Horses can distinguish between men and women based on the tone of their voice.

Recent research suggests that domesticated horses can use multiple senses, such as vision, and hearing, to identify human males and females. 

Several studies have shown that horses can recognise humans by associating their voice with their physical appearance. This ability to recognize a person, or object, based on information from multiple senses, such as sight, sound and smell, is known as “cross-modal recognition”. 

“To date, it remains unknown whether horses that are regularly in contact with humans are able to cross-modally recognize women and men. Thus, we sought to evaluate this ability in the current study.” wrote Chloé Gouyet and colleagues in the article published in Scientific Reports. 

“This study aimed to investigate whether horses are able to associate a woman’s voice with a woman’s face and a man’s voice with a man’s face, using a preferential looking paradigm.” 

In equine research, the “preferential looking paradigm” is often used to investigate whether horses have visual preferences for different stimuli. For example, researchers may present horses with pairs of images, such as a natural pasture scene set against a man-made environment, or an angry face compared with a happy face. By measuring which of the pair of images the horse spends more time looking at, researchers can infer the horse's preference. 

(c)Gouyet et al (CC BY 4.0)

The researchers explain: “We simultaneously presented two videos of women and men’s faces, while 

playing a recording of a human voice belonging to one of these two categories through a loudspeaker.” 

This procedure was repeated in six trials. The videos changed at each trial, so each horse saw six different women and six different men. “Our hypothesis was that horses would look preferentially at one of the videos depending on the vocal stimulus.” 

Analysis of the results showed that the horses looked significantly more towards the man’s face when hearing the male voice; and towards the woman’s face when hearing the female voice. The findings suggest that horses can associate women’s voices with women’s faces and men’s voices with men’s faces.

“Further investigation is necessary to determine the mechanism underlying this recognition, as it might be interesting to determine which characteristics horses use to categorize humans” the researchers suggest.

“These results suggest a novel perspective that could allow us to better understand how horses perceive humans.” 

 For more details, see: 

 Horses cross-modally recognize women and men Chloé Gouyet, Monamie Ringhofer, Shinya Yamamoto, Plotine Jardat, Céline Parias, Fabrice Reigner, Ludovic Calandreau & Léa Lansade 

Scientific Reports vol 13, 3864 (2023) 

https://www.nature.com/articles/s41598-023-30830-6

Funding available for Equine Assisted Services research

(c) Photojogtom Dreamstime.com

Proposals for research grants are invited for projects to investigate the impact of Equine Assisted Services (EAS).

Horses and Humans Research Foundation (HHRF), have announced the availability of up to $75,000 in research funding. and are now inviting applications.

HHRF specify that grant applications should include rigorous research proposals measuring the impact of the horse-human interaction on the wellbeing of the human participant including but not limited to the social, physical, cognitive, mental, and/or spiritual elements of the whole person.  

 

“All proposals undergo a four-tier review process completed by the Scientific Advisory Council. Preference will be given to investigators with solid credentials and research experience. The maximum award is $75,000 for up to two years. The winning proposal will have scientific merit, scientific and clinical significance, and relevance. “

 

Deadline for submission of proposals is Friday, May 26, 2023

 

Information for applicants, including the recently updated application and review guidelines, previously funded projects, and more are available at:

 

https://www.horsesandhumans.org

Compression therapy boosts lymphatic flow

(c) Drew Koch et al

Researchers from North Carolina State University have taken technology aimed at helping humans suffering from lymphedema and developed a medical device to aid horses suffering from the same condition. 

 There is a fine balance between fluid leaving the blood vessels and being taken up by the lymphatic system, which transports it from the tissues back to the bloodstream. Lymphedema occurs when that balance is disturbed and there is an accumulation of lymphatic fluid in the tissues of the limb. 

In a pilot study, Drew Koch and colleagues, found that the device, called the EQ Press, was successful in moving fluid up the limbs and into the lymph nodes. Its developers suggest it could lead to relief for horses with chronic conditions, as well as with temporary swelling due to injury or inactivity. 

“Across the board, horses are predisposed to lower limb swelling,” says Lauren Schnabel, associate professor of equine orthopaedic surgery at NC State and co-author of the study. “Lymphatic flow is driven by muscle contractions that circulate lymph fluid through the lymphatic system – horses are prone to lymphatic issues because they have very little musculature in the lower limbs.” 

The severity of the condition can vary widely – from temporary swelling due to restricted mobility, to lymphangitis caused by infections that can scar the lymphatic system. Treatment is often frustrating, but may include cold water, ice, bandaging and encouraging exercise. 

“Humans suffer from the exact same type of lymphedema horses do, but the difference is that human medicine has a very effective treatment option – pneumatic compression devices,” Schnabel says. “So, we wanted to create a horse-specific version of those devices and see if it would be similarly effective.”

Working closely with a company that manufactures human pneumatic compression devices, Schnabel developed the EQ Press in collaboration with former NC State veterinary student Irina Perdew. 

In the study, six healthy thoroughbreds were injected with a tracer isotope – a Tc-99m labelled sulfur colloid - at the coronary band in the front legs. The colloid is taken up and excreted through the lymphatic system. A specialised camera followed the movement of the isotope up the lymphatic system and into a lymph node in the upper limb, a process known as lymphoscintigraphy. 

Each horse underwent lymphoscintigraphy twice – once with treatment by the compression device on the front limbs and once without – randomized between treatment and control. 

In all EQ Press treated horses, the camera showed the tracer isotope moving from the lower limb to the lymph node in the upper limb within a 60-minute window. Of the control horses, only one showed that the tracer isotope was able to reach the lymph node in the same time. 

Overall, EQ Press treated horses had significantly accelerated lymphatic flow compared to untreated horses, recorded as both time for the marker to move out of the lower limb and time for it to reach the lymph node in the upper limb. Schnabel and the research team found the results encouraging and want to determine whether pneumatic compression treatment will be as helpful for horses as it is for humans. 

“Now we have compelling evidence that pneumatic compression treatments can accelerate lymphatic flow in healthy horses,” Schnabel says. “Our next step is to study the effectiveness of the EQ Press for treatment of horses with medical conditions such as lymphedema.” 

The open-access study is published in the American Journal of Veterinary Research. 

Schnabel is co-founder and chief medical officer of Vetletics, Inc., the company that manufactures the EQ Press. 

For more details, see: 

Pneumatic compression therapy using the EQ Press accelerates lymphatic flow in healthy equine forelimbs as determined by lymphoscintigraphy 

Drew Koch, Lauren Schnabel, Justin Reynolds, Clifford Berry. 

American Journal of Veterinary Research (2023) 

https://doi.org/10.2460/ajvr.22.12.0214

Can you help in a study to monitor arthritic pain?

(c) Silviu-Florin Salomia Dreamstime.com

Do you have an arthritic horse?  Could you spare a little time to take part in a study to validate
the use of a questionnaire for monitoring signs of chronic pain in horses with osteo-arthritis. 

Osteoarthritis (OA) is a major cause of chronic pain in horses yet it remains an under-recognized and under-treated condition. Despite its common association with advanced age, it can also affect young horses. In addition to being painful, OA can severely limit a horse's athletic career, and impact the bond between horse and owner if the condition limits a horse's ability to be ridden.

 

Diane Howard, PhD, MSc., a graduate of the Equine Science Master's program at the University of Edinburgh, has developed a 15-question survey based on interviews with horse owners whose animals suffer from chronic osteoarthritic pain.

 

The study will evaluate the questionnaire's efficacy in assisting owners to identify and monitor behavioural indications of pain in their horses.

 

Initial results,presented at the Horses Inside Out conference, are promising, but additional participants are required. To date, people completing the questionnaire have found it to be both helpful and straightforward to complete, with all participants able to finish it in less than five minutes.

 

The research, in collaboration with Dr. Janny de Grauw, from Utrecht University in the Netherlands, is funded by the Morris Animal Foundation.

 

“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, and to take part, please contact Diane Howard, at:

 

dianehoward@gmail.com

.

Why do horseflies avoid stripes?

 

(c) Martin How

Researchers at the University of Bristol have discovered the reason why horseflies tend to avoid attacking individuals with stripes, as opposed to those with big, solid dark patches. 

Their findings show that stark black-and-white contrasts and small dark patches are particularly
effective in preventing horsefly attack. Specifically, these features eliminate the outline of large, single-colour dark patches, which horseflies find attractive at close range. 

 

The team suggest that the thin back stripes serve to minimise the size of local features on a zebra that are appealing to the biting flies.

 

The research was led by Professor Tim Caro and Dr Martin How both from the University of Bristol’s School of Biological Sciences. An open access report of the work is published in the Journal of Experimental Biology.

 

 Prof Caro explained: “We knew that horseflies are averse to landing on striped objects - a number of studies have now shown this, but it is not clear which aspects of stripes they find aversive.

 

“Is it the thinness of the stripes? The contrast of black and white? The polarized signal that can be given off objects? So, we set out to explore these issues using different patterned cloths draped over horses and filmed incoming horseflies.”

 

The team found that tabanid horseflies are attracted to large dark objects in their environment but less so to dark broken patterns. All-grey coats were associated with by far the most landings, followed by coats with large black triangles placed in different positions, then small checkerboard patterns in no particular order. In another experiment, they found contrasting stripes attracted few flies whereas more homogeneous stripes were more attractive.

 

Professor Caro added: “This suggests that any hoofed animal that reduces its overall dark outline against the sky will benefit in terms of reduced ectoparasite attack.”

 

The team found little evidence for other issues that they tested, namely polarization or optical illusions confusing accurate landings such as the so-called ‘wagon-wheel effect’ or ‘the barber-pole effect’.

 

They conclude: “Our working hypothesis now is that horseflies are attracted to equid hosts owing to a combination of odour at a distance, then size of the animal contrasted against the sky or vegetation at a middle distance. But at close range, where they can no longer see the body's outline, flies make a visual switch to local features. If these are small dark objects contrasted against a light or white background, the horsefly no longer recognizes this as a host target and veers away. The contrast of stripes and their relatively small size are therefore the key elements of how stripes operate to thwart fly landings.”

 

Now the team want to determine why natural selection has led to striping in equids - the horse family - but not other hoofed animals.

Professor Caro added: “We know that zebra pelage – fur - is short, enabling horsefly mouthparts to reach the skin and blood capillaries below, which may make them particularly susceptible to fly annoyance, but more important, perhaps, is that the diseases that they carry are fatal to the horse family but less so to ungulates. This needs investigation.”

 

For more details, see:

 

Why don't horseflies land on zebras?

Tim Caro, Eva Fogg, Tamasin Stephens-Collins, Matteo Santon, Martin J. How

J Exp Biol (2023) 226 (4): jeb244778.

https://doi.org/10.1242/jeb.244778

Survey: medicines and horse health in Wales

(c) Miles Haegebaert Dreamtime.com

Horse owners across Wales are invited to take part in a survey: “Understanding Welsh horse
owner perceptions of medicines use and horse health care.”

The survey is run by scientists at Aberystwyth University as part of the Arwain DGC (Responsible Antimicrobial Use) project. Arwain DGC aims to prevent the spread of antimicrobial resistance (AMR) in animals and the environment in Wales. 

 

By improving productivity, animal health and welfare through new and innovative technology and ‘good practice’, the goal is to reduce the need to use antimicrobials such as antibiotics.

 

It is hoped that the survey will bring about a greater understanding of the how Welsh horse owners view medicine usage and aspects of horse health care. Lead researchers are Rebekah Stuart or Alison Bard.

 

“We hope this study will generate information that will help target future research, support and funding within the Welsh equine sector, as currently very little is known about Welsh horse owners’ views on these topics.”

 

“Our questions will explore how you view your relationship with your horse or horses, how they receive husbandry and health care and how you interact with your vet and other individuals regarding medicines use.”

 

 

For more details, and to complete the survey, go to:

 

 

https://aber.onlinesurveys.ac.uk/arwain-dgc-equinesurvey

Evidence that Vikings brought horses across the North Sea

Credit : Jeff Veitch Durham University

 Recent research claims to have found the first solid evidence that Scandinavians brought horses, dogs and other animals across the North Sea with them as early as the ninth century AD.

Vikings, who lived in modern-day Norway, Sweden, and Denmark, have a reputation as skilled raiders and warriors. As seafaring people, they travelled extensively from the late 8th to the early 11th centuries, establishing settlements in various parts of Europe and the North Atlantic.

 

It is likely that they acquired horses through conquest and raids. However, a study of cremated bones found at an archaeological site in the English midlands suggests that at least some of their horses had been brought with them from Scandinavia.

 

The findings are published in the scientific journal PLOS ONE.

 

Lead author Tessi Löffelmann, a doctoral researcher jointly working in the Department of Archaeology, Durham University, and the Department of Chemistry, Vrije Universiteit Brussels, said: “This is the first solid scientific evidence that Scandinavians almost certainly crossed the North Sea with horses, dogs and possibly other animals as early as the ninth century AD and could deepen our knowledge of the Viking Great Army.”

 

“Our most important primary source, the Anglo-Saxon Chronicle, states that the Vikings were taking horses from the locals in East Anglia when they first arrived, but this was clearly not the whole story, and they most likely transported animals alongside people on ships.”

 

The work was a collaboration between academics at the Universities of Durham and York in the UK, and the Vrije Universiteit Brussel, in Belgium. 

 

They explain: “The barrow cemetery at Heath Wood, Derbyshire, is the only known Viking cremation cemetery in the British Isles. It dates to the late ninth century and is associated with the over-wintering of the Viking Great Army at nearby Repton [ in present day Derbyshire] in AD 873–4.”

 

Fragments of cremated bone from the site were available for analysis: two adult humans, a child and a horse, dog and pig.

 

But how to tell where these cremated bony fragments originated?

 

Strontium analysis helps provide the answer. Strontium (Sr) is an element, related to calcium, that is taken up by plants, which are then eaten by animals. The ratio of strontium isotopes in the soil varies from one geographical location to another. 

 

Because strontium is so like calcium, it is taken up by the bone. The ratio of strontium isotopes in the bone reflects that of the soil of the area in which the animal lived.

 

The researchers explain: “The Sr isotope ratios (87Sr/86Sr) from the bones and teeth of an individual, who grows up while ingesting plants from the immediate surrounding area, should reflect the local biologically available Sr  (BASr). By measuring these ratios in plants from the ‘local area’, it is possible to define the local BASr and its variations around the site.”

 

Strontium ratios in one of the adults and the child showed that they could have been from the area local to the Heath Wood cremation site.

 

But the remains of the other adult and all three animals – a horse, a dog and what the archaeologists say was possibly a pig – had strontium ratios normally found in the Baltic Shield area [the geological region comprising Norway, Sweden, Finland, and parts of Russia].

As the human and animal remains were found in the same cremation pyre, the researchers believe the adult from the Baltic Shield region may have been someone important who was able to bring a horse and dog to Britain.

 

Professor Julian Richards, of the Department of Archaeology, University of York, who co-directed the excavations at the Heath Wood Viking cemetery, said: “The Bayeux Tapestry depicts Norman cavalry disembarking horses from their fleet before the Battle of Hastings, but this is the first scientific demonstration that Viking warriors were transporting horses to England two hundred years earlier.

 

“It shows how much Viking leaders valued their personal horses and hounds that they brought them from Scandinavia, and that the animals were sacrificed to be buried with their owners.

 

 

For more details, see:

 

Sr analyses from only known Scandinavian cremation cemetery in Britain illuminate early Viking journey with horse and dog across the North Sea

Tessi Löffelmann , Christophe Snoeck,  Julian D Richards , Lucie J Johnson,  Philippe Claeys , Janet Montgomery 

PLoS One (2023) Feb 1;18(2):e0280589.

https://doi.org/10.1371/journal.pone.0280589

Possible new approach to DDSP treatment

 Intermittent dorsal displacement of the soft palate (iDDSP) is a cause of exercise intolerance
and poor performance, particularly in horses involved in strenuous activities such as racing. 

In DDSP, the soft palate, which should fit snuggly around the larynx, flips out of position and obstructs the airway, limiting the horse’s ability to breathe.

 

Various techniques have been used to treat the condition; ranging from the conservative (such as tongue straps, crossed nose bands, glycerine on back of the tongue, treatment of other respiratory problems), to surgery.

 

Laryngeal tie forward (LTF) is a commonly used surgical treatment for the condition with reported success rates up to 80%.  Prosthetic sutures are placed between the thyroid cartilage and the basihyoid bone, to tie the larynx forward and fix it in place to prevent the soft palate dislocating and blocking the airway during exercise.

 

The operation is typically carried out under general anaesthetic, which involves some risk and expense. It has been suggested also that recovery from general anaesthetic may contribute to failure of the prosthesis (sutures). 

 

Clinicians at the University of Queensland School of Veterinary Science have described a series of cases in which they carried out the operation in sedated standing horses.

 

Natasha E. Lean and colleagues reported the work in a recent issue of Veterinary Surgery.

 

They performed Standing LTF in five experimental (normal) horses and five clinical cases with iDDSP. The procedure was carried out under endoscopic guidance, with the horses sedated and the surgical site desensitised with local anaesthetic. No major complications were encountered.

 

The response to surgery was assessed using radiography, and endoscopy. 

The authors conclude that standing LTF is “feasible, mitigates the risk of general anesthesia related complications and reduces cost.”

 

 

For more details, see:

 

Laryngeal tie-forward in standing sedated horses

Natasha E Lean, Albert Sole-Guitart, Benjamin J Ahern 

Vet Surg (2023) Feb;52(2):229-237.

 doi: 10.1111/vsu.13920 

Advances in imaging distal limbs

PET, CT and MRI images of navicular / middle phalanx. (c) EVJ

Radiography has been used for imaging horses’ legs for over a hundred years. Recent technological advances have
delivered new imaging modalities.

The publications Veterinary Radiology & Ultrasound (VRU), Equine Veterinary Education (EVE) and the Equine Veterinary Journal (EVJ) have combined forces to celebrate the evolution in equine imaging with a free special collection to reflect some of the most significant advances in distal limb imaging from the past five years.

 

Advances in Imaging of the Equine Distal Limb 2017–2022 comprises a total of 20 papers which have been selected by Mathieu Spriet, Ann Carstens and Tim Mair. It is accompanied by a comprehensive editorial from the EVJ summarising the major historical technological developments in imaging of the foot and fetlock, embracing all the modalities.

 

The evolution of computed tomography (CT) allows the imaging of the distal limb without anaesthesia. CT scanners are also now used in surgery rooms bringing significant progress in orthopaedic surgery.  Six papers look at advances in CT including addressing some of the challenges of the ring design of this modality.

 

Positron emission tomography (PET), the latest modality to be introduced to equine imaging, has opened a whole new field of possibilities for bone and soft tissue imaging in racehorses and sport horses. Five papers look at how PET brings functional information to the table, allowing early detection of abnormalities before the occurrence of structural changes and distinguishing between active and inactive lesions when structural changes are present.

 

MRI has been a mainstay in orthopaedic imaging for many years; six important studies are included in the collection and show how the optimisation of scanning techniques is constantly improving this modality. 

 

Ultrasound is steadily improving; one of the papers looks at the important technical evolution involving the imaging of limbs in non-weight bearing position as well as under the classic weight bearing position.

 

Radiographs remain the most commonly used imaging technique, despite the modality being more than 100 years old. One of the papers confirms why radiographs remain a valuable imaging tool.

 

The role of scintigraphy has decreased in the past 20 years with the emergence of advanced cross-sectional imaging, but it remains an essential tool especially for comparative imaging studies. One of the papers examines agreement between scintigraphy and MRI to identify the source of foot pain.

 

“The content of this virtual issue represents an amazing amount of new knowledge that with no doubt will contribute to improve equine welfare and safety,” said Mathieu Spriet. “With the increase availability and versatility of all the imaging modalities, the knowledge base appears to increase exponentially. We are very excited to see what the next five years will bring. We hope the readers will enjoy consulting this collection as much as we enjoyed putting it together.”

 

“During the past five years close to 100 equine imaging papers have been published between EVJ, VRU and EVE, covering a wide variety of topics,” said Professor Celia Marr, Editor of the EVJ. “The EVJ is proud to have been able to work collaboratively to bring this definitive distal limb imaging collection to life, giving clinicians easy access to some of the most pertinent work in this area.”

 

The virtual issue is free for 12 weeks and can be found at https://beva.onlinelibrary.wiley.com/doi/toc/10.1001/(ISSN)2042-3306.equine-distal-limb

Free webinars from Marion duPont Equine Medical Centre

 The Marion duPont Scott Equine Medical Center has announced a series of “Tuesday Talks” over the next few months.

 Topics to be covered are:

 

Tuesday, February 14:

Jennifer Barrett, DVM, Ph.D., DACVS, DACVSMR - “Let's Get Moving! Regenerative medicine for orthopedic injuries”

"From stem cells to blood-based biologics, the choices for treating tendon, ligament, and joint injuries are myriad. Learn the biology behind the therapies, most notably the evidence supporting their use."  

 

Tuesday, March 14: 

Elizabeth MacDonald, BVMS, MS, DACVIM (LAIM) - “The Scoop on Loose Poop: Equine Diarrhea”

"Diarrhea in the horse can range from mild chronic diarrhea to acute severe diarrhea. The common causes of diarrhea in the horse will be reviewed, along with ways to diagnose the underlying cause, and when to become concerned as an owner." 

 

Tuesday, April 11: 

Megan Marchitello, DVM - “Equine Respiratory Disease: It’s a lung story”

"An overview of the equine respiratory tract and common pathology".

 

Tuesday, May 9: 

Teresa Hopfgartner, DVM “Lumps and Bumps - Common Equine Skin Tumors”

"While cancer is not as prevalent in horses as it is in humans, cancers of the skin are fairly common in horses and most of them are easy to spot. We will be discussing the most common skin tumors in horses - sarcoids, squamous cell carcinomas and melanomas - in horses and discuss how (surgical) treatment is applied and what you can expect following treatment."

 

Each presentation starts at 7 p.m. (EST), will be about one hour long, and is free to attend. Although it is possible to attend in person, a webinar link is also available.

For more details, and to register, go to:

https://aimsbbis.vt.edu/tuesday-talks-2023

Effect of back flexion on kissing spines

(c) Nicole Ciscato Dreamstime.com

The importance of considering the horse’s posture when examining for kissing spines was
highlighted by a recent study. 

Impinging dorsal spinous processes (IDSP “Kissing spines”) can be associated with pain and discomfort, leading to behavioural and performance issues. However, not all horses with kissing spines show clinical signs and the condition may go unnoticed until it is found during a routine check-up or imaging.

 

Diagnosis typically includes radiographic examination of the back, to assess the spaces between the dorsal spinous processes of the vertebrae. 

 

A study by O’Sullivan and colleagues aimed to ascertain if the thoracic vertebral interspinous space distances were increased by using facilitated thoracic flexion to alter the posture in horses diagnosed with IDSP.

 

Carried out at the Veterinary Teaching Hospital of the University of Helsinki, seven horses, (four geldings and three mares) took part in the study. They were presented to the hospital for investigation of back pain or had a previous diagnosis of IDSP (with at least one interspinous space <4mm). Horses with previous surgical treatment of thoracic IDSP were excluded.

 

The researchers compared the radiographic appearance of two sets of radiographs of each horse. 

 

They explain: “All horses were made to stand in a square position, the head was held by the handler and the mouth was kept level with the point of the horse’s shoulder. This position was maintained throughout the initial and second set of radiographs.”

 

The first radiographs were taken in the horses’ spontaneous posture. For the second set, an investigator vigorously scratched along the sternum to produce a lift of the thoracic cage and reduce the lordotic posture of the thoracic spine. At the point of greatest postural change, the radiographer was instructed to take the image.

 

The digital images were anonymised by one investigator.  A second investigator measured the interspinous space and was therefore blinded to the horse and owner identification, as well as the posture of the horse (i.e., either spontaneous or thoracic flexion) when the images were taken.

 

The researchers found that stimulating the horse to flex the spine increased every thoracic interspinous space (IS) distance in horses with IDSP. Furthermore, the changes in IS distances were large enough to decrease IDSP by 1–3 grades.

 

“The largest difference was at the mid-thoracic spine (T7-T13), with a 2.1–3.1 mm change.” They add: “Specifically, the greatest median distance change was between T7-T8 and T12-T13 (3.1 mm and 3.0 mm, respectively).”

 

They suggest that including such a dynamic and functional evaluation in diagnostic examinations may aid IDSP decision making.

 

“The results of this small study demonstrated that the median distance between dorsal spinous processes of the thoracic spine increased following manual facilitation of thoracic flexion and resulted in a reduced thoracic spinal lordosis. The results support the need for a more dynamic and functional evaluation prior to a diagnosis of IDSP, particularly when radiographic grading based on this interspinous distance may result in invasive intervention.”

 

For more details, see:

 

The effect of manually facilitated flexion of the thoracic spine on the interspinous space among horses with impinging dorsal spinous processes of the thoracic vertebrae.

S. O’Sullivan, C.M. McGowan, J. Junnila, H.K. Hyytiäinen,

The Veterinary Journal, 2022, Vol 289,105909.

https://doi.org/10.1016/j.tvjl.2022.105909

(Open access article published under a Creative Commons licence)

Potential new marker for joint infection

(c) Virginia Dreamstime.com

Synovial infections, involving joints and tendon sheaths, are a potentially serious condition in
horses. Early diagnosis and treatment are essential. If not treated promptly, the infection can cause permanent damage to the joint with potentially career-ending and, indeed, life-threatening consequences.

 Usually, a diagnosis of joint infection is confirmed on the basis of synovial fluid analysis - typically looking at the white blood cell count and protein levels.

 

Scientists at the University of Copenhagen have been investigating the potential of neutrophil gelatinase-associate lipocalin (NGAL) as a marker for synovial sepsis

 

NGAL (also known – among other things- as Lipocalin-2) is a protein that is produced in response to injury or inflammation. It is involved in many processes in the body and plays a part in the non-specific immune defences. It acts to limit bacterial growth by sequestering iron, which is required for bacterial growth. Originally identified in neutrophils, it can be produced in other cells, such as kidney tubule cells, in response to damage. In human medicine it has been used for early diagnosis of acute renal injury, and it has been suggested to be a highly sensitive and specific marker of joint infection.

 

Stine Jacobsen and co-workers measured NGAL concentrations in 177 synovial fluid samples obtained from 152 horses suspected of having synovial infection. The aim of the study was to investigate NGAL concentrations in synovial fluid from horses with septic synovitis, horses without septic synovitis, and horses with uncertain status. A full report is published in Animals.

 

The authors explain that, based on the results from the clinical and diagnostic workup on the day of admission, horses were divided into three groups:

 

(1) septic synovitis, defined as a white blood cell count (WBC) >30 × 109/L leukocytes and one (or both) of the following: total protein (TP) >30 g/L and neutrophil granulocyte percentage (neutrophil%) >90. Horses were also defined as septic if there was a positive bacteriology result, (47 samples)

 

(2) non-septic, defined as WBC <5 × 109/L leukocytes, (103 samples), and 

 

(3) uncertain, defined as WBC >5 and <30 × 109/L leukocytes. (27 samples).

 

They found that concentrations of NGAL were significantly higher in the septic synovitis group than in samples classified as non-septic or samples with uncertain status, with median NGAL concentrations in the three groups being 1236, 16.8, and 266.4 µg/L, respectively. 

 

“NGAL discriminated nearly perfectly between septic and non-septic (area under the receiver operating characteristic curve 0.98, 95% confidence interval 0.95–1.00)” they report.

 

“The optimal cut-off value for maximal sensitivity (87.2%) and specificity (75.0%) to discriminate septic samples from those with uncertain status was 444.6 µg/L, with an area under the receiver operating characteristic curve of 0.85 (95% confidence interval 0.74–0.93).”

 

For 35 horses the scientists tested more than one sample taken over the course of treatment. They found that NGAL concentrations declined over time in horses undergoing treatment. 

 

They conclude “NGAL is a novel biomarker that seems to have great potential for identifying septic synovitis and for monitoring the response to treatment of synovial infection in horses.”

 

 

 

For more details, see: 

 

Gelatinase-Associated Lipocalin in Synovial Fluid from Horses with and without Septic Arthritis. 

Stine Jacobsen, Camilla Drejer Mortensen, Elisabeth Alkærsig Høj, Anne Mette Vinther, Lise Charlotte Berg, Ditte Marie Top Adler, Denis Verwilghen, and Gaby van Galen. 2023. Neutrophil 

Animals (2023) 13, no. 1: 29. 

https://doi.org/10.3390/ani13010029

(Open access article published under a Creative Commons licence)

Measuring weaning stress in foals

Foals take at least three weeks to adjust to weaning according to recent research.

(c) Rookie 72 Dreamstime.com

A study in Germany followed a group of foals from the day before weaning for the following three weeks. Kristin Delank and colleagues at the Ludwig-Maximilian-University of Munich aimed to demonstrate the medium-term effects of weaning on foals’ welfare.

 

To achieve this, they monitored the behaviour of a group of foals’ behaviour, and assessed levels of cortisol metabolites in their faeces, over a three-week period beginning the day before weaning. The group consisted of nine Arabian foals (six colts and three fillies), and one warmblood filly.

 

Observations took place at the state stud farm of Baden-Wuerttemberg in Germany. A full report is published by PLoS ONE.

 

“Until weaning, all foals were raised in a group with other dams and their foals, and the housing method was an open stabling with daily pasture time depending on weather conditions” the researchers explain. 

 

“The feeding consisted of grass on the pasture, hay ad libitum renewed three times a day, and for the dams concentrated feed twice a day in the stable. The foals also had access to the concentrated feed of their mothers.”

 

The foals were not all weaned at the same time, but in batches following the stud’s usual routine. Weaning was divided into three blocks, depending on the age and maturity of the foals - the first being in September, the second in October, and the last in November. 

 

“On the day of weaning, a veterinarian sedated the foals before they were transported to a breeding station 18 kilometers from the stud farm.”

 

Behavioural observations were carried out the day before, and the first full day after, weaning, and then at intervals over the following three weeks. An observer recorded the behaviour shown by the foals every five minutes throughout the eight-hour observation session (from 7am to 5pm.) 

 

The researchers report that, before weaning, foals spent most of the time moving. After weaning this changed, and they spent more time standing and resting. Weaned foals showed a significant increase in resting while standing. They also spent more time resting in a lying position during the day for the first eight days.

 

Four behaviours, (“aggressive behaviour,” “passive reaction,” “anxious behaviour,” and “vocalizing”) that were only seen after weaning, not before, were examples of stress-induced behaviours. (See figure) (The researchers suggest that a possible explanation for the increase in stress related behaviour on day 20 was that it coincided with a visit from the farrier.)

 

 

Stress-induced behaviours.

This graphic displays the total count of the shown behaviour for each day. All 10 foals are included. Note that observation day 1 is one day before weaning and observation day 3 one day after weaning.

https://doi.org/10.1371/journal.pone.0280078.g004

To gauge the stress experienced by the foal, the researchers measured the levels of a cortisol metabolite, 11,17-dioxoandrostane, in the faeces. This allowed them to get an indication of plasma cortisol levels without having to collect blood samples and disturb the foals further.

 

They found that all foals had a distinct hormonal stress response to the weaning process, as shown by a significant increase in faecal cortisol metabolite levels. The average cortisol metabolite level the day before weaning was 2.82 ng/g. this rose to 5.56 ng/g on the day of weaning, indicating stress experienced during the weaning process.

 

They report “The stress hormone levels increased until day 5 (i.e., three days after weaning), from day 9 the cortisol metabolite concentration shows a decrease while still being significantly higher (p = 0.001) than on day 0.”

 

Stress hormone levels were checked in six foals 17 days after weaning, when they were still higher than before weaning. Finally, at 19 days after weaning, three foals were tested, and were found to have faecal cortisol metabolite levels similar to the whole group of foals on the day before weaning.

 

The researchers conclude “the foals showed an expected behavioural development and an expected curve of cortisol metabolite values throughout the study. However, it seemed that the changes had not returned “back to normal” at three weeks after weaning. Therefore, we suggest that weaned foals need a minimum of three weeks to acclimate to the new situation.”

 

“It is not possible to accomplish weaning without producing stress in the foal. The goal must be to determine the process that provides the best long-term welfare for the foal.”

 

For more details, see:

 

Behavioral and hormonal assessment of stress in foals (Equus caballus) throughout the weaning process. 

K Delank, S Reese, M Erhard, A-C Wöhr (2023) 

PLoS ONE 18(1): e0280078. 

(Open access article published under a Creative Commons licence)

https://doi.org/10.1371/journal.pone.0280078

Use of blankets in North American horses

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Blanketing horses in the winter is a widely used, but fiercely debated practice.

Healthy horses maintain their body temperature within a narrow range (98.5°F to 101°F / 36.9°C to 38.3°C) despite a wide variation in environmental conditions.

 

In cold weather they use various physiological and behavioural methods to conserve body heat, such as piloerection, shivering, facing away from the wind. Eating roughage generates heat and so helps maintain body temperature.

 

A study, by Michelle L. DeBoer, at University of Wisconsin – River Falls, Department of Animal and Food Science, and colleagues, investigated the use of blanketing by North American horse owners.

 

They conducted a web-based survey looking at participant demographics, the use of blankets in winter, and the reasons why blankets were used or not.

 

A total of 1450 people completed the survey. Just over half of them reported that they blanketed their horses. A full report of the findings is published in the Journal of Equine Veterinary Science.

 

The researchers found that the use of blankets depends on discipline, housing, and management decisions.

 

Perhaps surprisingly, the geographical region of residence did not affect the frequency of blanket usage. The proportion of respondents who blanketed was similar in all regions, regardless of climate.

 

Those who chose to blanket most of their horses included those participating in English disciplines, professionals, respondents with less than six horses, and those who have been in the horse industry for less than 15 years. 

 

Horse professionals (those earning at least 50% of their annual income from horses) were more likely to blanket (63%), than non-professionals (37%).

 

The authors report that most common air temperature at which respondents blanketed was 0°C (14%) with some choosing to apply blankets at temperatures as high as 10°C (3%).

 

“However, the overwhelming majority chose to use blankets in response to precipitation, (rain, sleet, or snow)(85%) in addition to wind (58%).”

 

They conclude: “This survey highlighted the range of practices and opinions of North American horse owners in response to winter blanketing practices. Based on the results, there is comparable number of horse owners who chose to blanket versus those who chose not to blanket their horses.

 

“While there is consensus among horse owners regarding some blanketing topics, uncertainty continues to surround this management practice. Fortunately, most respondents indicated more research and subsequent dissemination of results on this topic would help horse caretakers better understand the necessity and potential advantages of blanketing”.

 

For more details, see:

 

Winter blanketing practices: An online survey of North American horse owners,

Michelle L. DeBoer, Aubrey L. Jaqueth, Ashley Tuszka, Krishona L. Martinson.

Journal of Equine Veterinary Science,(2022) Vol 113, 103911,

https://doi.org/10.1016/j.jevs.2022.103911.

(https://www.sciencedirect.com/science/article/pii/S0737080622000491)