Ixodes ricinus: The importance of tick-borne disease in the UK and Europe

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The tick Ixodes ricinus, commonly known as the sheep tick, deer tick, or castor bean tick, is the
most widespread tick species in the United Kingdom and across much of Europe. It is medically and veterinary important because it can transmit a wide range of disease-causing microorganisms, known as tick-borne pathogens (TBPs), to humans, horses, livestock, wildlife, and pets. 

 

In the UK, I. ricinus is found mainly in areas with moist vegetation, rough grazing, heathland, woodland, and upland pasture. Large populations occur in southern England, Norfolk, the Scottish Highlands, Wales, the Lake District, and the North York Moors, although the species is spreading into new regions. The tick is considered a common and increasing problem in Britain, partly because warmer temperatures and milder winters linked to climate change improve tick survival.

 

Expanding deer populations, increased outdoor recreation, and greater contact between wildlife, horses, pets, and people also contribute to rising exposure. 

 

The most important disease carried by I. ricinus in the UK is Lyme disease, caused by bacteria from the Borrelia burgdorferi group. Lyme disease is the most common tick-borne infection affecting humans in Britain. Horses can also become infected, although clinical disease is less commonly recognised. Symptoms in horses may include lethargy, stiffness, lameness, muscle tenderness, behavioural changes, and poor performance.

 

The tick can also carry Anaplasma phagocytophilum, which causes equine granulocytic anaplasmosis. This disease may lead to fever, depression, limb swelling, jaundice, and reluctance to move. In addition, I. ricinus is capable of transmitting Babesia parasites, which infect red blood cells and can cause anaemia. Tick-borne encephalitis virus (TBEV), a virus affecting the nervous system, has also recently been identified in parts of the UK, although human cases remain rare. 

 

A recent Polish study led by Anna Rymaszewska investigated the occurrence of several TBPs in I. ricinus ticks collected from recreational forest areas, from ticks feeding on horses, and from red deer blood samples. The researchers used molecular diagnostic methods to identify the microorganisms present.

 

The study examined both “questing” ticks and feeding ticks. A questing tick is a tick actively searching for a host. Rather than jumping or flying, ticks climb vegetation and hold out their front legs in a behaviour called “questing.” When an animal or person brushes past, the tick attaches itself and begins feeding. 

 

The study found several pathogens in the ticks, including Borrelia afzelii, Borrelia garinii, Anaplasma phagocytophilum, and species of Rickettsia. B. afzelii and B. garinii are important causes of Lyme disease in Europe. B. afzelii is commonly associated with skin infections, while B. garinii is linked more closely with neurological disease. Rickettsia helvetica and related species may cause flu-like illness, fever, headache, and occasionally more serious disease in humans.

 

An important finding was the detection of multiple pathogens within single ticks or animals. Some ticks carried two, three, or even four pathogens simultaneously. This is significant because co-infections may increase disease severity, complicate diagnosis, and allow animals or humans to become infected with several diseases from one tick bite.

 

The study highlights the growing importance of tick surveillance and tick control in both veterinary and human medicine. Forest recreation areas, horse grazing land, and wildlife habitats can all act as hotspots for exposure. Understanding tick ecology and disease transmission is increasingly important for protecting horse health.

 

 

 

For more details, see:

 

Anna Rymaszewska, Katarzyna Kubiak, Małgorzata Dmitryjuk, Izabella Rząd, Lucyna Kirczuk.

Occurrence of tick-borne pathogens in questing ticks, ticks from riding horses, and red deer blood in Western Pomerania, Poland,

Veterinary Microbiology,(2026), Vol 315,110932,

 

https://doi.org/10.1016/j.vetmic.2026.110932

Wearable sensor to predict catastrophic injury risk in racehorses

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Catastrophic musculoskeletal injury (CMI) remains one of the most serious welfare challenges in Thoroughbred racing. Although safety has improved in recent years, fatal limb injuries still occur on raceday and during training, often with little visible warning. A new study led by researchers at Washington State University (WSU) suggests that wearable sensor technology, combined with advanced data analysis, could help identify horses at highest risk before an injury occurs.

The device involved in the study is a small, lightweight sensor worn in the horse’s saddle cloth that functions as an inertial measurement unit (IMU), combined with global positioning system (GPS) technology. It measures acceleration and movement in multiple directions and records approximately 2,400 data points per second. This allows the system to capture minute details of stride mechanics - such as symmetry, impact force, and limb movement patterns - that are far too subtle and too fast to be detected by the human eye, especially at racing speeds.

An algorithm processes the stride data and compares it to patterns collected from thousands of sound, high-performing horses and from those that later suffered fatal musculoskeletal injuries. Based on this comparison, each horse is assigned a risk score from 1 to 6, where a score of 1 represents the lowest risk and a score of 6 indicates the highest risk of future fatal injury.

The researchers analysed stride data from 28,481 races involving 11,834 Thoroughbreds at 10 racetracks across the United States. These data were collected between July 2021 and May 2024. During this time, 74 horses were fatally injured. Statistical analysis revealed a relationship between risk score and the likelihood of injury. Horses that received the highest score of 6 represented only 0.4% of total race starts, yet they accounted for 4% of all fatalities. When compared to horses with a score of 1, horses assigned a 6 were 44 times more likely (44.6 times, to be precise) to suffer a fatal musculoskeletal injury.

The research team conducted logistic regression analyses to explore whether other factors affected injury risk. Interestingly, age was not found to be a significant predictor, meaning that older horses were not necessarily more at risk than younger ones. However, male horses (stallions and geldings) were more likely to suffer fatal injuries than females. Race distance also played a role; horses competing in shorter races were at greater risk, possibly due to higher speeds and greater peak forces on the limbs. In addition, fatal injuries occurred more frequently on dirt and turf tracks than on synthetic all-weather surfaces.

These findings align with previous research showing that surface type and speed can influence limb loading and injury rates. They also reinforce the idea that many racing injuries are not sudden or random events. Necropsy studies have previously shown that as many as 93% of horses that suffered catastrophic injury had evidence of a pre-existing bone abnormality, such as microfractures or maladaptive bone remodelling. This new sensor technology provides a way to detect the biomechanical consequences of those underlying problems before they reach a critical point.

Dr Warwick Bayly, lead researcher and professor in WSU’s College of Veterinary Medicine, believes this technology could be used as a preventative screening tool. Horses identified as high-risk could undergo detailed veterinary examination, including lameness assessments and advanced diagnostic imaging (such as MRI or CT scanning if appropriate). Trainers and veterinarians could then adjust training intensity, allow additional rest, or pursue treatment before a catastrophic breakdown happens.

The technology was originally tested at WSU’s Hitchcock Research Racetrack - the only dedicated university-based racetrack in the USA - before being expanded to major racing venues including Saratoga, Belmont, Keeneland, Churchill Downs and Emerald Downs. Its success is part of a wider effort to improve racehorse welfare. Since 2009, raceday fatality rates in the U.S. have dropped from 2 deaths per 1,000 starts to 1.32 in 2023. While this is significant progress, every fatality is devastating for the horse, the people involved, and the public perception of the industry.

By identifying at-risk horses early and intervening, this technology has the potential to reduce fatal injuries, making it a promising and ethically important step forward in the future of horse racing science.

For more details, see:

Mc Sweeney, Denise, Yuan Wang, Scott E. Palmer, Mikael Holmströem, Kevin D. Donohue, Kelly D. Farnsworth, Macarena G. Sanz, David H. Lambert, and Warwick M. Bayly. 

Thoroughbreds deemed to be most at risk by inertial measurement unit sensors suffered a fatal musculoskeletal injury at a higher rate than other racehorses

Journal of the American Veterinary Medical Association (2025) published online ahead of print 

https://doi.org/10.2460/javma.25.04.0268

EVJ Special Focus: Advances in Diagnosing and Treating Musculoskeletal Disorders in Sport Horses

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Musculoskeletal problems are one of the main reasons sport horses lose training time, underperform, or retire early. 

The latest Equine Veterinary Journal (EVJ) Special Focus, edited by Maarten Oosterlinck and Rhiannon Morgan with guest editors Kyla Ortved and Hilary Clayton, gathers 21 studies from leading researchers to explore causes, diagnostic advances, and treatments for these conditions. The section is divided into three themes: aetiology, diagnostics, and therapeutics. There is also a podcast summarising the work.

Understanding Causes and Risk Factors

Osteochondrosis (OC), the most common developmental orthopaedic disease in horses, is linked to vascular failure in growing cartilage. Olstad summarises over a decade of research showing how this process can lead to different OC presentations, including osteochondritis dissecans.

In eventing, Cameron-Whytock et al. report that 36% of equine fatalities over 25 years were due to musculoskeletal injuries, mostly during cross-country. Lameness patterns in Australian campdraft horses, studied by Argue and Labens, showed 53% forelimb and 41% hindlimb involvement.

Spinal health is another focus. Spoormakers et al. found Warmbloods had higher rates of thoracic vertebral lesions (including osteoarthritis and kissing spines) than smaller breeds. Patricio et al. note that early detection and targeted rehabilitation for spinal articular dysfunction can extend performance careers.

Suspensory ligament (SL) injury remains a common problem, and Guest et al. review its anatomy, function, and variable treatment outcomes.

Advances in Diagnostics

Taddey et al. used inertial measurement units (IMUs) to quantify head and withers movement asymmetry, showing that even sound horses aren’t perfectly symmetrical.

Hansen et al. describe a new chronic myopathy in Icelandic horses causing poor performance and multi-limb lameness. For osteoarthritis (OA), Anderson et al. used metabolomic and proteomic profiling of synovial fluid to identify potential early diagnostic markers.

CT technology is expanding: Ogden et al. detail imaging the proximal limb and spine, while Hellige et al. explore CT myelography for detecting spinal cord compression. New standing CT techniques allow hoof imaging (Szabó et al.) and comparison with MRI for distal limb evaluation (Nagy et al.). MRI studies also include DDFT injuries (Scharf et al.) and proximal interphalangeal joint ligaments (Peeters et al.), as well as comparing MRI and radiography for hoof measurements (Bowkett-Pritchard et al.).

Treatment Innovations

Seery et al. assess how trimming affects hoof balance and load distribution, with implications for injury prevention. For SDFT tendinopathy, Blatter et al. report outcomes of tenoscopic desmotomy in Warmbloods. In back surgery, Connaughton et al. compare caudal and cranial wedge ostectomy for treating kissing spines.

Regenerative therapies are also advancing: Munevar Luque et al. test equine umbilical cord-derived mesenchymal stem cells combined with hyaluronic acid, showing promising results compared to HA alone.

“This special focus brings together the latest science and knowledge on multiple aspects of the diagnosis and treatment of Musculoskeletal disorders in sport horses” said Maarten Oosterlinck, deputy editor of the EVJ. “The practical, evidence-based studies present imperative reading for veterinary practitioners, to support their goal of providing the most advanced diagnostics and therapeutic approaches for sport horses with musculoskeletal issues.”  

 

The EVJ special focus issue on Musculoskeletal disorders in Sport horses can be found here:

 https://beva.onlinelibrary.wiley.com/toc/20423306/2025/57/5

 

The podcast in which the editors discuss the issue can be found here: 

https://www.podbean.com/ew/pb-yhq98-1928df1