IVF progress

  

Researchers from the University of Florida Department of Animal Sciences have reported
progress in equine reproduction, demonstrating that frozen-thawed stallion sperm may be more effective for in vitro fertilisation (IVF) than fresh or chilled semen. The findings, published in the journal Reproductive Biology, could have significant implications for the performance horse industry.

In horse breeding, IVF has historically lagged behind its success in other species such as cattle. One major challenge has been the difficulty of achieving proper sperm function outside the body. In particular, stallion sperm require a process known as capacitation before they can penetrate and fertilise an egg. This involves a series of physical and biochemical changes that are highly sensitive to environmental conditions such as temperature and time.

The need for improved IVF techniques is especially relevant in the performance horse sector. Highly valuable mares are often selected for breeding, but not all are able to safely conceive or carry a pregnancy. Certain conditions, including uterine disease, prior foaling injuries, or lameness, may increase the risk associated with pregnancy. Additionally, some mares may be performing at their optimal level and cannot be withdrawn from competition for breeding purposes.

In such cases, producing an embryo via IVF and transferring it into a surrogate mare offers a safer alternative, protecting both the donor mare and the developing foal.

To better understand how to achieve successful fertilisation, the research team investigated how different types of semen - fresh, chilled, and frozen-thawed - respond under capacitating conditions. They also compared various sperm selection methods, including Percoll gradients, Swim-Up techniques, and microfluidic systems*. These approaches were assessed based on key indicators such as sperm motility, acrosome integrity, and biochemical markers like tyrosine phosphorylation.

The results revealed that temperature played a critical role. Incubating sperm at body temperature (38°C) reduced motility, whereas maintaining sperm at ambient temperature allowed optimal capacitation within approximately four hours. At this time point, sperm also showed the highest level of acrosome integrity, an important factor for successful fertilisation.

The research team found that frozen-thawed sperm performed better than fresh or chilled samples in the IVF setting. Although freezing and thawing can place mild stress on sperm cells, this stress appears to trigger changes that promote capacitation. As a result, frozen sperm were able to function effectively with fewer preparatory steps.

Further experiments confirmed fertilisation success through the observation of pro-nuclear formation and early embryo development. Notably, microfluidic sperm selection produced superior results compared to traditional Swim-Up methods, improving sperm quality and fertilisation potential.

Beyond the biological findings, the use of frozen sperm offers practical advantages. Unlike chilled semen, which must be used within a short timeframe, frozen semen can be stored indefinitely and thawed when needed. This flexibility allows veterinarians and breeders to better coordinate the timing of egg collection and fertilisation, making the IVF process more efficient and accessible.

This research represents a significant step forward after more than three decades of limited progress in equine IVF. By identifying conditions that support effective capacitation and demonstrating the advantages of frozen sperm, the study provides a foundation for improving embryo production in horses. For the equine industry, these advances could expand breeding options while prioritising the health and welfare of valuable mares.

 

For more details, see:

Joao D. de Agostini Losano, Jillian E. Guertin, Maura S. McGraw, Lana Katz, Vilceu Bordignon, Justin W. Callaham, Jose H.F. Pontes, Perla Fleury, Marc Maserati, Carly Turner, Bradford W. Daigneault,

Temporal characterization of conditions that promote functional capacitation of stallion sperm,

Reproductive Biology (2026) Vol 26, 2,101201,

https://doi.org/10.1016/j.repbio.2026.101201

 

 

*Percoll gradient centrifugation is a method that separates sperm based on their density. A liquid medium is layered in tubes at different concentrations, and the semen sample is placed on top. When the tube is spun in a centrifuge, sperm cells move through the layers depending on their density and quality. The most viable sperm - those that are motile and structurally normal - tend to settle into a specific layer, while debris, dead sperm, and less functional cells remain elsewhere. This method is widely used because it produces a relatively clean and concentrated sample of high-quality sperm.

Swim-Up technique relies on sperm motility rather than density. In this approach, a semen sample is placed at the bottom of a tube with a layer of culture medium above it. Over time, the most motile sperm actively swim upward into the medium. These sperm are then collected from the top layer. This technique mimics a natural selection process, as only the strongest swimmers are chosen. However, it can result in lower sperm numbers and may not always select for the best overall sperm quality, especially if motility is reduced.

Microfluidic sperm selection systems represent a more modern and precise approach. These systems, such as microfluidic sperm selection, use tiny channels that mimic aspects of the female reproductive tract. Sperm are introduced into a device where they must navigate through narrow pathways and fluid flows. Only sperm with good motility, proper morphology, and functional membranes can successfully pass through the system. This method reduces mechanical stress on the sperm compared to centrifugation and may better preserve their physiological state.

Feeding strategies for horses with severe asthma: effects on behaviour and welfare

    

Equine asthma is a chronic respiratory disease that can be triggered or worsened by inhaling
dust, mould, or other airborne particles commonly found in conventional dry hay. Managing the diet is an essential part of treatment, as feed type can influence not only respiratory health but also time budgets and welfare-related behaviours.

Recent research has compared the effects of feeding steamed hay and alfalfa pellets on horses suffering from severe asthma, shedding light on how different low-dust diets affect feeding behaviour, lung health, and overall well-being.

In a controlled study involving nine severely asthmatic horses, Antoine Symoens  and colleagues at the University of Montreal, Canada evaluated the effects of two low-dust feeding regimes - alfalfa pellets and steamed hay - on feeding duration, activity patterns, and gastric health.

The horses were housed indoors and first fed dry hay to induce a clinical flare-up of asthma. They were then placed on either steamed hay or alfalfa pellets for four weeks, using a crossover design so that each horse experienced both diets. Their behaviour was recorded for 18–22 hours at multiple stages during the trial, and gastroscopies were performed before and after each feeding period to assess gastric ulcers.

Results showed clear differences in eating patterns between the two diets. When fed steamed hay, horses spent a consistent proportion of their day eating - about 48% - both during the first and fourth weeks of feeding. In contrast, when horses were switched to pellets, the time they spent eating dropped significantly by roughly one-third in the first week. Interestingly, horses on the pelleted diet appeared to adapt by breaking up their feeding into shorter, more frequent meals, a pattern described as “fragmented eating.” This adjustment might help maintain some degree of natural foraging behaviour despite the rapid consumption time associated with pellets.

From a welfare perspective, steamed hay appears to preserve a more natural feeding time budget. Horses in the wild spend most of their day grazing, and maintaining this prolonged eating activity is associated with better digestive health and lower risk of behavioural issues such as boredom or stereotypies. Short feeding times, as seen with pelleted diets, can disrupt this pattern, potentially leading to frustration or undesirable behaviours.

However, feeding choices must also consider respiratory benefits. Earlier findings have shown that while steamed hay is much less dusty than untreated hay, it may be less effective than alfalfa pellets at improving lung function in asthmatic horses. Therefore, while steamed hay supports more natural feeding behaviour, pellets may provide a stronger advantage for respiratory management. Importantly, the study found that neither diet had an influence on the occurrence of squamous gastric ulcers, an encouraging finding for owners concerned about ulcer risk.

In practical terms, managing an asthmatic horse’s diet involves balancing multiple factors. Replacing dusty or mouldy hay with low-dust alternatives, such as haylage, steamed hay, or suitably formulated pellets, can help reduce respiratory irritation. For overweight or laminitis-prone horses, haylage may not be ideal due to its higher energy content, making steamed hay a more moderate choice. Combining different low-dust feeds could offer the best compromise, supporting both lung health and natural feeding behaviour.

In conclusion, when feeding horses with severe asthma, steamed hay helps maintain normal feeding time and behaviour, contributing positively to welfare, whereas pelleted diets offer greater respiratory benefits but may shorten eating duration. Selecting or combining these diets thoughtfully allows owners to meet both the physiological and behavioural needs of asthmatic horses.

 

For more details, see:

Antoine Symoens, Mathilde Leclère, Valentine André, Marion Desmarchelier,

Behavioral effects of two diets used for the management of severe equine asthma,

Journal of Veterinary Behavior, (2026) Vol 84, pp34-40,

https://doi.org/10.1016/j.jveb.2025.12.007

Response of horses and donkeys to fireworks in the UK

© Igor Akimov Dreamstime.com

   

Fireworks are widely used in the United Kingdom to mark celebrations such as Bonfire
Night and New Year's Eve. While these displays are enjoyable for many people, they can create significant challenges for animal welfare. Research has long shown that fireworks can cause stress and fear in companion animals such as dogs and cats, but comparatively little attention has been given to their effects on equids. 

A study by Stephanie Gerow and colleagues at the University of Lincoln aimed to address this gap by investigating how fireworks affect horses and donkeys in the UK.

The researchers conducted an anonymous online survey of equid owners aged 18 and over. In total, 1,234 horse owners and 232 donkey owners participated. The survey explored three main areas: how horses and donkeys respond to fireworks, what strategies owners use to reduce their impact, and owners’ opinions about firework use.

Horses are prey animals with a strong instinct for flight when faced with sudden or threatening stimuli. Loud, unpredictable noises such as fireworks can therefore trigger intense fear responses. Owners commonly reported behaviours such as running, kicking, bucking, and rearing. These reactions can be dangerous because frightened horses may attempt to escape from fields or stables, sometimes trying to jump fences or climb over stable doors. In severe cases, horses may injure themselves, other horses, or nearby people. Escaping horses can also pose a serious risk to road users if they enter nearby roads.

In the survey, eight percent of horse owners reported that their horse had suffered an injury associated with fireworks. Importantly, these injuries were usually indirect. They were caused by the horse’s reaction to the noise and lights rather than the fireworks themselves. Tragically, incidents involving fireworks have occasionally resulted in the death of horses after they panic and attempt to escape their environment.

Donkeys, in contrast, appeared to show fewer extreme responses according to owner reports. Only one donkey injury was reported in the survey. Researchers suggested that this difference may be related to the behavioural strategies used by the two species. Horses often respond to fear with a “flight or fight” reaction, which involves rapid movement and increases the risk of injury. Donkeys, however, may be more likely to adopt a “freeze” response when faced with a frightening stimulus. This behaviour may reduce the likelihood of injury, although it does not necessarily mean that donkeys experience less fear.

The survey also found that the type of horse may influence perceived reactions to fireworks. Horses used for hunting or competitive sport were generally reported to be less fearful than other horses. This may reflect differences in training, handling, or regular exposure to noisy environments.

Owners reported using a range of strategies to reduce the effects of fireworks on their animals. Common approaches included stabling horses during firework displays, remaining with the animal to provide reassurance, moving the animal to a different location away from fireworks, and playing music to mask sudden noises. Many owners also emphasised the importance of keeping animals in secure, well-lit environments with minimal hazards that could cause injury if the animal becomes frightened.

Although owners often considered these strategies effective, they are not always able to prevent stress or injury completely. Many of these measures also rely on advance warning of fireworks, which is not always available when displays are organised privately.

Most respondents (77%) supported tighter regulations on fireworks, particularly restrictions on when they can be used and reductions in their maximum noise levels. Overall, the findings highlight fireworks as a potential welfare concern for horses and, to a lesser extent, donkeys. Understanding how equids respond to loud and unpredictable stimuli is therefore an important part of equine management and welfare.

 

For more details, see:

 

Gerow SL, Clegg SR, Cooke AS.

Horse and donkey owners' perspectives on fireworks and their impact on equids in the UK.

Anim Welf. (2026) 35:e11.

https://doi.org/10.1017/awf.2026.10068

How Artificial Intelligence could improve fracture detection in horses

Researchers at the Royal Veterinary College (RVC) are exploring how artificial intelligence (AI) could help veterinarians detect fractures in animals more quickly and accurately. Their work has been shortlisted for the STEM for Britain 2026 award and highlights how technology developed for human medicine can also benefit animal health and welfare.

Fractures are a major concern in Thoroughbred racehorses. These injuries can affect both a horse’s welfare and its racing career, and in severe cases they can be life-threatening. Studies estimate that around 10% of racehorses experience a fracture during training, while bone injuries occur in roughly 1.3 per 1,000 starts in flat racing. Because of this risk, early and accurate detection of bone damage is extremely important.

However, diagnosing fractures is not always straightforward. Veterinarians usually rely on radiographs (X-rays) to assess suspected bone injuries. While X-rays are very useful, identifying fractures on these images can be challenging. Small cracks or subtle changes in bone structure may be difficult to see, and image quality or the angle at which the X-ray is taken can also affect interpretation. As a result, there is growing interest in using technology such as AI to support clinical decision-making.

The RVC research team developed an AI system designed to analyse medical images and identify fractures. The study was led by Associate Professor of Statistics Dr Ruby Chang, with the research carried out by Dr Hanya Ahmed. To train the system, the researchers created a large database of images that included 100 equine fracture cases collected from two UK equine hospitals and from published studies. They also included 70 feline fracture cases and around 4,000 human fracture images from a public database.

The AI system works in three stages. First, it identifies the type of medical image being analysed, such as an X-ray, CT scan, or MRI scan. Next, it determines the angle or projection of the image. Finally, it analyses the image to detect whether a fracture is present and to pinpoint its exact location.

One particularly interesting feature of the study is the use of a technique called transfer learning. In transfer learning, an AI model is first trained on a large dataset (in this case, thousands of human fracture images). The knowledge it gains is then adapted to a smaller dataset from another field; in this case, veterinary medicine. Because there are far fewer veterinary medical images available for training, this approach helps overcome one of the main challenges of developing AI systems for animal healthcare.

Using this method, the AI system was able to detect and locate fractures in horses with accuracy levels between 71% and 84%, despite having a relatively small number of equine images to learn from. The system also achieved very high accuracy when identifying image types and projections, reaching more than 96% accuracy in some stages of the analysis.

The results suggest that AI could become a valuable support tool for veterinarians. By helping identify fractures more quickly and reliably, AI-assisted systems may reduce uncertainty in diagnosis and allow treatment to begin earlier. This could improve recovery outcomes for horses and other animals.

The research team is now expanding the project through collaboration with the Hong Kong Jockey Club. The next goal is to investigate whether AI can detect early bone changes before a fracture occurs. If successful, this could help prevent serious injuries in racehorses and improve welfare within the sport.

Although the current study focuses on horses, the approach could also be adapted for other species such as cats, dogs, and potentially humans. Overall, the research demonstrates how advances in AI and medical imaging could play an increasingly important role in the future of veterinary diagnostics.

 

For more details, see:

Ahmed, Hanya T., Dagmar Berner, Qianni Zhang, Kristien Verheyen, Francisco Llabres-Diaz, Vanessa G. Peter, and Yu-Mei Chang. 2026.

Bridging Species with AI: A Cross-Species Deep Learning Model for Fracture Detection and Beyond

Bioengineering 13, no. 2: 213.

https://doi.org/10.3390/bioengineering13020213

Does starting racehorses early affect their careers? Insights from a German study

 

© Nataliavo Dreamstime.com

When should racehorses begin training and competition? This is a long-standing question in equine science and
welfare. While many horses in other disciplines do not start ridden work until they are around three or four years old, Thoroughbred racehorses are often introduced to training much earlier. A recent study using data from German Thoroughbred racing has explored whether starting training and racing at a young age affects a horse’s racing career.

The research, led by Mailin Hein and colleagues at the University of Veterinary Medicine Hannover in collaboration with Dr Monica Venner from the Equine Clinic Destedt, analysed historical racing data to investigate whether early training leads to shorter or less successful careers. The team used records from the German Racehorse Association, examining the racing histories of 600 Thoroughbred horses.

Racehorses typically begin training at 18–24 months of age and may race as two-year-olds. However, horses do not reach full skeletal maturity until around six to eight years of age, meaning their bones and joints are still developing during early training. Because of this, some experts question whether starting intense work too early could increase injury risk or shorten a horse’s racing career.

The debate is particularly relevant in Germany. German animal welfare legislation generally prohibits training or competing with horses younger than 30 months, although Thoroughbred racing is currently exempt while researchers investigate the welfare implications of early training.

The researchers carried out a retrospective study, meaning they analysed existing records rather than conducting a new experiment. The 600 horses in the dataset were divided into three groups depending on when they began training and racing:

• Early training / early racing – horses that entered training between 16 and 24 months and raced as two-year-olds
• Early training / late racing – horses trained early but did not race until after the age of two
• Late training – horses that began training later, between 25 and 30 months

The researchers compared several indicators of racing success between the groups. These included career length, performance ratings, total number of races, and lifetime earnings.

One interesting finding was that sex influenced career length. Geldings (castrated male horses) tended to have longer racing careers than other horses. This is likely because stallions and mares may retire earlier to enter breeding programmes, while geldings do not have this option. Because of this difference, the researchers looked at geldings as a separate group.

Among geldings, horses that started racing at two years old achieved higher maximum performance ratings than those that first raced at three years of age or later. Importantly, the early-racing group did not show shorter racing careers compared with horses that started racing later.

Overall, the study found no evidence that early training or racing at two years old had a negative effect on career length or performance in the horses analysed.

The findings suggest that, at least in this group of German Thoroughbreds, beginning training and racing at a young age did not appear to reduce racing success or shorten careers. However, the researchers emphasise that the results should be interpreted carefully.

Because the study used historical data, it cannot fully explain why some horses started racing earlier than others. For example, horses that mature physically earlier may naturally be selected to race sooner. Horses with health problems may also leave training early and therefore not appear in racing records.

The researchers suggest that future studies should include veterinary records, training information, and management factors, such as housing conditions and workload. Understanding these factors could help scientists evaluate how a horse’s physical development, health, and mental wellbeing influence its ability to cope with early training.

Ultimately, research like this aims to improve the welfare and management of racehorses, helping trainers and veterinarians make evidence-based decisions about when young horses should begin their athletic careers.

 

For more details, see: 

 

Hein, Mailin, Nina Volkmann, Jeanette Probst, Nicole Kemper, and Monica Venner. 2026.

Thoroughbred Geldings′ Career: Influence of Age at the Start of Training and Racing

Animals 16, no. 4: 576.

https://doi.org/10.3390/ani16040576

Free articles on equine infectious disease and Microbiology in EVJ Special Collection

© Golop Dreamstime.com

The March 2026 issue of Equine Veterinary Journal (EVJ) highlights major advances in equine infectious disease and microbiology, with a Special Collection dedicated to the equine microbiome. The issue, which is free to access for 12 weeks, features 30 research papers spanning a wide range of diseases, body systems, and pathogens. Many of the studies involve international collaboration, reflecting the global importance of managing infectious diseases in horses.

Equine infectious disease remains a key research focus for veterinarians and scientists because of its impact on horse health, welfare, and the equine industry. The special issue identifies three major themes: the importance of national disease surveillance programmes, the need for accurate and definitive diagnoses, and the value of comparing diseases across different animal species to better understand how pathogens behave.

Several studies focus on improvements in diagnostic techniques, particularly for equine fever, equine influenza, and gastrointestinal parasites. These advances aim to support faster detection of disease and enable earlier implementation of biosecurity measures, which can help reduce transmission between horses.

Research into gastrointestinal diseases also features prominently. Studies explore the use of metabolic profiling to detect equine proliferative disease earlier in foals, investigate possible causes of colitis, and emphasise the importance of additional diagnostic testing for chronic hepatitis and liver failure in cases linked to hepacivirus infection. Together, these findings may support earlier intervention and improved disease management.

Antimicrobial resistance is another significant area of concern. One survey found that nearly 40% of hospitalised horses received at least one antimicrobial treatment. Research linked to colic surgery suggests that using antimicrobials for more than 24 hours after surgery is unnecessary for preventing complications, highlighting opportunities to reduce antibiotic use and slow the development of antimicrobial resistance.

Several papers examine diseases affecting multiple body systems. For example, updated guidance on equine botulism emphasises its importance as a differential diagnosis when horses show neurological signs. Other studies investigate multisystem diseases by comparing similar infections in other species, helping researchers better understand how diseases develop and present in horses.

Blood-related infectious diseases are also discussed. Two systematic reviews examine equine trypanosomiasis, focusing on its prevalence, management, and control strategies. Another study introduces a new diagnostic tool for detecting Theileria haneyi, a parasite associated with equine piroplasmosis, and reports the first evidence of its presence in China.

Regionally important diseases are highlighted through research on Hendra virus, which uses government and field data to study how domestic horses may act as bridging hosts for zoonotic pathogens. Another study shows that horses infected with African Horse Sickness virus can develop severe blood clotting disorders that cause significant bleeding. Research also suggests that equine encephalosis virus should be considered when diagnosing African Horse Sickness in regions where both diseases occur.

The issue also examines reproductive health, with one study linking Escherichia coli infection to reduced fertility in Thoroughbred broodmares. Another uses multi-omics technology to study nocardioform placentitis, proposing that the condition be renamed mucoid placentitis due to the variety of bacteria involved.

Respiratory disease research forms a major section, including several studies on strangles. Findings emphasise the importance of screening, quarantine, monitoring, and disease reporting to improve prevention. Additional studies investigate respiratory disease caused by Rhodococcus equi, equine influenza vaccination strategies, and the use of air sampling in stables as a non-invasive surveillance method for equine herpesvirus.

Other research explores infectious skin diseases and rare ulcerative conditions, demonstrating the importance of obtaining accurate diagnoses and comparing disease patterns across species when treatment data in horses is limited.

The Special Focus section also includes a dedicated collection on the equine microbiome, updating earlier research published in 2019. This collection highlights rapid progress in understanding the complex communities of microorganisms that influence equine health.

Overall, the research presented in this EVJ issue aims to improve disease detection, diagnosis, treatment, and prevention. These advances are expected to strengthen equine welfare globally while supporting the livelihoods of communities that depend on horses for work and transport.

The Special Focus Issue is available here:

 https://beva.onlinelibrary.wiley.com/toc/20423306/2026/58/2