humid ambient conditions in trained Thoroughbred horses
• Sweating rate and sweat composition during exercise and recovery in ambient heat and humidity
• Physiological responses of horses to a treadmill simulated speed and endurance test in high heat and humidity before and after humid heat acclimation
• Comparison between two post exercise cooling methods
• Contributions of equine exercise physiology research to the success of the 1996 Equestrian Olympic Games: a review
• An index of the environmental thermal load imposed on exercising horses and riders by hot weather conditions
• Use of the Wet Bulb Globe Temperature (WBGT) Index to quantify environmental heat loads during Three‐day‐event competitions
• Risk factors for exertional heat illness in Thoroughbred racehorses in flat races in Japan (2005–2016)

 

Professor Celia Marr, Editor of the EVJ, added: “Prevention is always better than cure: this special collection provides much excellent research and knowledge gained from previous events. We must ensure that we use it to best effect to keep the equine athletes competing in extreme climates in Tokyo this summer safe, cool, healthy and performing at their best.”

 

To read the articles, go to:

 

https://beva.onlinelibrary.wiley.com/hub/journal/20423306/homepage/sc_olympics

Assessing horses’ welfare by reading their minds

A horse’s brain waves can reflect their welfare state according to recent research.

Electrical activity in the brain varies with the state of arousal of the different parts of the brain and the electrical waves have been grouped into bands according to their frequency: eg delta (δ: 0−4 Hz), theta (θ: 4−8 Hz), alpha (α: 8–12 Hz), beta (β: 12–30 Hz) and gamma (γ: >30 Hz). 

 

Theta waves tend to predominate during calm and relaxed states, while an alert state tends to produce more gamma waves.

Mathilde Stomp and colleagues at the University of Rennes, France, devised a headband for horses, to record the resting electrical activity in the brain (EEG – electroencephalogram). Then, to see if there was an association with the horses’ welfare state, they compared the patterns of electrical activity with an assessment of the horses’ behaviour.

Eighteen horses involved in the study were maintained under either “restricted” conditions (living in riding school stables with a few hours daily turnout on pasture and regular work) and “leisure” (on pasture all year round, with occasional leisure riding.)

The researchers found that theta waves tended to predominate in both sides of the brain in horses in a more positive welfare state, whereas beta waves tended to predominate in horses showing signs  of compromised welfare. Horses in a good welfare state produced fewer gamma waves in the right side of the brain.

A full report of the work is published in Applied Animal Behaviour Science. The authors suggest that “bilateral and left hemisphere theta activity is a promising neurophysiological marker of good welfare in horses, while a bilateral or RH [right hemisphere] high production of gamma waves should alert about potential welfare alterations.”

For more details, see:

Brain activity reflects (chronic) welfare state: Evidence from individual electroencephalography profiles in an animal model.

M. Stomp, S. d’Ingeo, S. Henry, H. Cousillas, M. Hausberger.

Applied Animal Behaviour Science, (2021) vol 236, 105271.

https://doi.org/10.1016/j.applanim.2021.105271

Atypical myopathy toxins found in mare's milk

 Research shows that the toxins responsible for Atypical Myopathy can pass to the mare’s milk. This can present a potential risk to the foal and may have human health implications in places where mare’s milk is drunk in preference to cow’s milk.

A case of atypical myopathy was identified in a mare and newborn foal in Germany. The mare had been grazing pasture close to Acer pseudoplatanus trees (sycamore or sycamore maple).

 

Johannes Sander and co-workers in Hannover, investigated the case.  A report of the work is published in the Journal of Veterinary Internal Medicine.

 

The authors analysed a sample of the mare's milk for hypoglycin A, the main toxin responsible for atypical myopathy, and other metabolites.

 

They also examined samples of commercially available frozen mare’s milk (for human consumption) from six different suppliers across Germany.

 

The researchers found low levels hypoglycin A and significant levels of metabolites (methylenecyclopropylformyl glycine and carnitine)in the milk from the affected mare. High levels of acylcarnitines, (indicators of the metabolic damage caused by atypical myopathy), were also found. The authors point out that the milk sample was collected two days after the mare had been removed from the contaminated pasture, and suggest that the levels of metabolites in the sample indicate that hypoglycine A levels would likely have been higher at the time the foal was nursing. 

 

Methylenecyclopropylformyl glycine and carnitine were also detected in one of the six samples of commercial mares’ milk.

 

The authors conclude that maple toxins can pass through mare's milk.

 

They also warn that their findings have relevance in human health. Seeds and unripe fruit of plants such as ackee and lychee contain similar toxins, and may present a risk to breast fed children.

 

 

For more details, see: 

 

Detection of maple toxins in mare's milk

Johannes Sander, Michael Terhardt, Nils Janzen 

Vet Intern Med (2021) 606-609.

 doi: 10.1111/jvim.16004

Does not getting enough sleep affect horses’ memory?

A recent study examined the effect of environmental factors on equine sleep stages, and whether this would influence cognitive performance during a memory task.

As a prey species, horses have evolved to cope with short periods of rapid eye movement (REM) sleep and are known for their ability to sleep, or at least doze, (Non-REM sleep, NREM) while standing up. They still have to lie down for REM sleep which is only possible during recumbency due to the lack of muscle tone that occurs during this sleep phase. 

 

In research conducted at Aberystwyth University, Linda Greening and others investigated the effect of two different light regimes, and two different depths of straw bedding on sleep patterns in horses. They also looked at whether the differences affected the horses’ response to a memory test – basically remembering which of four buckets placed around an arena contained a feed reward.     

 

In a report in Applied Animal Behaviour Science, the authors describe how ten adult riding school horses were randomly assigned to two equal-sized groups for the five-week experiment. Each group experienced a combination of one of two light conditions (lights on or off overnight), and one of two bedding depth treatments (straw bed 15 cm or 5cm deep) for six days.

 

 The authors found that the duration of sleep stages was affected by both the depth of bedding and lighting conditions. Under sub-optimal conditions, horses tended to spend significantly less time recumbent for both NREM and REM sleep. This was compensated for by increased time in standing NREM sleep.

 

Sub-optimal lighting and bedding conditions did not have a significant effect on performance during the spatial memory test. The authors suggest that, “a more cognitively demanding task may be required to differentiate the performance-related consequences of different levels of sleep duration and quality.”

 

 

For more details see:

 

The effect of altering routine husbandry factors on sleep duration and memory consolidation in the horse

Linda Greening, Josh Downing, Daniella Amiouny, Line Lekang, Sebastian McBride

Applied Animal Behaviour Science

Volume 236, March 2021, 105229

https://doi.org/10.1016/j.applanim.2021.105229