New virus found in Swiss horses

© Viacheslav Nemyrivskyi Dreamstime.com

  

Swiss researchers have identified a novel virus in the brains of four horses that were
euthanased after developing neurological disease, prompting investigations into whether the virus may represent an emerging cause of equine central nervous system (CNS) disease.

Since late July 2026, equine referral hospitals at the Universities of Bern and Zurich have seen an increase in horses presenting with neurological signs including ataxia, muscle fasciculations, hypersensitivity and lethargy. Extensive diagnostic investigations failed to identify recognised infectious causes of neurological disease in many of these cases.

Researchers at the Swiss Institute of Virology and Immunology (IVI), working with the Vetsuisse Faculty at the University of Bern, subsequently detected genetic material from a Shamonda-like virus, an Orthobunyavirus in the Simbu serogroup, in brain tissue collected from four affected horses following post-mortem examination. Three cases originated from Zurich and one from Bern. This is the first reported detection of a Simbu serogroup Orthobunyavirus in horses in Europe.

The virus has been confirmed in post-mortem brain tissue from four horses with neurological disease. It has not yet been found in blood or cerebrospinal fluid from affected live horses, so ante-mortem diagnosis is currently not possible. Antibody testing can show previous exposure, but cannot confirm that the virus caused the neurological disease. There is currently no specific treatment, and affected horses receive supportive care.

Like other members of the Simbu serogroup, the virus is believed to be transmitted by Culicoides biting midges. Related viruses, including Schmallenberg virus, are well recognised in European livestock.

At present, there is no evidence that the Shamonda-like virus causes neurological disease in horses. Although its detection in affected brain tissue makes it a plausible candidate, researchers have not established a causal relationship. Further studies are needed to determine whether the virus is responsible for the recent increase in neurological cases in Switzerland or whether its presence is incidental.

Veterinarians investigating horses with neurological signs should therefore continue to consider established differential diagnoses, including equine herpesvirus (EHV), West Nile virus (WNV) and tick-borne encephalitis, while research into the Shamonda-like virus continues.

The UK's Equine Infectious Disease Surveillance (EIDS), based at the University of Cambridge, reports that there is currently no evidence of Shamonda-like virus-associated disease in horses in the UK. However, because infected Culicoides midges may be transported long distances by wind, and horses continue to move between mainland Europe and the UK, the situation is being monitored closely. 

 

For more details, see:

https://www.ivi.admin.ch/en/neues-orthobunyavirus-der-simbu-serogruppe-bei-rindern-entdeckte

Seasonal and breed differences in resting ACTH

Pituitary pars intermedia dysfunction (PPID), commonly referred to as equine Cushing’s
disease, is a common endocrine disorder primarily affecting older equids. Current estimates suggest that approximately 25% of horses and ponies aged 15 years and older may be affected.

The condition arises from degeneration of dopaminergic neurons within the hypothalamus, leading to loss of regulatory control over the pars intermedia region of the pituitary gland. As a result, excessive production of several hormones, including adrenocorticotropic hormone (ACTH), occurs. Although PPID is progressive and currently incurable, early diagnosis and appropriate management can significantly slow disease progression and improve equine welfare.

Clinical signs of PPID are variable and may develop gradually. Common indicators include hypertrichosis (abnormal or excessive hair growth), delayed or incomplete shedding of the winter coat, lethargy, weight loss, and metabolic disturbances. One of the most serious associated complications is laminitis, which can severely compromise quality of life and may become life-threatening. Due to the variable presentation of clinical signs, diagnostic testing is frequently required to support clinical suspicion.

Measurement of baseline plasma ACTH concentration is widely used as a primary diagnostic tool for PPID. However, interpretation of ACTH values is complex, as concentrations are influenced by several factors, particularly seasonal variation. In the Northern Hemisphere, resting ACTH levels typically rise during late summer and early autumn, approximately between August and October. Understanding these physiological fluctuations is essential to avoid misinterpretation of results and potential overdiagnosis.

Breed-related differences in ACTH concentrations have also been documented. An Australian study identified that pony breeds, particularly Shetland ponies, displayed significantly higher ACTH concentrations during autumn when compared with Thoroughbred horses. These findings suggest that species, breed type, and possibly body size may influence endocrine responses and should be considered during diagnostic evaluation.

Further research has expanded understanding of ACTH variation across different equid species. A study conducted by Goodrich and colleagues, involving researchers from Cornell University, the University of California, Davis, and private veterinary practice, investigated baseline ACTH concentrations in donkeys and horse–donkey hybrids across several regions of the United States. The study aimed to provide a more comprehensive understanding of seasonal ACTH variation in healthy equids, as previous research had been limited by small sample sizes and restricted geographic representation.

The study evaluated 19 standard donkeys, 14 miniature donkeys, and 28 hybrids, with animals located in California, Massachusetts, New York, and Texas. Blood samples were collected twice monthly from June to November 2019 and monthly from December 2019 to May 2020. Results demonstrated a clear seasonal rise in ACTH concentrations across all groups, with levels increasing from mid-August and peaking in late September. Mean ACTH concentrations during peak periods reached approximately 109.6 pg/mL in standard donkeys, 134.6 pg/mL in miniature donkeys, and 100.8 pg/mL in hybrids.

Notably, hybrids consistently exhibited lower ACTH concentrations compared to donkeys throughout the year. During the seasonal peak, ACTH levels in hybrids were 23% lower than in standard donkeys and 51% lower than in miniature donkeys. Similar differences persisted during non-peak periods, with hybrids showing reductions of approximately 30% compared to both donkey groups. These findings highlight important species-related differences that may influence diagnostic interpretation.

Overall, research demonstrates that accurate diagnosis of PPID requires careful consideration of seasonal variation, species differences, and breed predisposition alongside clinical assessment. Improved understanding of normal ACTH fluctuations in healthy equids enhances diagnostic accuracy and supports more effective management of this common and welfare-significant endocrine disorder.

 

For more details, see:

Goodrich, Erin L., Sebastián Gonzalo Llanos-Soto, Renata Ivanek, Toby Pinn-Woodcock, Elisha Frye, Amy Wells, Stephen R. Purdy, Emily Berryhill, and Ned J. Place.

Both Season and Equid Type Affect Endogenous Adrenocorticotropic Hormone Concentrations in Healthy Donkeys, Mules and Hinnies in the United States

 Animals (2026) 16, no. 2: 290.

https://doi.org/10.3390/ani160202902

Intra-articular corticosteroids and laminitis risk: new insights into metabolic effects of methylprednisolone acetate

(c) Virgonira Dreamstime.com

Intra-articular corticosteroid injections are widely used in equine practice for the management of
joint pain and lameness. Despite their clinical benefits, concerns persist regarding the potential for corticosteroid-induced laminitis, particularly following reports of laminitis developing after joint injections. While many joints are injected safely every year, adverse metabolic consequences appear to be relatively uncommon, raising questions about whether specific corticosteroid formulations, dosages, or patient factors influence risk.

One proposed mechanism for corticosteroid-associated laminitis involves systemic metabolic effects following intra-articular administration. Corticosteroids are known to interact with the hypothalamic-pituitary-adrenal (HPA) axis and may interfere with glucose and insulin metabolism. Disruption of these pathways, particularly the development of hyperinsulinemia, is strongly associated with laminitis. However, not all corticosteroids appear to exert identical metabolic effects, and differences between formulations may be clinically relevant.

To address these concerns, Allen E. Page and colleagues conducted a controlled study at the Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky. The objective of the study was to examine the metabolic effects of intra-articular methylprednisolone acetate (MPA) when administered into multiple low-motion joints.

The study population consisted of six 3-year-old mixed-breed geldings from the university’s research herd. All horses were screened approximately five weeks before the investigation and were confirmed to be free of pituitary pars intermedia dysfunction (PPID) and insulin dysregulation. This ensured that any observed metabolic effects could be attributed to treatment rather than pre-existing endocrine disease.

Each horse was randomly assigned to receive either intra-articular MPA or an equivalent volume of saline. MPA was administered bilaterally into the distal intertarsal and tarsometatarsal joints, with a dose of 20 mg per joint for a total of 80 mg. Serial blood samples were collected to measure resting adrenocorticotropic hormone (ACTH), cortisol, insulin, and glucose concentrations. In addition, repeated low-dose oral sugar tests were performed to assess post-challenge insulin and glucose responses. After a six-week washout period, treatments were crossed over and the protocol was repeated.

The results demonstrated that intra-articular treatment with a total dose of 80 mg of MPA caused significant suppression of the HPA axis. Specifically, resting ACTH and cortisol concentrations were significantly decreased between four and twelve hours following MPA injection. This finding confirms that even intra-articular administration of corticosteroids can produce measurable systemic endocrine effects.

Importantly, however, no significant changes were observed in resting insulin or glucose concentrations. Furthermore, insulin and glucose responses to oral sugar testing at 2, 7, and 14 days post-treatment were not affected by MPA administration. These findings contrast with previous reports involving other intra-articular corticosteroids, which have demonstrated post-injection hyperinsulinemia.

The authors conclude that, in metabolically normal horses, an intra-articular dose of 80 mg of MPA does not appear to induce clinically significant disturbances in insulin or glucose regulation. This observation may help explain the reported practitioner sentiment that MPA carries a lower risk for corticosteroid-induced laminitis compared with other formulations.

Nevertheless, the study’s findings should be interpreted cautiously. The horses involved were young, healthy, and free of known endocrine disease. Additional research is needed to determine whether similar results would be observed in insulin-dysregulated or laminitis-prone horses. Until such data are available, intra-articular MPA should not be assumed to be universally safe in higher-risk populations, despite its apparently favourable metabolic profile in healthy individuals.

  

For more details, see:

Page, A. E., McPeek, J. L., Carattini, S., McGreevy, E., & Adam, E. (2025). 

Intra-articular methylprednisolone acetate does not induce hyperinsulinemia or hyperglycemia in metabolically normal horses. 

Journal of the American Veterinary Medical Association (2025). 

 https://doi.org/10.2460/javma.25.08.0566

New device aims to help asthmatic horses breathe more easily

The new equine respirator (Tim Brouk)

A novel collaboration between Purdue University’s College of Health and Human Sciences and the College of Veterinary Medicine may offer significant relief for horses suffering from asthma—a common respiratory condition often triggered by inhaled particles such as mould spores found in dusty hay.

Equine asthma, like its human counterpart, is frequently linked to allergic sensitisation to airborne irritants. While a range of treatment and management options exist, the most effective strategy remains straightforward: minimise exposure to the particles that trigger the condition. This is typically attempted by soaking or steam-treating hay to reduce airborne dust. However, researchers at Purdue have taken this one step further by developing a wearable device that could filter out harmful particles before they even reach the horse’s airways.

At the heart of this innovation is an equine respirator—a specially designed breathing mask that attaches directly to a horse’s bridle or head collar. The device allows the horse to breathe filtered air through an intake positioned over the bridge of the nose, while exhalation occurs through valves located near the nostrils. Crucially, the design allows horses to eat and drink while wearing the respirator, making it suitable for continuous use in dusty environments like stables or arenas.

The project was born out of a cross-disciplinary partnership. Dr. Jae Hong Park, associate professor of Health Sciences, had been working on developing human respirators, especially for welders working in manufacturing facilities. His research caught the attention of Dr. Laurent Couëtil, a professor of Large Animal Internal Medicine in the College of Veterinary Medicine, who wondered if a similar approach could be adapted for equine use.

Momentum built when Chang Geun Lee, a Ph.D. candidate in Health Sciences with a background in mechanical engineering and industrial design, joined Park’s lab. Lee brought a unique combination of technical skills and practical design experience that proved instrumental in creating a functional and comfortable respirator for horses.

The team, which also includes Laura Murray, RVT and research technologist in the Department of Veterinary Clinical Sciences, spent months designing, prototyping, and refining the respirator. Their efforts have culminated in a practical tool that could significantly improve the quality of life for horses affected by respiratory issues—particularly those regularly exposed to dusty environments.

By combining expertise in health sciences, veterinary medicine, and engineering, this collaboration exemplifies the power of interdisciplinary research to solve real-world problems—and could mark a significant advance in the management of equine asthma.

The research team are now looking to see if the device could be made available for general use.

For more details, see: 

https://vet.purdue.edu/news/asthmatic-horses-can-breathe-easier-thanks-to-purdue-health-and-human-sciences-and-college-of-veterinary-medicine.php

Progress towards understanding the cause of Equine Grass Sickness

Pony with chronic grass sickness (McGorum et al)

 An international team of researchers has identified what they believe to be the probable cause of equine grass
sickness (EGS). Their findings suggest that a neurotoxin, similar in action to snake venom toxins but produced by pasture microbes, is the likely culprit. The work is set to be published in the Equine Veterinary Journal (EVJ) and is currently freely available online. A special editorial in the January 2025 issue of EVJ, authored by Bruce McGorum and colleagues, highlights the study’s findings and their implications. 

This breakthrough has the potential to pave the way for novel treatments and improved diagnostics for this devastating disease.

 

Equine grass sickness (EGS), also known as equine dysautonomia, is a major cause of mortality in horses and ponies in Great Britain, with more than 80% of cases proving fatal. First recognised in Scotland over 100 years ago, EGS remains most prevalent in Great Britain but has been reported in several northern European countries, South America, and very infrequently in North America.

 

EGS damages the autonomic nervous system, which controls involuntary bodily functions, with particularly severe effects on the gastrointestinal tract. Clinical signs range from depression, difficulty eating and swallowing, and weight loss to gastric reflux, abdominal pain, and death. The disease causes rapid degeneration of nerves, leading to paralysis of the gastrointestinal tract and other systemic effects such as muscle weakness, drooping eyelids, excessive salivation, sweating, and muscle tremors.

 

As there is currently no effective treatment for the most severe (acute and sub-acute) forms of the disease, horses are euthanised on humane grounds, typically within 24-48 hours of showing abnormal signs. In contrast, up to 50% of horses with the mild (chronic) form of grass sickness may survive with intensive nursing and supportive care.

Researchers from the Dick Vet Equine Hospital (RDSVS University of Edinburgh), Newcastle University, Istituto Zooprofilattico Sperimentale delle Venezie, and the University of Padova have made significant strides in identifying the neurotoxin responsible for EGS. Using electron microscopy, they examined post-mortem samples from horses with EGS and compared them to control samples. Their findings revealed that 72.2% of neuromuscular junctions (NMJs) in EGS-affected horses displayed abnormal morphology, compared to just 6.9% in controls.

 

These abnormalities are believed to represent a toxin-specific signature for a neurotoxic enzyme known as phospholipase A2. This enzyme disrupts the microscopic sites of communication between nerves and muscles (NMJs), which are crucial for normal muscle function.

 

Ongoing work aims to definitively identify the source of this toxin. Researchers suspect it is produced by a microbe, such as a bacterium or fungus, that thrives on pasture during the cold and dry weather conditions that typically precede outbreaks of EGS.

 

Interestingly, neurotoxic phospholipase A2 enzymes are also found in the venom of many poisonous snakes. While venomous snakes are not implicated in EGS, researchers hope that drugs being developed to treat nerve damage in snakebite victims could help promote nerve regeneration and recovery in horses with grass sickness.

 

Professor Bruce McGorum, R(D)SVS said: “Identifying a probable cause of Equine Grass Sickness represents a significant breakthrough. We hope that this discovery will lead to novel treatments and improved diagnostics for this devastating condition. We are very grateful for the generous support we have received from horse owners, veterinary surgeons, scientists, charities and funding bodies.” 

 

“Further work is underway to determine the source of this neurotoxin; it is likely to be produced by a microbe such as a bacterium or fungus which grows on the horse’s pasture during the cold and dry weather which precedes the disease.” 

 

This discovery represents a significant step forward in understanding equine grass sickness. By pinpointing the probable cause, researchers can now focus on developing effective treatments and preventive strategies. Advances in identifying the toxin’s source and exploring therapeutic interventions for nerve regeneration offer hope for reducing the impact of this devastating disease.

 

For more details, see:

 

McGorum, B., Pirie, R.S., Bano, L., Davey, T., Harris, J. and Montecucco, C. (2025), 

Neurotoxic phospholipase A₂: A proposed cause of equine grass sickness and other animal dysautonomias (multiple system neuropathies). 

Equine Vet J, 57: 11-18.

https://doi.org/10.1111/evj.14442

 

McGorum BC, Davey T, Dosi MCM, Keen JA, Morrison LR, Pirie RS, Shaw DJ, Harris JB.  

Equine grass sickness is associated with major abnormalities in the ultrastructure of skeletal neuromuscular junctions. 

Equine Vet J.  2025; 57(1): 193–202.

https://doi.org/10.1111/evj.14063

The role of equine practice in the downfall of antibiotics

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 Less than a century ago, Alexander Fleming observed that a mould, Penicillium notatum, inhibited the growth of Staphylococcus bacteria on a petri dish. This discovery paved the way for the development of antibiotics, which
revolutionised medicine in the 20th century.

However, the overuse and misuse of antibiotics have led to a growing problem: antimicrobial resistance (AMR). The "golden age" of antibiotics appears to be waning. In the same way that anthelmintic resistance has become a significant challenge in managing parasites in horses, AMR is now a pressing global issue.

 

The World Health Organization (WHO) has classified AMR as a widespread and serious threat, warning that it "is no longer a prediction for the future; it is happening right now in every region of the world and has the potential to affect anyone, of any age, in any country." While anthelmintic resistance is widely discussed, it is no surprise that bacteria, which reproduce far more rapidly than gastrointestinal parasites, are also developing resistance to substances designed to eliminate them.

 

In 2016, the Review on Antimicrobial Resistance, commissioned by the UK government and chaired by economist Jim O'Neill, predicted that, if current trends continue, antimicrobial resistance  could lead to 10 million deaths annually by 2050, surpassing deaths caused by cancer and other major diseases.

 

Despite that, public interest in the threat of the downfall of antibiotics appears limited, suggests Bruce Bladon, guest editor of the latest virtual issue of the Equine Veterinary Journal (EVJ).  He has chosen 15 of the most pertinent articles on the topic from EVJ and its sister journal, Equine Veterinary Education. His intention is to highlight the significant risk resistance poses and the need to monitor and change equine practice protocols. The virtual collection is free to view here (until 20 January 2025)

 

Three articles: Antimicrobial use and antimicrobial resistance in horses, Antimicrobial resistance in horses, a call to actionand Room for improvement? The use of antimicrobials in equine respiratory disease present the background on current legislation, use and monitoring of antimicrobials in equine practice.

 

Audit of antimicrobial use in eleven equine practices over a five-year period (2014–2018) showed an impressive reduction in antibiotic usage but failed to accommodate the fact that the corporatised practices in the study may have been treating less horses. In addition, the withdrawal of a key antimicrobial from sale during the period had reduced antimicrobial usage figures.

 

Antimicrobial prescribing practice in UK equine veterinary practice and Antimicrobial prescribing and antimicrobial resistance surveillance in equine practice established that potentiated sulphonamides were the most frequently used class of antibiotic in equine practice and that there was a positive adoption of written antimicrobial usage policies. However, both also confirmed that the use of Highest Priority Critically Important Antimicrobials was frequent.

 

Use of antimicrobials licensed for systemic administration in UK equine practice reported the incidence of antibiotic prescription, to 19.5% (95% CI: 19.2%–19.8%) of 322 equids attended by UK veterinary practices in 2018. Category B antimicrobials were prescribed to 1228 equids (1.9%, 95% CI: 1.8%–2.0%). Active racehorses were 1.6 times more likely to receive antibiotics than non-racehorses. 

 

Antibiotic use in first opinion equine practice in the United Kingdom: Serial point prevalence surveys in 17 practicesShowed that Highest Priority Critically Important Antibiotic usage was similar, at 1.6% of consultations, with potentiated sulphonamides and oxytetracycline constituting two thirds of antibiotic prescriptions. 

 

Antibiotic usage in 14 equine practices over a 10-year period (2012–2021) produced volumetric data compatible with the ESVAC and VARSS methodology. It showed that antibiotic usage did decline during the study period, from 60 to 46 mg/kg. A second metric, the Defined Daily Dose Veterinary per year was also reported, which was 1.52 in 2021, down from 1.7 in 2012. 

 

Changing policy to treat foals with Rhodococcus equi pneumonia in the later course of disease decreases antimicrobial usage without increasing mortality rate reported on the treatment only of foals with larger abscesses. The authors documented a reduction in treatment of foals with rhodococcus pneumonia from 82% to 51% and reduction of median course duration from 41 to 23 days, associated with a statistically insignificant increase in all causes of mortality from 1.15% to 1.65%.

 

Standing equine cheek tooth extraction: A multivariate analysis of the effect of antibiotics on the risk of post-operative complications reported there was minimal difference in complication rates associated with antibiotic treatment versus extraction

performed without perioperative antimicrobial prophylaxis.

 

Surgical antimicrobial prophylaxis: Current standards of care reported on the extensive evidence-based guidelines in human surgery, which have been adapted to equine usage. 

 

Post operative synovial sepsis following endoscopic surgery: Increased risk associated with the carpal sheath showed an identical rate of post-operative sepsis following arthroscopy without surgical antimicrobial prophylaxis compared to surgical antimicrobial prophylaxis.

 

Incidence and risk factors for complications associated with equine general anaesthesia for elective magnetic resonance imaging and Antimicrobial prophylaxis is not indicated for horses undergoing general anaesthesia for elective orthopaedic MRI provided contrasting results. This made it difficult to draw a conclusion about the need for peri-anaesthetic antimicrobials.

 

“Ultimately, the issue is reducing antimicrobial resistance, particularly in the human healthcare field,” said Bruce Bladon. “It is acknowledged that surgeon behaviour is a limiting factor in the adoption of appropriate surgical antimicrobial prophylaxis policies. Maybe if a clinician was persuaded that avoiding antibiotic prescription would reduce the incidence of antibiotic resistance, they might be more inclined to withhold prophylactic treatment.

 

“There is a need for a national surveillance programme. If you cannot measure it, you cannot manage it.” 

 

The virtual issue can be found at https://beva.onlinelibrary.wiley.com/doi/toc/10.1001/(ISSN)2042-3306.antibiotics

 and will be free to view until 20 January 2025.

Testing for insulin dysregulation after transportation could lead to a false positive result

(c) Anna Cvetkova Dreamstime.com

Recent research indicates that conducting tests to identify insulin dysregulation (ID) in horses after transportation may lead to false positive results.

The oral sugar test (OST) is commonly used to assess insulin dysregulation, a key component of equine metabolic syndrome (EMS). This test involves taking blood samples at specific intervals before and after administering a dose of sugar, typically in the form of corn syrup. By analysing blood glucose and insulin levels, the OST evaluates how the horse’s body processes a sudden intake of sugar.

 

As this is a time-consuming test, it is often more practical to perform it in a clinic setting. However, recent findings have shown that transportation may influence test outcomes, potentially leading to false positives—where a horse with normal insulin function appears to have ID.

 

Dr. Erica Jacquay and Dr. Amanda Adams from the University of Kentucky, in collaboration with the WALTHAM™ Equine Studies Group, conducted a study to examine the effects of short-term transportation on stress parameters and insulin responses to the OST in horses both with and without ID. The research was recently published in the Equine Veterinary Journal.

 

The study involved seven non-pregnant ID mares and seven non-pregnant non-ID mares, all experienced with transportation. The horses were transported in groups for approximately 1.5 hours to and from their home base by the same driver. An OST (0.15 mL/kg body weight Karo Light Corn Syrup) was conducted 24 hours before and 3 hours after the journey.

 

The findings revealed that both serum and salivary cortisol levels significantly increased due to transportation, with no differences observed between ID and non-ID horses. As expected, the ID mares showed higher insulin responses to the OST on both occasions. 

 

However, in 5 out of 7 non-ID mares, post-travel OST insulin levels surpassed the diagnostic threshold for ID, suggesting that these horses could have been mistakenly diagnosed with insulin dysregulation. Additionally, some ID mares showed post-travel T60 OST insulin levels that were more than double their pre-transportation levels.

 

These results imply that real-world testing conditions, including transportation, may lead to misdiagnoses of insulin dysregulation and inappropriate classification of horses as having EMS.

 

“This research is an important step in improving our understanding of insulin dysregulation and EMS,” said Dr Pat Harris, head of the WALTHAM™ Equine Studies Group which provides the science behind the SPILLERS brand. “The findings show that performing an OST three hours after short-term transportation may result in inaccurate ID status, whether testing a new case or monitoring the status of an ID horse. In addition, special care should be given when transporting horses with ID especially those with a history of hyperinsulinaemia- associated laminitis.

 

“Further studies are needed to determine the best timing of diagnostic testing if transporting horses to a veterinary clinic for OSTs.”

 

For more details, see:

 

Jacquay ET, Harris PA, Adams AA. T

he impact of short-term transportation stress on insulin and oral sugar responses in insulin dysregulated and non-insulin dysregulated horses. 

Equine Vet J. 2024.

https://doi.org/10.1111/evj.14403

Warning of possible adverse effects of SGLT2i on horses.

© Brian Sedgbeer Dreamstime.com

A group of veterinary experts have issued a warning regarding the potential adverse effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in horses. In a letter published in the Veterinary Record, Bruce McGorum and clinicians from leading veterinary hospitals like the Royal (Dick) School of Veterinary Studies, Edinburgh, Rossdales Equine Hospital, the University of Liverpool, and the Royal Veterinary College expressed their concerns.

These medications, such as ertugliflozin and canagliflozin, are increasingly used to treat equine metabolic syndrome (EMS), particularly in horses with laminitis that hasn't responded to dietary adjustments. While these drugs have shown promise in reducing serum insulin concentrations, promoting weight loss, and managing laminitis related to hyperinsulinemia, concerns have been raised about significant adverse effects.

 

Minor side effects reported include increased serum triglycerides and liver enzymes, dullness, and increased drinking and urination. However, more serious cases have shown markedly elevated serum triglycerides (above 40 mmol/L), increased liver enzymes (such as GGT, GLDH, LDH), and bile acids, indicating potential liver damage or dysfunction. These biochemical changes were also accompanied by clinical signs such as dullness, loss of appetite, gastric impaction, bilateral laryngeal paralysis, hepatic encephalopathy, and, in some cases, death.

 

Due to these risks, the experts recommend that SGLT2 inhibitors be used only in horses that have not responded to adequate dietary or exercise management, or those with severe laminitis. 

 

Additionally, they advise against using these medications in horses with pre-existing liver disease or hyperlipaemia and emphasize the importance of regular monitoring of diet, liver enzymes, serum triglycerides, and bile acids. Horse owners should be educated about the signs of hyperlipaemia and the potential risks involved in the use of these drugs.

 

Further research is needed to fully understand the risk factors and adverse effects of SGLT2 inhibitors in horses. Until then, their use should be restricted to cases where other treatment options have failed.

For more details, see:

B C McGorum, J A Keen, S McCullagh, CM Marr, C MacKenzie, H Carslake, N Menzies-Gow, Bettina Dunkel, M Hewetson, J Reed, E Knowles.

Potential adverse effects of SGLT2i in horses 

Veterinary Record (2024) vol 195, 253

Seasonal sycamore risk

 The British Equine Veterinary Association (BEVA) is reminding horse owners to keep horses away from sycamore trees as their seeds can cause fatal illness, known as atypical myopathy. 

Seeds (masts or helicopters) from the common sycamore tree (Acer pseudoplatanus) produce a toxin called Hypoglycin A, which can remain present in high concentrations in seedlings. When horses eat these, either by accident or because they are lacking other forage options, some individuals will develop severe and often fatal muscle damage, called atypical myopathy. 

 

Symptoms include muscle soreness, weakness, breathing issues, and dark urine. Immediate veterinary care is crucial, as 75% of affected horses die.

 

“With leaves still on trees now is the time to identify sycamores in the vicinity of your horse’s fields and predict the future risk,” said Lucy Grieve, Veterinary Projects Officer at BEVA “Once the leaves start to turn and then drop it will be much more difficult to spot sycamores.”

 

To prevent atypical myopathy, she advises:

 

·      Identify sycamore trees near fields and anticipate risk before leaves fall.

·      Collect seeds or exclude horses from affected areas using electric fencing or stabling. 

·      provide supplementary forage to prevent seed ingestion.

·      Don’t fell seed-laden trees, as it may worsen contamination.

·      Monitor horses carefully even after they have been moved from affected pasture as disease can occur up to four days after exposure.

 

For further information you can download the Royal Veterinary College’s fact sheet on  Atypical Myopathy: https://www.rvc.ac.uk/Media/Default/Comparative%20Neuromuscular%20Diseases%20Laboratory/Atypical%20Myopathy%20fact%20file%20updated%202022.pdf

 

For further information visit www.beva.org.uk.

Is faecal microbiota transplantation useful for treating diarrhoea in foals?

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 Diarrhoea is a common problem in foals under 6 months of age. 

There are many causes, or combination of causes, including infectious, managerial, and environmental factors.  

Foal diarrhoea can lead to dehydration, electrolyte imbalances, and, in severe cases, systemic infections. In such cases, it can become life-threatening.

 

Diarrhoea and Systemic Inflammatory Response Syndrome (SIRS) in foals are interconnected conditions that demand immediate attention. While diarrhoea is a frequent occurrence, it can escalate to SIRS, particularly when associated with severe infections or when significant dehydration and systemic stress occur.

 

A common contributor to diarrhoea in foals is dysbiosis, or a disruption in the normal intestinal microbiota. Could restoring this microbial balance be a potential solution for managing this potentially fatal condition? 

 

Faecal microbiota transplantation (FMT) has been used in adult horses to reduce diarrhoea and improve alpha diversity, a measure of the variety of microbial species within an individual’s gut.

 

A recent study in Australia, published in the Journal of Veterinary Internal Medicine, explored the effects of FMT in foals with diarrhoea and SIRS. The study, led by Jillian Bell, involved clinicians from three equine veterinary hospitals. It included 25 foals under six months of age with diarrhoea and SIRS who were admitted for treatment.

 

In the randomised, placebo-controlled cohort study, 19 foals were enrolled in the FMT group, while 9 were in the control group. The treatment groups received either FMT or an electrolyte solution once daily for three days. Researchers collected faecal samples from the foals on days 0 (D0), D1, D2, D3, and D7 to monitor changes.

 

The FMT solution was prepared 15 minutes prior to treatment. from fresh manure collected from healthy donor horses (previously screened for pathogenic agents). About 300 g of manure was blended with 1 L of warm chlorinated water (95°F) for 30 to 60 seconds, then strained through a wire strainer or gauze into a clean container.

 

The study found that FMT was associated with improvements in some clinical signs and certain clinicopathological parameters. FMT had no significant impact on survival rates (P = 0.3) or the resolution of diarrhoea (P = 0.4). Foals receiving FMT, however, showed a significantly lower heart rate, white blood cell (WBC) count, and packed cell volume (PCV), as well as higher serum chloride concentrations, compared to pretreatment values and the control group. Notably, on Day 3, the WBC count in the FMT group was significantly lower than in the control group (P = 0.04), and heart rate decreased over time in the FMT group.

 

Additionally, although three foals initially in the control group were later transferred to the FMT group, diarrhoea resolved in two of them after FMT treatment.

 

FMT was also associated with a greater diversity in the gut microbiota, with enrichment of beneficial bacteria such as the phylum Verrucomicrobiota, genus Akkermansia, and family Prevotellaceae. Previous studies have shown that Akkermansia is linked to the maintenance of the mucin layer in the intestines and can reduce bowel inflammation in humans. Members of the Prevotellaceae family have been associated with anti-inflammatory effects and improved intestinal health.

 

The authors concluded that FMT appears to be a safe treatment for foals with diarrhoea and can lead to some clinical and microbiota changes that suggest beneficial effects. 

 

However, further research is needed to confirm its impact on survival and long-term outcomes in affected foals.

 

For more details, see: 

 

Bell J,  Raidal SL,  Cuming RS,  Trope G,  Hughes KJ.  

Effects of fecal microbiota transplantation on clinical outcomes and fecal microbiota of foals with diarrhea. 

J Vet Intern Med.  2024; 38(5): 2718-2728.

https://doi.org/10.1111/jvim.17185