New tool to aid worm control

  

A free online tool to help horse owners evaluate the risk of worm infection has been launched. 

 

This simple, user-friendly resource, titled ‘What’s Your Worm Risk?’, has been developed by Austin Davis Biologics in collaboration with equine industry.

 

Anthelmintic resistance poses a significant threat to equine health and welfare, with cases now reported in all common horse worms. Effective worm control begins with assessing a horse’s risk of infection, providing essential information for decisions regarding management, testing, and treatment.

 

The tool uses widely accepted principles of equine worm control to classify each horse's risk of infection as low, moderate, or high, based on details provided by the owner. It also accounts for the potential impact of grazing companions, where applicable.

 

Jacqui Matthews, a specialist in parasitology and director of veterinary science at Austin Davis Biologics, explains: “The tool is designed to support horse owners in assessing their horse’s risk of infection, helping them make informed decisions about testing and treatment.”

 

To reduce the risk of wormer resistance, experts recommend combining excellent pasture management—reducing worm transmission from paddocks—with regular testing to guide treatment decisions.

• Faecal worm egg count (FEC) tests provide an insight into worm egg shedding levels in manure.
• Antibody tests reveal the horse’s exposure to worm infections.

 

This approach minimizes the need for blanket wormer treatments, which are known to promote resistance and reduce the effectiveness of essential drugs.

 

The ‘What’s Your Worm Risk?’ tool has been optimised for use on smartphones, laptops, and desktop computers and is tailored specifically to UK conditions.

 

By integrating testing and evidence-based treatments into worm control plans, horse owners can protect their animals while reducing the risk of drug resistance in the equine population.

 

For more details, see: 

 

https://www.whatsyourwormrisk.com

New reporting initiative for clinical redworm disease in the UK

 Equine Infectious Disease Surveillance (EIDS) has launched RedWatch, a new initiative designed for vets to report cases of redworm disease in horses.

 

Based at Cambridge University, EIDS collects and analyses national disease data from diagnostic laboratories and veterinary practices across the UK. Their work provides valuable insights into the prevalence of equine infectious diseases. In addition to operating various surveillance programs, EIDS offers disease control advice and shares critical disease information through platforms like the International Collating Centre (ICC), EquiFluNet, and the Equine Quarterly Disease Surveillance Report, a collaborative effort with BEVA, Defra, and APHA.

 

Historically, large redworm infections—most notably caused by Strongylus vulgaris—have been significantly reduced in the UK due to the widespread use of anthelmintics. However, the overuse of these treatments has led to growing resistance, especially in small redworms (cyathostomes). As a result, there has been a shift towards reducing anthelmintic use and focusing on management-based strategies to control parasitic diseases.

 

Concerns remain, however, that reduced anthelmintic use could unintentionally alter the patterns of parasite-associated diseases. To address this, EIDS has introduced RedWatch, a targeted surveillance initiative.

 

RedWatch will collect and disseminate case data on diseases caused by small and large strongyles, including cyathostominosis and Strongylus vulgaris. Veterinary surgeons are encouraged to submit information via an online form, recording:

·       Vet and practice details

·       Case-specific information

·       Diagnostic methods

·       Clinical signs observed

·       Data about the premises and equine population

·       Potential risk factors

All submitted data will be securely stored and anonymised for public reporting. This will support education, awareness, and ongoing research into equine parasitology.

 

Large strongyles are often only detected during post-mortem examinations (PME) and are likely to be captured mainly through the Equine Quarterly Disease Surveillance report’s post-mortem surveillance section.  However, RedWatch will allow veterinary surgeons to report large strongyle cases that have not undergone an official PME.

 

"RedWatch is an exciting step in equine parasitology surveillance," said Fleur Whitlock, veterinary surgeon and epidemiologist at EIDS. "This initiative relies on veterinary surgeons sharing data and their engagement is key to filling knowledge gaps. By contributing case reports, vets can directly support efforts to prevent these devastating diseases and help pave the way for new tools like real-time reporting and risk warnings.”

 

EIDS is generously funded by the UK’s Thoroughbred industry and is based at Cambridge University.

 

For more details, download the latest Equine Quarterly Disease Surveillance report

https://equinesurveillance.org/landing/resources/reports/dsr20243.pdf

 

Veterinary surgeons can record cases at

www.equinesurveillance.org/redwatch

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

Does hand walking promote gut motility?

(c) Abby Khoriaty Dreamstime.com

 Hand walking in horses is a widely practiced exercise often used during recovery after surgery, and in rehabilitation. Its potential effect on gut motility may have benefits for horses prone to colic or recovering from gastrointestinal issues.

Amelia S. Munsterman and colleagues from the Department of Large Animal Clinical Sciences at Michigan State University's College of Veterinary Medicine in East Lansing, MI, conducted a study to evaluate the effects of hand-walking exercise on the myoelectrical activity in the cecum and left ventral colon (LVC) of healthy, fasted horses confined to stable rest. The research is published in the Journal of the American Veterinary Medical Association.

 

The researchers assessed gut activity using electrointestinography (EIG), a method that measures the electrical activity of the gastrointestinal tract. They also used ultrasonography and auscultation to monitor caecal and LVC contractions.

 

The study involved eight clinically healthy horses. To qualify for inclusion, the horses underwent a thorough physical examination and abdominal ultrasonography to rule out any gastrointestinal abnormalities or previous abdominal surgery.

 

The horses, which had previously lived out on pasture, were housed in 3m X 3m box stalls for the study, and fasted for 12 hours, with free access to water.

 

After a 30-minute baseline electrointestinography (EIG), horses were either stall rested or hand walked for 15 minutes. The research team repeated the EIG immediately afterwards and again after two hours. They also monitored caecal and LVC activity using ultrasonography and auscultation.

 

Their findings revealed no difference in gut motility between the box rested or hand-walked groups

 

The researchers conclude: “Brief hand walking as a single strategy to increase gastrointestinal motility did not affect contractility or EIG in normal horses.”

 

They suggest that further research is needed in clinical cases to confirm any benefits of hand walking.

 

 

For more details, see:

 

Munsterman, A. S., Rogers-Tirado, J. M., & Kottwitz, J. (2024). Electrointestinography, ultrasonographic contractility, and borborygmi of the cecum and colon are not altered by a single episode of hand walking exercise in healthy horses. 

Journal of the American Veterinary Medical Association (2024). 

https://doi.org/10.2460/javma.24.07.0486

Y chromosome reveals the global spread of Oriental stallions

(c) Sergey Uryadnikov Dreamstime.com

The development of modern horse breeds has been strongly shaped by stallions, making the male-specific part of the Y chromosome (MSY) a key genetic marker for studying their origins and spread.  

Researchers from the University of Veterinary Medicine Vienna (Vetmeduni), along with international partners, traced the lineage of modern breeds through stallions. They found that most horse breeds in Europe, Asia, and the Americas share common male ancestors, whose influence became widespread only in the past few centuries.

 

A full report of their work is published in the journal PNAS.

 

Horses have been deeply significant in human history, shaping cultures and geopolitical developments. Over time, human activities like migrations, diverse breeding goals, and selective breeding centered on stallions have created a complex genetic ancestry in horses. The Y chromosome, passed down through male lines, offers insights into the origins and historical impact of specific stallions on horse populations.

 

For their study, the researchers analysed a large number of modern breeds and reconstructed their paternal lineages over the last 1,500 years. The scientists identified three major recent breeding influences and highlighted two fundamental historical routes driving the spread of Oriental horses.

 

The research team analysed data from 1,517 stallions across 189 modern horse breeds, covering a wide range of traits and geographic areas. They were able to decipher the enormous influence of Oriental stallions over the last few hundred years, demonstrating the origin and widespread distribution of Arabian, English Thoroughbred and Coldblood stallions, and exposing the consequences of intense linebreeding.

 

“The majority of stallions worldwide carry Y lines that can be attributed to an only approximately 1,500-year-old so-called Crown haplogroup. The predominance of Crown lineages in modern horse breeds is the result of the enormous impact of stallions of “Oriental origin” in the past millennium,” the study’s first author, Lara Radovic from the Centre for Biological Sciences at Vetmeduni, explains. 

 

“The spread of Oriental horses was complex and started with the Muslim expansion. The similar spectrum of paternal lines in horse breeds from the Iberian Peninsula and the New World confirms the enormous distribution of horses of Oriental origin via the Iberian Peninsula after the Middle Ages,” Radovic adds. The survey also revealed a second major historical dissemination of horses from Western Asia, accompanied by the expansion of the Ottoman Empire. 

 

“Our study shows that MSY analysis can uncover the complex history of horse breeds,” says the study’s last author Barbara Wallner from the Centre for Biological Sciences at Vetmeduni. “By tracing the legacy of Oriental stallions, we have demonstrated the inseparability of horse and human history and deciphered former unknown connections between geographically and phenotypically different horse breeds. We have also highlighted the consequences of intensive animal breeding, which have led to the loss of breeding lines,” Wallner adds. 

 

According to Wallner, the work also presents new opportunities for capturing the historical development of breeding populations as a basis for meaningful decisions in breeding management in the future.
 

 

For more details, see:

 

L. Radovic, V. Remer, D. Rigler, E. Bozlak, L. Allen, G. Brem, M.Reissman, G.A. Brockmann, K. Ropka-Molik, M. StefaniukSzmukier, L. Kalinkova, 

V.V. Kalashnikov,  A.M. Zaitev, T. Raudsepp, C. Castaneda, I. von Butler-Wemken, L. Patterson Rosa, S.A.Brooks, M. Novoa‐Bravo, N. Kostaras, A. Abdurasulov, D.F.Antczak, D.C. Miller, M.S. Lopes, A. da Câmara Machado, G.Lindgren, R. Juras, G. Cothran, B. Wallner, 

The global spread of Oriental Horses in the past 1,500 years through the lens of the Y chromosome, 

Proc. Natl. Acad. Sci. U.S.A.(2024) 121 (49) e2414408121,

https://doi.org/10.1073/pnas.2414408121 

The role of equine practice in the downfall of antibiotics

(c) Amaviael Dreamstime.com

 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.