Free tendon research articles from the EVJ

  

Horse with acute injury to left fore
superficial digital flexor tendon.
(Roger Smith) 

Horses are unfortunately prone to tendon and ligament injuries in the lower limb, and finding a universal treatment remains elusive. Nevertheless, significant scientific progress has been made in this area.

 

In the new virtual issue of the Equine Veterinary Journal (EVJ), guest editor Roger Smith has chosen 13 articles on the subject. 

 

There have been major advances in tendon and ligament disease research during the past 30 years. The 13 papers published in this new EVJ collection have been selected from the past five years to show progress in three key areas: pathophysiology – understanding why injuries occur and how they heal; progress in regenerative medicine; uncommon tendon and ligament injuries.

 

Tendon and ligament disease of the distal limb and the factors affecting treatment are complex, with variation in the severity of injury and variability in outcome between similarly affected horses. Understanding of the pathogenesis and improved diagnostic and predictive tools should enable the development of more effective treatments in the future.

 

• Microdamage in the equine superficial digital flexor tendon provides a review of what is currently known about tendon pathophysiology as well as the effect of ageing and the response to injury.
• Modelling the effect of race surface and racehorse limb parameters on in silico fetlock motion and propensity for injury provides further evidence of how mechanical loading can adversely influence the palmar tendons and ligaments.
• Ultrasound tissue characterisation of the superficial digital flexor tendons in juvenile Thoroughbred racehorses during early race training suggests that there are short-term changes with the onset of training, although it is not possible to know, at this stage, whether these changes have any relationship to the risk of injury.
• The use of sonoelastography to assess the recovery of stiffness after equine superficial digital flexor tendon injuries: A preliminary prospective longitudinal study of the healing process. This study potentially presents another way to monitor tendon healing and predict outcomes.
• Ultrasonographic-based predictive factors influencing successful return to racing after superficial digital flexor tendon injuries in flat racehorses: A retrospective cohort study in 469 Thoroughbred racehorses in Hong Kong: This work confirms that lesion size was predictive of outcome.
• Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses. This study provides important information to establish a clinically useful blood assay for tendon and ligament injury in the future.
• Retrospective analysis of local injection site adverse reactions associated with 230 allogenic administrations of bone marrow-derived mesenchymal stem cells in 164 horses. This work reports the highest frequency of reactions for synovial cavities and the injection of collateral ligaments of the distal interphalangeal joint.
• Ultrasound-guided injection of the cranial tibial artery for stem cell administration in horses reports an alternative delivery of stem cells via the cranial tibial artery to hindlimb structures where intralesional treatment is not possible.
• Extracellular vesicles from equine mesenchymal stem cells decrease inflammation markers in chondrocytes in vitro investigates how MSCs potentially act.
• Retrospective analysis of oblique and straight distal sesamoidean ligament desmitis in 52 horses includes a technique for optimising ultrasonography for imaging oblique DSL injuries.
• Magnetic resonance imaging and histopathological evaluation of equine oblique sesamoidean ligaments raises the question of whether many of these ligament injuries are being missed in practice.
• Magnetic resonance imaging following regional limb perfusion of gadolinium contrast medium in 26 horses considers how this method may enhance the identification of pathology within the foot.
• Chondrosesamoidean ligament enthesopathy: Prevalence and findings in a population of lame horses imaged with positron emission tomography. This study looks at how this new diagnostic technique may identify a new soft tissue injury within the foot.

 

“The field of tendon research is generating a healthy amount of quality research to counter the commonly held belief that there is nothing better than a double helping of God and time,” said Roger Smith. “Bit by bit we are moving closer to the holy grail of ideally preventing, or successfully treating, these injuries.”

 

“This collection provides an essential educational insight into the significant progress that has been made in tendon and ligament disease research over the past five years,” said Professor Celia Marr, Editor of the EVJ. “By giving veterinary practitioners the opportunity to understand the science and the variables behind why a specific treatment may work is a fundamental step towards the ultimate goal of reliable treatment success.” 

 

The virtual issue can be found at 

https://onlinelibrary.wiley.com/doi/toc/10.1001/(ISSN)2042-3306.tendoninjury 

and will be free to view until 27 February 2024.

Research highlights limitations of non-contact infrared thermometers

According to a recent study conducted by the Department of Large Animal Clinical Sciences at Texas A&M University in College Station, TX, non-contact infrared thermometers may not serve as a viable alternative to rectal thermometry for detecting fever in horses.

 Body temperature is a crucial vital sign used for assessing health and is important for monitoring horse health and implementing biosecurity measures within groups of horses. While rectal temperature remains the gold standard for accuracy, its use can be met with resistance from horses, posing potential danger for the operator.

 

Non-contact infrared thermometers have been considered as an alternative, providing quick and convenient temperature readings without direct contact. However, these thermometers offer a rapid assessment of surface temperature, and their readings may not closely reflect the core body temperature compared to rectal thermometers. Environmental conditions and the presence of a thick hair coat can further influence their accuracy.

 

The research, conducted by Leslie Easterwood and Noah D. Cohen from the Department of Large Animal Clinical Sciences at Texas A&M University, involved a comparison of rectal temperatures with recordings obtained using a non-contact infrared thermometer in 142 Quarter Horse horses and 34 Quarter Horse foals. Measurements from the non-contact infrared thermometer were collected from the forehead or neck, while rectal temperatures were recorded separately for each horse and foal.

 

The study revealed that the readings obtained by the non-contact infrared thermometer demonstrated good reliability in terms of measurement repeatability. However, these readings did not align well with rectal temperatures. Notably, there was a substantial negative bias, with adult horses displaying non-contact infrared thermometer readings nearly 2°F lower than rectal temperatures. This difference was more pronounced in foals, where the average difference exceeded 3°F.

 

In conclusion, the researchers assert that the substantial and inconsistent bias observed with the non-contact infrared thermometer indicates that these devices may not be a suitable substitute for rectal thermometry when aiming to obtain valid estimates of core body temperature in horses.

 

 

For more details see:

Agreement of Temperatures Measured Using a Non-Contact Infrared Thermometer With a Rectal Digital Thermometer in Horses,

Leslie Easterwood, Noah D. Cohen

Journal of Equine Veterinary Science,(2023) Vol 123,104243,

https://doi.org/10.1016/j.jevs.2023.104243

Effect of different hay feeders on behaviour

 Horses, being continuous grazers, have a natural inclination to feed steadily. Feral and wild horses may spend about 16 hours per day grazing. 

Allowing domesticated horses free access to roughage aligns with their natural feeding behaviour, representing a potentially optimal approach for horse health and welfare.

However, there are instances where restricting their food intake becomes necessary for management or health reasons. Nevertheless, such restrictions may impact their welfare and behaviour.

 

Implementing tools like hay-nets/bags and slow-feeders may prove helpful in decreasing food waste, extending the time horses spend consuming roughage, and potentially reducing undesirable behaviours.

 

The introduction of automatic hay boxes, providing scheduled feeding times throughout the day, contributes to minimising food waste. Despite this advantage, timed feeding through these devices may lead to abnormal behaviours in horses due to limited access to roughage.

 

A recent study evaluated the impact of three different hay feeders and the availability of roughage on horse behaviours in dry feed lots. The goal was to identify improved feeding techniques that could optimize feeding management, diminish abnormal behaviours, and improve the overall welfare conditions of horses in equine establishments.

 

Fifteen healthy thoroughbred cross horses from the Polo Club at Colorado State University participated in the research, employing a 3x3 Latin square design. The study comprised three groups, each consisting of five horses, with each group undergoing 15 days of one of the three treatments: free choice hay, slow feeder, or box feeder. At the conclusion of each treatment period, the horses underwent weighing, and blood samples were collected to monitor cortisol levels. Behaviour was  monitored throughout the final day of each treatment session.

 

The research, funded by Morris Animal Foundation, is published in Journal of Equine Veterinary Science.

 

Lead author, Jéssica Carvalho Seabra, said “Taking care of horses means more than just giving them a place to stay, food and water. It means giving them an environment where they can do things that are part of their natural behaviour like grazing.”

 

The researchers found that horses using automatic boxes and slow feeders consumed less and exhibited slower weight gain, indicating effective regulation of food intake. 

 

Horses with the freedom to choose when to eat had the highest hay utilization and weight gain rates, suggesting that this approach might not be optimal for overweight horses.

Horses with access to free choice feeding or a slow feeder spent more than half their day doing natural activities such as foraging. 

 

In contrast, horses using box feeders spent only about a quarter of their day eating, leading to increased time spent standing, sniffing the ground, and consuming their own faeces.

Furthermore, horses using the box feeder displayed more signs of aggression. During the study, the researchers noticed that horses became more aggressive as the feeders' size decreased and access to the food became more difficult. To address this issue, researchers recommend ensuring adequate space for each horse to eat without feeling crowded, especially when providing a limited amount of food.

 

"Selecting the right feeding technique can extend the time horses engage in natural behaviours, reducing the incidence of chronic stress and potentially curbing the emergence of abnormal and stereotypic behaviours in the long run," Carvalho Seabra said.

 

For more details, see:

 

Jéssica Carvalho Seabra, Tanja Hess, Marcos Martinez do Vale, Katherinne Maria Spercoski, Ryan Brooks, João Ricardo Dittrich,

Effects of Different Hay Feeders, Availability of Roughage on Abnormal Behaviors and Cortisol Circadian Rhythm in Horses Kept in Dry Lots,

Journal of Equine Veterinary Science (2023) Vol 130, 104911,

https://doi.org/10.1016/j.jevs.2023.104911.

Prevalence of laminitis in Norwegian ponies

New research highlights the problem of laminitis in the Norwegian Nordlandshest/Lyngshest pony breed.

Ponies, in general, are prone to laminitis and field observations suggest Norwegian breeds are no exception

 A recent study by Sigrid Lykkjen, Ingrid Hunter Holmøy from the Faculty of Veterinary Medicine at the Norwegian University of Life Sciences, and Linda Koldal Stenbakk from the Forus Hesteklinikk, sheds light on the prevalence and risk factors associated with laminitis within this pony breed. A full report of the study is published in Acta Veterinaria Scandinavica

 

The Nordland or Lyngshest, native to Norway, is typically small to medium-sized, standing at 12 to 14 hands (48 to 56 inches or 122 to 142 cm) at the withers. With a compact and muscular build, these ponies are well-suited for tasks in challenging mountainous terrains, commonly employed in riding, driving, and therapeutic riding programs.

 

The study aimed to assess the prevalence and risk factors for laminitis in the Norwegian Nordlandshest/Lyngshest pony breed. To address the question, the research team used questionnaires distributed among members of the Norwegian Nordlandshest/Lyngshest breed association..

 

Analysis revealed age, sex, and regional adiposity as notable risk factors for laminitis. Moreover, the level of exercise and outdoor housing was significantly correlated with a reduced prevalence of laminitis.

 

For horses over nine years old, the lifetime prevalence of laminitis approached 20%. However, the overall lifetime prevalence across the entire population was comparatively lower. The researchers attributed this lower prevalence to the study's inclusion of a substantial number of young animals (24% aged five years or less), suggesting their contribution to the overall lower incidence of laminitis.

 

In conclusion, the researchers emphasize that laminitis poses a considerable welfare challenge within the Nordlandshest/Lyngshest pony breed.

 

“The identified risk factors, namely age, sex, and regional adiposity, underscore the importance of heightened diagnosis and monitoring of EMS/insulin dysregulation in the breed. Additionally, the findings highlight the necessity for enhanced owner education and awareness of strategies aimed at reducing the risk of laminitis.”

 

For more details, see:

 

Prevalence and risk factors for laminitis within the Norwegian pony breed Nordlandshest/Lyngshest

Sigrid Lykkjen, Linda Koldal Stenbakk & Ingrid Hunter Holmøy 

Acta Veterinaria Scandinavica (2023) vol 65, Article number: 22 

Revealing the silent reservoir: Horses and the potential threat of Leishmaniosis

 Leishmaniasis, a zoonotic disease capable of transmission from animals to humans, has long
been acknowledged as a significant public health concern. The World Health Organisation reports that over one billion people reside in areas endemic to leishmaniasis, placing them at risk of infection. The disease manifests in three distinct syndromes in humans: cutaneous, mucocutaneous, and visceral. Annually, there are approximately 30,000 new cases of visceral leishmaniasis and over one million new cases of the cutaneous form. Remarkably, leishmaniasis ranks as the second leading parasitic cause of death worldwide, following malaria.

The causative agent of leishmaniasis is an intracellular protozoan parasite known as Leishmania spp., transmitted through sandflies. Traditionally, dogs have been identified as the primary reservoir, but recent research suggests the involvement of other species in the transmission cycle. 

 

Infected horses may exhibit signs of cutaneous leishmaniasis, manifesting as nodules on various body parts such as the head, ear, scrotum, legs, and neck. These lesions, which can be singular or multiple, often present with ulceration. However, some horses may carry the infection without displaying any visible signs, potentially serving as silent reservoir hosts

 

As our understanding of the dynamics of leishmaniasis transmission expands, it becomes increasingly important to consider a variety of animal species, including horses, in efforts to mitigate the impact of this disease on both animal and human populations.

 

Researchers from the Veterinary Faculty at Universidad Cardenal Herrera-CEU Valencia, Spain, conducted a study aimed at elucidating the potential role horses may play in the transmission of leishmaniosis, a parasitic disease. Lola Martínez-Sáez and her colleagues undertook an analysis of the prevalence and factors associated with L. infantum infection in seemingly healthy horses. A full report of the work is published in the online journal Animals.

 

The team gathered epidemiological data and serum samples from 167 apparently healthy horses in the Valencia region of eastern Spain. They used an enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (PCR) to assess the presence of L. infantum during two distinct periods: December 2022 to January 2023 and May 2023 to June 2023.

 

The results revealed that 27.5% of apparently healthy horses tested positive for anti-leishmania antibodies, and infection was confirmed through real-time PCR. Interestingly, horses with a calm temperament and those residing outdoors exhibited a higher prevalence of infection.

 

Additionally, the study unveiled a seasonal variation in equine Leishmania spp. infections, with a notable spike during the spring months, aligning with higher average temperatures. This observation underscores the significant influence of climate on the prevalence of leishmaniosis, raising concerns about the potential impact of climate change on the disease's future trajectory.

 

From a One Health perspective, the researchers emphasize the need for a holistic approach to combat leishmaniosis. Given the close contact between horses and humans, horses may act as silent reservoirs, facilitating parasite transmission. As a result, the study advocates for the incorporation of preventive measures for horses, such as regular use of repellents, to control the spread of leishmaniosis across species.

 

For more details, see:

 

Prevalence and Factors Related to Leishmania infantum Infection in Healthy Horses (Equus caballus) from Eastern Spain. 

Martínez-Sáez L, Dulac Q, Montaner-Angoiti E, Marín-García PJ, Llobat L. 

Animals. 2023; 13(18):2889. 

https://doi.org/10.3390/ani13182889

Discussing colic

The latest edition of the Fresh Scoop podcast from Morris Animal Foundation covers colic in
horses. Join Drs. Kelly Diehl and Sharanne Raidal as they discuss the subject, including types of colic, clinical signs, diagnostics, treatments and ongoing research. 

 

For more details, go to:

 

https://www.morrisanimalfoundation.org/article/episode-62-understanding-colic-horses

 

Or, you can download the podcast from all the usual places

Link between feral horses and peatland carbon emissions studied

(c) Constantin Stanciu Dreamstime.com

Feral horse populations in the Australian Alps pose a threat to Sphagnum peatlands, according to recent
research. 

Peatlands serve as highly efficient natural carbon capture and storage ecosystems, surpassing the capabilities of rainforests. Despite covering just 3% of the Earth's land surface, they house approximately 30% of the world's soil carbon—twice the amount stored in all the planet's forests combined.

 

In the Australian Alps, peatlands are characterised by carbon-rich peat soil within mossy wetlands formed from partially decomposed plants in swampy conditions. These ecosystems excel in capturing carbon in live moss layers and storing it in soils for long periods, sometimes spanning thousands of years.

 

However, when peatlands, particularly those rich in Sphagnum moss like those in the Australian Alps, are degraded, they can switch from carbon sinks to carbon sources. The disturbance may release more carbon into the atmosphere as greenhouse gases than they capture.

 

The precise connection between this degradation and the carbon cycling of peatlands remains unclear. A study conducted by researchers from RMIT University in Australia sought to address this knowledge gap. A full report of the work is published in the Journal of Environmental Management.

 

Sarah Treby, and Samantha P. Grover conducted a multi-site comparison of CO2 and methane fluxes from Australian peatlands. The investigation focused on 12 alpine and subalpine Sphagnum moss-dominated bogs in Kosciuszko National Park, New South Wales. Over a seven-day period in March 2022, the researchers sampled seven sites with feral horses present and five without.

 

Using a portable greenhouse gas analyser and transparent chambers to measure peatland carbon dioxide (CO2) emissions, they revealed a correlation between the presence of feral horses and increased carbon loss.

 

Their findings showed significantly higher emissions at sites degraded by feral horses compared to horse-free sites.

 

Sites with horses exhibited carbon emissions to the atmosphere, while sites without horses showed carbon removal from the atmosphere. Notably, net carbon emission was 91% higher in bare soil areas than in Sphagnum-covered areas.

 

Sites with feral horses also displayed higher soil bulk density, temperature, electrical conductivity (EC), and water pH, EC, and turbidity compared to sites without horses. 

 

The findings suggested that excluding feral horses from peatland areas could mitigate carbon loss to the atmosphere and improve overall site condition, peat soil quality, and water quality.

 

 

For more details, see: 

Carbon emissions from Australian Sphagnum peatlands increase with feral horse (Equus caballus) presence

Sarah Treby, Samantha P. Grover

Journal of Environmental Management (2023) Vol 347, 119034

https://doi.org/10.1016/j.jenvman.2023.119034

Benefit of lighting in trailers?

(c) Oleksii Yaremenko Dreamstime.com

 Loading horses into trailers can be challenging and potentially dangerous, especially with young horses. Could lighting in the trailer help make the process less stressful?

Claire Neveux and others investigated how lighting inside a trailer can affect the horse's experience, especially during loading and when the trailer is stationary. They found that having consistent and bright LED lighting inside the trailer can make a difference.

In their study, they used a specially designed trailer with adjustable LED lights. They tested this setup with twenty young trotter horses who were relatively new to travelling and loading. They had them load into the trailer multiple times, (“Loading Phase”). After loading, the horses remained in the stationary trailer for two minutes with the experimenter. (“Stationary phase”).

 

The research team used varying lighting conditions in the trailer, which included different levels of brightness and temperature, such as warm white light (3000K), neutral white light (4500K), and cold white light (6300K) generated by LED lighting. To evaluate how these distinct lighting conditions influenced the horses' reactions, the research team closely monitored the horses' behaviour and documented their heart rates.

 

Among their findings were that horses expressed fewer stress-related behaviours and loaded faster when there was a high light level inside the trailer.

 

In addition, heart rate recovered more quickly when horses were loaded and kept under artificial white light LED lighting in a stationary trailer.

 

However, they stress that many factors, including the horse’s environment, its personality and past experience affect the horses’ response to loading in a trailer. 

 

A full report of the work is published in Applied Animal Behaviour Science.

 

 

For more details, see: 

 

Effects of different LED lighting conditions on young horses during trailer loading and stationary confinement

Claire Neveux, Marion Ferard, Emmanuel Melac, Nicolas Pousset

Applied Animal Behaviour Science (2023) Vol 261, 105885

https://doi.org/10.1016/j.applanim.2023.105885

Careful use of anthelminitcs can help limit resistance

 Recent research suggests that employing selective treatment regimens can significantly reduce the
development of anthelmintic resistance. This is particularly relevant in the context of parasites such as the cyathostomins (small redworms), which are among the most common internal parasites of horses. These parasites have developed resistance to various deworming drugs over the years due to their widespread and indiscriminate use.

In Sweden, a country known for its controlled approach to anthelmintic use, a study was conducted to investigate the presence of resistance to ivermectin, a commonly used deworming medication. The research found no evidence of resistance to ivermectin in cyathostomes in Sweden.

 

ML resistance has been observed in cyathostomins worldwide. However, the current situation in Sweden is unclear. Routine anthelmintic treatment of horses without prior diagnostic tests is rare in Sweden, since anthelmintic drugs were restricted to being available on prescription only in 2007. What effect would this have had on the development of ML resistance in the country?

 

To assess the effectiveness of deworming treatments, two common tests are used: the faecal egg count reduction test (FECRT) and the egg reappearance period (ERP) after treatment. FECRT evaluates whether a dewormer successfully reduces the number of internal parasite eggs in the horse's faeces. Samples are taken before treatment and around 10 to 14 days after deworming, and the two egg counts are compared. A high reduction percentage indicates that the dewormer is effective, while a low reduction percentage suggests potential resistance.

 

As internal parasites develop resistance to dewormers, the egg reappearance period (ERP) shortens, meaning that eggs reappear in the faeces more quickly after treatment.

 

A study led by Ylva Hedberg Alm and her colleagues aimed to assess FECRTs and ERPs following ivermectin (IVM) treatment in Swedish horses. Sixteen equestrian establishments, each with at least six horses excreting a minimum of 150 eggs per gram of faeces (EPG) during screening, were included in the study. FECRTs and ERPs were evaluated in faecal samples before and after IVM treatment (200 µg/kg) and for eight weeks afterward.

 

The questionnaire responses revealed that 69% of establishments administered anthelmintic treatments based on faecal diagnostics. All establishments achieved a high FECRT, exceeding 99.0%, and ERPs ranged from six to over eight weeks. Notably, younger horses were found to excrete cyathostomin eggs earlier after treatment than older horses.

 

The researchers also observed that riding schools, stud farms, and those not segregating summer and winter paddocks had shorter egg reappearance periods.

 

In conclusion, this study in Swedish equestrian facilities employing selective anthelmintic treatment revealed that the establishments maintained longer ERPs and showed no confirmed resistance to ivermectin. These findings support the use of selective deworming strategies as a means of reducing the risk of anthelmintic resistance in horses. The full report is available in Veterinary Parasitology.

 

For more details, see:

 

Retained efficacy of ivermectin against cyathostomins in Swedish horse establishments practicing selective anthelmintic treatment

Ylva Hedberg Alm, Eva Osterman Lind, Frida Martin, Rebecca Lindfors, Nina Roepstorff, Ulf Hedenström, Isabelle Fredriksson, Peter Halvarsson, Eva Tydén

Veterinary Parasitology (2023) Vol 322, 110007

 

https://doi.org/10.1016/j.vetpar.2023.110007

Survey on Behavioural Challenges in Horses

(c) Kseniya Abramova Dreamstime.com

 Is your horse facing behavioural issues? How do you handle these challenges? Whether you're
a horse owner, rider, or work closely with horses, Dr. Orla Doherty would welcome your valuable input.

Dr. Doherty is conducting a research survey to gather insights on how problem behaviours in horses impact riders, handlers, and individuals involved in equine care, as well as the strategies employed to address these issues. Any additional perspectives or knowledge you can provide on this subject will be greatly appreciated. 

A veterinary surgeon, Dr. Doherty graduated from University College Dublin in 1992 and earned a Master's Degree in Animal Behaviour and Welfare from Edinburgh University in 1993. Her commitment to animal welfare led to the establishment of the Animal Behaviour Clinic in Ireland in 1994, where she has been actively addressing behaviour-related concerns in animals across the nation.

 

The survey results will be made publicly available. 

 

To take part, go to:

https://www.surveymonkey.com/r/International_Survey_on_Problem_Behaviours_in_Horses

Grants available for behavioural research

 Morris Animal Foundation has announced a fresh call for research proposals with the goal of enhancing the well-being of horses by advancing our understanding of behavioural health and welfare. The Foundation is particularly keen on projects related to cognition, learning, stereotypies, separation anxiety, horses' affiliative behaviour towards humans, the impact of equine temperament on their welfare, and equine psychopharmacology. Please note that proposals solely focused on behavioural measurements for non-behavioural conditions will not be considered. 

This initiative has been made possible thanks to a generous donation from Dr. Wendy Koch, a veterinarian who has been a steadfast supporter of the Foundation for over three decades. Dr. Koch embarked on her career in animal welfare with the federal government back in 1990 and achieved board certification in animal welfare in 2016. Her deep interest in equine behaviour and welfare research prompted her to champion funding in these important areas.

 

Researchers interested in this opportunity should submit their proposals by 4:59 p.m. ET on December 13, 2023. 

 

For details on how to apply, see the Foundation's Grants page at:

 

https://www.morrisanimalfoundation.org/apply

Breed differences in ACTH concentrations

 Plasma adrenocorticotropic hormone (ACTH) concentration is commonly measured to diagnose pituitary pars intermedia dysfunction (PPID), also known as equine Cushing’s disease. Several intrinsic and extrinsic factors affect ACTH concentrations, including breed. 

Researchers at the University of Melbourne and the University of Queensland, in Australia, conducted a study to prospectively compare plasma ACTH concentrations among different breeds of mature horses and ponies. 

Dr Nicholas Bamford and colleagues aimed to shed light on how plasma adrenocorticotropic hormone concentrations, a crucial indicator for diagnosing pituitary pars intermedia dysfunction in horses, varied across different horse breeds. 

 

The breed groups under scrutiny were Thoroughbred horses, Shetland ponies, and ponies of non-Shetland breeds. 

 

The health of the animals involved was carefully monitored to ensure they showed no signs of illness, lameness, or clinical signs associated with PPID.

 

Blood samples were collected twice a year, around the autumn and spring equinoxes, to capture any seasonal variations. The ACTH levels were measured using a chemiluminescent immunoassay, a common diagnostic tool. 

 

The results revealed that pony breeds, particularly Shetland ponies, exhibited notably higher ACTH concentrations compared to Thoroughbred horses during the autumn season. 

In spring, no differences were identified among the three breed groups.

 

This observation is significant, especially when diagnosing PPID and interpreting ACTH levels accurately.

 

The findings emphasise the importance of considering the specific breed of a horse when interpreting ACTH levels, especially during the autumn months. 

 

Understanding breed-related differences in ACTH concentrations is essential for a more precise assessment of a horse's health and can guide appropriate healthcare and management decisions.

 

For more details, see:

 

Investigation of breed differences in plasma adrenocorticotropic hormone concentrations among healthy horses and ponies

N.J. Bamford, A.J. Stewart, C.M. El-Hage, F.R. Bertin, S.R. Bailey 

The Veterinary Journal (2023) Vol 296–297, 105995

https://doi.org/10.1016/j.tvjl.2023.105995

Discounted Rate for Horses Inside Out Conference 2024

We are excited to announce a special discounted rate for Equine Science Update readers for next year’s Horses Inside Out conference, made possible through a generous offer from Gillian Higgins and the Horses Inside Out team.

You can get 10% off (25% if you purchase before 31st October) with the code: ESU10%

 

The 2024 Horses Inside Out conference, to be held in Loughborough on 17th & 18th February, will revolve around the theme of "Growth and Development", giving insights into horses' life stages, from birth to old age.

 

The conference promises an enriching experience suitable for all. Over the course of two days, attendees will have access to a packed programme of inspiring and educational lectures sharing the latest advancements in equine science.

 

In depth details, reviews and further information can be found here:

https://www.horsesinsideout.com/c24

When booking, remember to input the code (ESU10%) to take advantage of the discounted rate.

 

Call for abstracts for the 2024 ISES conference

(c) Lifeontheside Dreamtime.com

 What constitutes a “Good Life” for a horse and why is it necessary, or indeed possible? How can we ensure every horse enjoys a fulfilling life?

These questions will be the focus of the forthcoming annual conference of the International Society for Equitation Science, scheduled to take place in New Zealand next year.

 

The ISES 2024 Scientific Committee eagerly awaits pertinent contributions and insights that align with the following themes:

• Measuring the impact of Tack and Equipment
• New directions in Training and Riding
• What happens in the ‘Other 23 Hours’ (Outside of Competition and Training)
• Understanding Equine Emotions
• Safe Human-Horse Interactions
• Setting the Horse up for Success (Early experiences, weaning, a second life)
• Sustainable Equine Management and Practice

For more details, see: 

https://www.equitationscience.com/2024-conference

Does bit-chewing promote gut motility?

 Giving horses a bit to chew may provide a simple and inexpensive way of promoting gut motility in horses with ileus, according to a recent study.

Ileus is a disorder where the normal rhythmic contractions that move food and waste through the intestines are disrupted, without an identifiable physical obstruction. It is a potentially life-threatening problem for horses and may be seen especially after abdominal surgery. 

 

Studies in human patients with ileus, have shown that sham feeding, such as giving the patient gum to chew, may improve clinical signs and promote gastrointestinal motility. 

 

Bit chewing, a form of sham feeding adapted for horses, has shown positive effects by reducing gastrointestinal total transit time (TTT). However, previous research has mainly focused on the large intestine; the impact of bit chewing on the small intestine relatively unexplored.

 

In a prospective crossover study, Molly Patton and colleagues compared gastrointestinal motility in horses under both bit-chewing conditions and control conditions (with no bit chewing)

 

Reporting the work in the journal Animals, they write: “Our objective in this study was to investigate whether bit chewing could effectively reduce gastric emptying time (GET), small intestinal transit time (SITT), and total orocecal transit time (OCTT) in clinically normal horses.” 

 

Nine healthy horses participated in the study. The researchers evaluated gastrointestinal motility using a dual approach: employing self-contained videoendoscopy capsules known as ALICAM® and monitoring acetaminophen absorption. ALICAM® capsules, designed for single-use, captured video images stored in their onboard memory as they traversed the digestive tract. These capsules, accompanied by acetaminophen, were introduced into the stomach using a naso-gastric tube.

 

To carry out the study, the horses were randomly divided into two groups: one group with a bit and the other without a bit. This allocation was reversed a month later, ensuring each horse served as its own control.

 

Acetaminophen serum samples were used as a marker to gauge gastric emptying time (GET). Additionally, ALICAM capsules helped in determining not only GET but also small intestinal transit time (SITT) and overall orocecal transit time (OCTT).

 

The research findings indicate a significant reduction in orocecal transit time following bit chewing, without any observed adverse effects.

 

“The findings from our study not only revealed no adverse effects associated with bit chewing but also demonstrated a significant reduction in OCTT following this activity.”

 

They conclude: “This suggests that bit chewing could provide a safe, cost-effective, and efficient treatment to enhance small intestinal motility in horses. These results hold promising implications for improving the management and treatment of ileus in equine patients, potentially leading to better outcomes and enhanced overall well-being for these animals.”

 

For more details, see:

 

"Effects of Bit Chewing on Gastric Emptying, Small Intestinal Transit, and Orocecal Transit Times in Clinically Normal Horses" 

Molly E. Patton, Frank M. Andrews, Sophie H. Bogers, David Wong, Harold C. McKenzie, III, Stephen R. Werre, and Christopher R. Byron. 

Animals (2023) 13, no. 15: 2518. 

https://doi.org/10.3390/ani13152518

Herd dynamics in a multilevel society of Przewalski’s horses

Photo: Katalin Ozagány

 A team of researchers from the Hungarian Research Network (HUN-REN), the University of Debrecen
(UD), Eötvös Loránd University (ELTE), and the Hortobágy National Park Directorate studied the social system of the Przewalski's horse herd in Hortobágy. The research involved a combination of drone-based movement analysis and long-term population monitoring data.

The researchers used drones to monitor the 278 Przewalski's horses, individually identifying most of them, and found that these wild horses, like humans, live in a complex, multilevel society. They used high-resolution aerial videos to understand the structure of this society and its past and future group changes.

 

The research is published in the scientific journal Nature Communications.

 

Studying the social behaviour of a large group of animals using traditional methods is time-consuming. Nevertheless, this study shows that collecting high-resolution data, even just a few minutes of animal movement footage, can yield sufficient information to understand the population's social structure and make predictions about its past and future dynamics.

 

"We wanted to investigate the group movements of the Przewalski’s horse herd in Hortobágy, Hungary. However, observing nearly 300 horses at the same time is not an easy task," says Katalin Ozogány, the first author of the study, member of the HUN-REN–UD Behavioural Ecology Research Group of the Hungarian Research Network and the University of Debrecen (Hungary). 

 

"We took aerial videos of the herd using drones while they were moving around the reserve, and based on the footage, we determined the movement routes of all the individuals of the herd with high spatio-temporal resolution."

 

They used two drones to record the herd’s movements.  One recorded a wide-angle view to track the movement of all individuals in the herd. A second drone scanned through the herd providing close-up views to allow identification of individual animals.

 

In the past, wild horses ranged across the vast expanses of the Eurasian steppes, but today, they are confined to just a few national parks. The Przewalski's horse, classified as endangered, represents the sole surviving sub-species, with a worldwide population numbering less than 3,000 individuals. 

 

Przewalski’s horses have been living in Hortobágy since 1997, in the Pentezug reserve. In the first years after founding the population, the harems (each consisting of a stallion and a group of breeding mares) lived in their own home ranges and rarely interacted with each other. Now, for over a decade, the harems have grouped together to form a large herd, in which harems can still be distinguished, but they move together in the reserve. 

 

Such a multilevel social structure, characteristic of humans, is uncommon in animals. It is mainly found in primates, but also occurs in cetaceans, elephants, and some ungulates. 

 

Analysis of the herd’s movements yielded surprising results. "The individuals of the group coordinate their movements and align with each other, and by detecting these fine interactions between the individuals, it turned out that we can assess the herd's social network based on the group movements," explains lead author Máté Nagy, head of the Collective Behaviour 'Lendület' Research Group of the Hungarian Academy of Sciences and Eötvös Loránd University (Hungary).

 

The researchers combined the short-term movement observations of a few minutes with long-term population data going back two decades. allowing them to reconstruct the development of the harem groups over more than 20 years. 

 

Since the establishment of the reserve, the wild horses have been individually recognized by the park staff who regularly collected data on population changes. "Thanks to population monitoring, we know the parentage of the animals, which we also confirm with genetic sampling, as well as their place in the social system, that is, we regularly record which individual belongs to which harem," says co-author Viola Kerekes, project leader of the Hortobágy National Park Directorate.

 

The analyses showed that the social relations of wild horses are related to kinship and familiarity of the animals. For example, mares are closer to each other in the social network if they have been harem mates for a longer time. Kinship may play a significant role in the organization of harems into herds since harems of sibling stallions are closer to each other in the social network than harems of unrelated stallions. Between the closer harems, at the same time, the dispersal of mares was greater, which also contributes to the relations between harems through familiarity.

 

"It is an exceptional opportunity to explore the social network of an entire population and its dynamics," explains co-author Attila Fülöp, a researcher at the Babeş-Bolyai University (Romania) and the HUN-REN–UD Behavioural Ecology Research Group. It turned out that older and larger harems, which typically belong to older and more experienced stallions, occupy more central locations in the herd’s social network. A possible explanation is that harem stallions form an alliance to protect their harems more effectively against the bachelor males. Harems moved as cohesive units within the herd, while bachelor males were typically found on the outer margins of the herd.

 

"One of the surprising outcomes of the study is that we can infer future group dynamics by observing current movement," adds Zoltán Barta, lead author, head of the Department of Evolutionary Zoology of the University of Debrecen and the HUN-REN–UD Behavioural Ecology Research Group. The researchers showed that mares that lived in different harems at the time of the aerial observations but became harem mates within two years after the observations, were already moving in more similar routes than the other mares. So, through the movement analysis, it was also possible to conclude which mares will leave their harem in the next two years and which harem they will transfer to.

 

"Not only did we learn new, previously unknown details about the social life of Przewalski's horses, but we highlighted that drone observations, which can be applied even in wild populations, can provide very detailed information."

 

For more details, see:

 

Fine-scale collective movements reveal present, past and future dynamics of a multilevel society in Przewalski’s horses

Katalin Ozogány, Viola Kerekes, Attila Fülöp, Zoltán Barta & Máté Nagy 

Nature Communications (2023) vol 14, Article number: 5096 (2023) 

https://doi.org/10.1038/s41467-023-40523-3

 

https://www.youtube.com/watch?v=H2BhFjEbZDE