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