Cloning Offers New Hope for Genetic Diversity in Przewalski’s Horses

(c) Slowmotiongli | Dreamstime.com

A recent report highlights how cloning from cryopreserved cells can help increase genetic diversity in Przewalski’s
horses—an endangered species whose entire population today descends from a very limited number of wild ancestors.

The Przewalski’s horse (Equus przewalskii), once extinct in the wild, was saved through being bred in captivity and later reintroduced into its native habitats. This recovery program has been highly successful - with approximately 3,000 individuals alive today. However, it is important to recognise that all these horses trace back to just 12 wild-caught animals, captured between 1898 and 1947. As a result, the current global population is genetically narrow, with only five founder lineages represented in today's horses.

To address this genetic bottleneck, scientists are exploring advanced reproductive technologies, including cloning from cryopreserved cells. This approach could either restore lost genetic variation or amplify the presence of underrepresented lineages in the population. Such efforts rely on biological materials preserved in biobanks specifically for conservation purposes.

Since the 1970s, the San Diego Zoo Wildlife Alliance’s Frozen Zoo® - a major component of their Biodiversity Bank - has stored cells and tissues from 575 Przewalski’s horses spanning many generations. Among these samples was one from a stallion known as Studbook Number 615, or "Kuporovitch," who lived from 1975 to 1998. Despite his valuable genetics, Kuporovitch was underrepresented in the breeding program, making him an ideal candidate for cloning.

In a study published in the journal Animals, Ben Novak and colleagues reported the successful birth of two healthy clones of Kuporovitch. These clones were created using cross-species somatic cell nuclear transfer - a method in which the nucleus of a preserved Przewalski’s horse cell is inserted into an enucleated domestic horse ovum (egg), which is then implanted into a domestic horse surrogate mother. The first clone was born in 2020, followed by a second in 2023.

Both clones were genetically verified using standard pedigree genotyping, and one clone’s identity was further confirmed through whole-genome sequencing. 

The research team point out that this is the first time multiple clones of an endangered species have survived the perinatal period, marking a significant achievement in conservation science.

They add that, although only two clones were produced, both attempts at cloning were successful, demonstrating the reproducibility and reliability of cloning for genetic rescue purposes for the endangered Przewalski’s horse. 

This breakthrough makes the Przewalski’s horse only the fifth endangered species to be successfully cloned, and one of the first where cloning has been used as an active tool for conservation management. It opens the door to more strategic use of biobanked genetic material in future recovery efforts - not just to prevent extinction, but to enrich and diversify the genetic makeup of rebounding populations.

 

For more details , see: 

 

Novak, Ben J., Oliver A. Ryder, Marlys L. Houck, Kelcey Walker, Lexie Russell, Blake Russell, Shawn Walker, Sanaz Sadeghieh Arenivas, Lauren Aston, Gregg Veneklasen, and et al. 2025. 

Endangered Przewalski’s Horse, Equus przewalskii, Cloned from Historically Cryopreserved Cells 

Animals (2025) 15, no. 5: 613.

https://doi.org/10.3390/ani15050613

Leg mites and CPL in Belgian draft horses

(c) Hortensja Buckietowa CCbySA4.0

 A recent study provides evidence of a strong link between Chorioptes bovis mite infestation and
Chronic Progressive Lymphoedema prevalence in Belgian draft horses.

Chronic Progressive Lymphoedema (CPL) is a debilitating condition of the lymphatic system in horses, characterised by chronic inflammation, fluid accumulation, and progressive skin changes. Over time, the skin becomes rough, scaly, and thickened, with the formation of deep folds and creases. The skin folds can trap dirt and moisture, creating an ideal environment for bacterial and fungal infections.

 

In advanced cases, horses may experience pain and stiffness, leading to lameness.

CPL occurs most commonly in draft and heavy horse breeds, particularly those with heavily feathered legs. Such breeds are also prone to infection with Chorioptes bovis (mange mites)

Commonly affected breeds include: Shire Horses, Clydesdales, Belgian Draft Horses.

 

A study conducted by Marieke Brys and colleagues at the Faculty of Veterinary Medicine, Ghent University, Belgium, investigated the prevalence of CPL and Chorioptes bovis mite infestation in two horse breeds. A full report of their work is published in Veterinary Research Communications.

 

The research team examined 156 Belgian draft (also known as Brabant) horses and 142 Belgian warmblood horses.

 

They performed clinical examinations to assess for signs of CPL and took skin scrapings from the lower legs to detect the presence of Chorioptes bovis mites, a common cause of mange in horses.

 

They found that 144 out of 156 Belgian draft horses (92.31%) were infested with Chorioptes bovis mites. One hundred and twenty-six of the Belgian draft horses (80.77%) showed clinical signs of CPL.

 

In contrast, none of the 142 Belgian warmblood horses showed signs of CPL or mite infestation, highlighting a stark contrast between the two breeds.

 

The researchers found a significant association between mite infestation and CPL prevalence in Belgian draft horses. Horses infested with C. bovis were nearly twice as likely to exhibit CPL compared to non-infested horses.

 

The study noted a substantial absolute increase in CPL prevalence among mite-infested horses, indicating that mite infestation may contribute to the development or exacerbation of CPL.

 

The study provides compelling evidence of a strong link between Chorioptes bovis mite infestation and CPL prevalence in Belgian draft horses. The findings underscore the need for effective mite management strategies to reduce the incidence and severity of CPL, ultimately improving equine welfare and quality of life.

 

The researchers concluded that effective mite management is important for reducing the burden of CPL in draft horses. 

For more details, see: 

Brys M, Claerebout E, Saey V, Chiers K. 

High prevalence of Chorioptes bovis: an important factor in chronic progressive lymphedema in Belgian draft horses. 

Veterinary Research Communications (2025);49(3):129. 

https://doi.org/10.1007/s11259-025-10695-y

Discovery links genes to performance-limiting disease in Thoroughbred racehorses

(c) Miltudog Dreamstime.com

 New research has identified specific genetic markers linked to Recurrent Laryngeal Neuropathy (RLN), a disease that significantly impacts the performance of Thoroughbred racehorses. This discovery, hailed as a major step forward in combating this debilitating condition, paves the way for the development of a genetic test to identify horses with a threefold increased risk of developing RLN. 

Often referred to as laryngeal hemiplegia or "roaring," RLN is an upper respiratory tract (URT) disorder that affects up to 18% of Thoroughbred horses. The condition is characterised by the progressive degeneration of the recurrent laryngeal nerve, which controls the muscles that open the horse’s airway. As the disease progresses, airflow during exercise becomes restricted, leading to laboured breathing, reduced oxygen intake, and impaired athletic performance.

 

RLN represents a significant challenge for the Thoroughbred racing industry due to its economic and competitive implications. While pre-purchase examinations, including upper respiratory endoscopy ("scoping"), can detect RLN, resting evaluations in young horses often fail to identify the disease or predict its future onset.

 

To tackle these challenges, researchers at University College Dublin, in collaboration with Equinome and a world-class Thoroughbred training facility, conducted an extensive study funded by Research Ireland. The research team employed state-of-the-art diagnostic methods, including resting and overground exercising endoscopy of the upper airway, as well as laryngeal ultrasonography. This rigorous approach ensured accurate phenotyping of horses as either RLN cases or controls.

 

The study analysed over 200 Thoroughbred horses in training, utilizing both clinical evaluations and genetic testing. The case-cohort group was supplemented with detailed questionnaires to capture additional phenotypic data. A full report of the research is published in the Equine Veterinary Journal.

 

Using advanced DNA technologies, researchers conducted a genome-wide association study (GWAS) to identify genetic variants associated with RLN. They genotyped 43,831 single-nucleotide polymorphisms (SNPs) from 235 horses (110 RLN cases and 125 controls) and estimated the heritability of the trait. The findings revealed a set of genetic markers that significantly contribute to RLN risk, independent of other factors such as height.

 

This discovery is particularly important because it confirms a genetic predisposition to RLN and identifies specific markers that could be used to predict the disease in Thoroughbreds.

This research marks a significant advance in equine genetics and respiratory health, offering new hope for addressing RLN, a disease that has long plagued the Thoroughbred racing industry. The ability to identify horses with a higher genetic risk for RLN has far-reaching implications for the Thoroughbred racing industry. 

 

The next step will involve translating these findings into a practical genetic test that can be readily adopted by breeders, trainers, and veterinarians.

 

UCD Professor in Equine Genomics and Chief Science Officer at Equinome, Emmeline Hill said the new findings would “lay the groundwork for the development of a genetic test to improve the welfare of horses that have a genetic predisposition to the disease. 

“As well as identifying horses with an increased risk of disease, this new information could also inform breeding guidance to reduce the incidence of the disease and provide targets for new therapies.”

Project lead Lisa Katz, UCD Professor in Equine Internal Medicine, added: “Understanding the genetic risk of your horse for roaring can help with early intervention and management. This might include monitoring highly predisposed horses more closely and considering surgical interventions at an earlier stage to improve treatment success.”

 

For more details, see: 

 

A genome-wide association study for recurrent laryngeal neuropathy in the Thoroughbred horse identifies a candidate gene that regulates myelin structure

Charlotte L. McGivney, Beatrice A. McGivney, Gabriella Farries, Katie F. Gough, Haige Han, Amy R. Holtby, David E. MacHugh, Lisa Michelle Katz, Emmeline W. Hill

Equine Vet J (2025)

https://doi.org/10.1111/evj.14461

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 

Role of in-breeding in pregnancy loss

 A recent study conducted by the Royal Veterinary College (RVC) in collaboration with Cornell University sheds light on the role of inbreeding in mid and late-term pregnancy loss (MLPL) among UK Thoroughbreds. Interestingly, while inbreeding does impact MLPL, it has little effect on early pregnancy loss (EPL).

The research specifically explores the influence of genomic inbreeding levels on late-term pregnancy loss in horses. These findings provide valuable insights for breeding practices, which can help inform mating decisions to reduce the risk of miscarriages in Thoroughbreds.

 

Inbreeding, the mating of related individuals, is a common practice in the livestock industry and can be beneficial in controlled breeding programs for consolidating desirable traits within a population. However, excessive inbreeding heightens the likelihood of producing offspring with harmful homozygous recessive genotypes. This can lead to genetic disorders, reduced fertility, and decreased overall population fitness.

 

Approximately five to ten percent of equine pregnancies result in early pregnancy loss (EPL), while seven percent are lost between Day 70 of gestation and 24 hours postpartum (MLPL). Despite this, prior to this study, there had been no genomic analysis of the correlation between inbreeding levels and pregnancy loss in horses.

 

Led by Dr. Jessica Lawson, Alborada Trust Research Fellow at the RVC, and Professor de Mestre at the Baker Institute for Animal Health at Cornell University, along with former RVC PhD student Dr. Charlotte Shilton, the research team analysed DNA samples from 189 individuals. These samples included allantochorion and foetal DNA from early pregnancy loss (EPL) cases (n=37, gestation age 14–65 days), mid and late-term pregnancy loss (MLPL) cases (n=94, gestational age 70 days–24 hours post parturition), and hair or blood samples from adult UK Thoroughbred controls (n=58).

 

The study revealed that Thoroughbred pregnancies lost in mid and late gestation (MLPL) had significantly higher inbreeding metrics compared to UK Thoroughbred adult controls. Conversely, pregnancies lost early in gestation (EPLs) showed no significant difference in inbreeding metrics compared to controls.

 

These findings emphasise the importance of informed mating decisions in the Thoroughbred breeding industry. Moreover, they stress the need for further research to identify and characterise genomic changes that may prove detrimental to pregnancy.

 

Dr Jessica Lawson, Alborada Trust Research Fellow at the RVC, said: “This research provides critical evidence showing that mating highly related individuals does have a tangible effect on our breeding operations, as there is a real risk of a mare losing her pregnancy late in gestation and failing to produce a foal at all that season. 

 

“The take home from our work should be to carefully consider breeding choices that involve mating of highly related individuals as, ultimately, this may increase the chance of the foal inheriting mutations which may not be compatible with life. We are already working on the next step, looking to identify these changes so more specific advice can be provided in the future”.

 

This research was funded by the Thoroughbred Breeders Association, Horserace Betting Levy Board, the Alborada Trust, and partial PhD studentship funding from the Royal Veterinary College's Paul Mellon Trust for Equine Research.

 

For more details, see: 

Lawson JM, Shilton CA, Lindsay-McGee V, Psifidi A, Wathes DC, Raudsepp T, de Mestre, AM.

Does inbreeding contribute to pregnancy loss in Thoroughbred horses? 

Equine Vet J. 2024.

https://doi.org/10.1111/evj.14057

 

 

Edited press release. Read the original press release:

https://www.rvc.ac.uk/equine-vet/news/new-rvc-research-finds-inbreeding-is-contributing-factor-to-mid-and-late-term-pregnancy-loss-in-thoroughbreds

Collagen link to Thoroughbred fracture risk

 

Recent research conducted by the Royal Veterinary College (RVC) sheds light on the genetic factors contributing to bone fractures in Thoroughbred horses. The study reveals that horses with diminished levels of collagen type III have a higher risk of fractures.

Previously, the underlying genetic mechanisms behind these fractures had remained elusive. However, these new findings have enabled the RVC to identify a novel DNA variant associated with fractures, impacting the expression of collagen type III.

 

Bone fractures are common in Thoroughbred racehorses, due to the forces the bones can experience, and are a leading cause of euthanasia. Approximately 60 horses each year are euthanised on UK racecourses as a result. However, fracture is a complex condition, with both environmental and genetic risk factors affecting a horse’s susceptibility.

Led by Dr. Debbie Guest, Senior Research Fellow at RVC, the team developed a polygenic risk score to gauge disease susceptibility based on various genes. They were then able to use this information to select cells from horses whose risk placed them at the extreme ends of the population with either very low or very high risk. These cells were then used in laboratory studies to establish a cell model and investigate the genetic factors involved in fracture risk.

 

The research team’s findings indicate that bone cells from horses predisposed to fractures express collagen type III at reduced levels due to alterations in their DNA sequence in the region which controls how much collagen III is produced. 

This discovery provides a crucial step forward in identifying genetically high-risk horses. By understanding the genetic causes of fractures,, this research can help identify, diagnose, and manage high-risk horses, improving the health and welfare of Thoroughbreds in the racing industry.

 

Ongoing research aims to validate the risk-scoring system across different horse populations and further explore genetic factors using the established cell model.

 

For more details, see:

 

Palomino Lago, E.; Baird, A.; Blott, S.C.; McPhail, R.E.; Ross, A.C.; Durward-Akhurst, S.A.; Guest, D.J. 

A Functional Single-Nucleotide Polymorphism Upstream of the Collagen Type III Gene Is Associated with Catastrophic Fracture Risk in Thoroughbred Horses. 

Animals 2024, 14, 116. 

https://doi.org/10.3390/ani14010116 

Online Seminars from Horses Inside Out

Horses Inside Out have announced a series of online seminars to be held later this year. With
three expert speakers, these seminars are aimed at equine professionals and promise to enhance your knowledge in equine health, welfare, genetics, and performance.

 

Understanding Orthopaedic Problems with Dr Jessica Kidd : Saturday, 7 October 2023 

Dr Jessica Kidd will share her extensive knowledge of orthopaedic issues in horses, including caudal neck pain, neuropathic pain, and Wobbler's Syndrome. She will also address regenerative medicine, dispelling myths about joint injections and stem cell therapy. The seminar will cover common problem areas in horses such as the back, kissing spines, supraspinous ligament desmopathy, facet joint arthritis, and the sacroiliac region.

https://www.horsesinsideout.com/understanding-orthopaedic-problems

 

Nature Versus Nurture - Genetic Insights with Dr Andrew Hemmings : Saturday, 4 November 2023. 

Discover the fascinating world of equine genetics with Dr Andrew Hemmings. The seminar will explore evolutionary perspectives on anatomy, management, and behaviour in horses. You will learn about the inheritance of simple traits, such as coat colour, and delve into more complex traits like racing performance and abnormal behaviours, all while examining the interaction between genes and the environment.

https://www.horsesinsideout.com/nature-nurture

 

Equine Comfort and Performance with Dr Chris Pearce & Gillian Higgins : Saturday, 2 December 2023. 

This one-day seminar will focus on the integral role of dentistry, bridle fit, and understanding anatomy in equine comfort and performance. Dr Chris Pearce and Gillian Higgins will discuss the complex anatomical and biomechanical connections of the horse's head and how it can impact the rest of the body and performance. Dental disease, bit, and bridle fit can affect performance, and recognizing signs of discomfort is crucial.

https://www.horsesinsideout.com/getahead

Is it possible to breed less “spooky” horses?

Identifying genes that influence horses
tendency to react to danger (c) UF/IFAS

Wild horses possess an instinct to stay vigilant, constantly on guard against potential predators. This innate behaviour remains ingrained even in domesticated horses, causing them to be easily frightened and alert to potential dangers. 

 

Horses often struggle to differentiate between genuine threats and harmless objects, such as a plastic bag floating past a riding arena. As a result, some horses may react to these perceived dangers by rearing, bolting, or bucking, creating hazardous situations for both themselves and their riders.

 

University of Florida researchers are working to identify genes that influence horses’ tendency to react to these “spooky” plastic bags. Identifying these genetic traits would be a first step towards one day selecting or breeding horses for the temperament types we prefer. These research results might be a decade away.

 

Samantha Brooks, associate professor of equine genetics at the University of Florida Institute of Food and Agricultural Sciences, along with her team, conducted an experiment on several groups of young horses from the UF/IFAS breeding program to gain insights into startle responses.

 

The horses wore wireless heart-rate monitors and were loose in a round pen. At set intervals, an umbrella was opened quickly within the animals’ line of sight. The team analysed the animals’ behaviour and change in heart rate throughout and after the initial startle reaction.

 

“We can’t read their minds,” said Brooks. “Their heart rate tells us what is going on inside that we cannot see from reading their body language alone. It was interesting to see the stories their heart rates told us.”

 

The team found that two clear groups of horses emerged from the data. The first group was startled by the umbrella opening, had a spike in heart rate, maintained a reactive or hyper-alert state including more time spent looking and moving away from the umbrella. The second group startled much like the first group to the umbrella opening, but with a different outcome. The horses experienced a spike in heart rate but then calmed quickly and carried on with their day. These animals perceived the stimulus and found it startling but did not to go through the behavioural patterns of avoidance and fear like the first group.

 

“Horses have adapted over thousands of years to live with people,” said Brooks. “Some of those changes include a reduction in startle response and are really helpful to better understand the horses we work with today.”

 

Now that two clear groups have emerged, the team will take this information and develop a study to differentiate the genetic components that make up how horses react to fear. Blood and hair samples were taken from each horse in the study for future analysis.

 

They plan to conduct a genome-wide association study (GWAS) in which the genome of the horses is scanned to identify genetic variations that differ between the two groups, By analysing a large number of genetic variants across the genome, they hope to identify regions or specific genetic markers that are associated with behavioural startle reactions.

 

Knowing how genetics influence behaviour can help horses and owners find their right fit.

 

“Understanding each horse’s genetic makeup will help you understand the type of animal you need,” said Brooks. “If we learn early on what this animal’s natural tendencies are most likely to be, we can make educated decisions on training and future careers to give the horse the best shot to grow into their potential, rather than becoming a problem or danger.”

 

Additionally, understanding a horse’s reaction to uncomfortable situations can make a difference in how they are handled for medical procedures, transportation and more.

 

“It’s important to know these traits because it can impact how we care for horses overall,” said Barclay Powell, a Ph.D. student working on the project. “This will be hugely important to the veterinary field as well. It’s not only helpful for the people handling the animals, but also for the horses’ welfare.”

 

“It doesn’t matter if the horse is a racehorse, therapy animal or driving a carriage, an unplanned startle response is generally a problem,” said Brooks. “We are just beginning to scratch the surface of this. It might take us 10 years or more to really have a clear understanding, but it is worth the effort.”

 

Funded by the National Institute of Food and Agriculture, this project was a collaboration between scientists and students studying equine genetics, behaviour and welfare science.

 

For more details, see:

 

Behavioral and Physiological Reactions to a Sudden Novel Object in the Weanling Horse: Quantitative Phenotypes for Future GWAS

Barclay B. Powell, Kelsey C. Horvath, Tyeler L. Gilliam, Kimberly T. Sibille, Andreas Keil, Emily K. Miller-Cushon, Carissa L. Wickens and Samantha A. Brooks

Genes 2023, 14(3), 593;

 https://doi.org/10.3390/genes14030593

Tracking donkey domestication

(c) Demidoff. Dreamstime.com

For thousands of years donkeys have played an important part in human progress. They have 
supplied power for farm work, and provided transport, proving particularly useful in semi-arid and otherwise inaccessible areas.

 To understand the history of the donkey’s domestication, teams at the Centre for Anthropobiology and Genomics of Toulouse (CNRS/ Université Toulouse 3 Paul Sabatier) and scientists from 37 laboratories around the world worked together to build and analyse the most complete panel of genomes ever studied for this animal. 

 

They constructed a comprehensive genome panel containing 207 modern and 31 ancient donkeys, as well as 15 wild equids. 

 

Reporting their findings in the journal Science, the researchers reveal that the donkey was first domesticated in Africa in 7,000 years ago, around the time when the Sahara became the desert region we know today. 

 

They state that it was only 2,500 years later that donkeys left their place of origin in Africa and reached Europe and Asia, where this species developed lineages that, in some cases, still exist today. 

 

“We found a strong phylogeographic structure in modern donkeys that supports a single domestication in Africa ~5000 BCE, followed by further expansions in this continent and Eurasia and ultimately returning to Africa.”

 

By analysing archaeological remains, scientists also uncovered evidence of a previously unknown genetic lineage of donkeys that lived in the Levant, around the eastern Mediterranean, 2,000 years ago. The influence of this lineage is thought to extend far beyond the region, and still today, fragments of its genetic heritage can be found throughout Europe. 

 

The researchers suggest that these discoveries call for new archaeological digs to find the initial source of domestication in Africa, as well as the sequencing of other early donkey genomes on both shores of the Mediterranean sea, to better understand the role of this animal in the history of trade between Europe and North Africa.

 

For more details, see:

 

The genomic history and global expansion of domestic donkeys.

 

Evelyn T. Todd, Laure Tonasso-Calvière, Lorelei Chauvey, Stéphanie Schiavinato, Antoine Fages, Andaine Seguin-Orlando, Pierre Clavel, Naveed Khan, Lucía Perez Pardal, Laura Patterson Rosa, Pablo Librado, Harald Ringbauer, Marta Verdugo, John Southon, Jean-Marc Aury, Aude Perdereau, Emmanuelle Vila, Matilde Marzullo, Ornella Prato, Umberto Tecchiati, Giovanna Bagnasco Gianni, Antonio Tagliacozzo, Vincenzo Tinè, Francesca Alhaique, João Luís Cardoso, Maria João Valente, Miguel Telles Antunes, Laurent Frantz, Beth Shapiro, Daniel G. Bradley, Nicolas Boulbes, Armelle Gardeisen, Liora Kolska Horwitz, Aliye Öztan, Benjamin S. Arbuckle, Vedat Onar, Benoît Clavel, Sébastien Lepetz, Ali Akbar Vahdati, Hossein Davoudi, Azadeh Mohaseb, Marjan Mashkour, Olivier Bouchez, Cécile Donnadieu, Patrick Wincker, Samantha A. Brooks, Albano Beja-Pereira,  Dong-Dong Wu, Ludovic Orlando.

 

Science, (2022). Vol 377, Issue 6611 pp. 1172-1180

 

https://www.science.org/doi/10.1126/science.abo3503

Eriskay Ponies sought for genetic study

© Thomas Langlands | Dreamstime.com

 Eriskay pony owners are asked to take part in a genetic study to help protect this critically endangered
native breed.

The Eriskay Pony Society is working with genetics experts at Nottingham Trent University (NTU) and the Rare Breeds Survival Trust (RBST) to carry out the biggest ever survey of Eriskay Pony DNA.

 

The Eriskay is a small pony, standing 124-138cm (12.0-13.2 hands) high. Traditionally they worked on the crofts (smallholdings), carrying loads such as seaweed, and peat, in baskets (“creels”) slung over their backs. They were also used for light draught work. 

 

Eriskay ponies are among the last representatives of the original native ponies of the Western Isles of Scotland, and are probably one of the oldest and purest breeds in the United Kingdom. 

 

Their isolation on the remote island of Eriskay in the Outer Hebrides helped protect them from introduction of other breeds. On many of the Scottish islands, native ponies were “improved” by breeding with larger stallions. This did not happen on Eriskay, leaving a stock of pure-bred ponies.

 

By the early 1970’s the Eriskay Pony population had dwindled to about 20 animals. Controlled breeding programmes have restored the population to over 400 animals around the world. However, the Eriskay Pony is still classed as “critical” by the Rare Breeds Survival Trust,

 

The DNA analysis, being carried out by NTU’s Medical Technologies Innovation Facility and School of Animal, Rural and Environmental Sciences, involves Professor Philippe Wilson, Dr Samuel White and Dr Andy Dell. The work is supported by funding from the Horserace Betting Levy Board.

 

Professor Wilson explained: “We will be employing state of the art genotyping technologies in order to support a detailed understanding of the genetic status of the Eriskay and will work closely with the breed society to really deliver impact directly to the breeders.”

 

The results of the analysis will be used, in conjunction with the Rare Breed Survival Trust’s Equine Conservation project, to help inform future breeding plans and decision making for this critically endangered breed.

 

Catriona Rowan, Chair of the Eriskay Pony Society explained: “This is a very welcome step forward in our efforts to protect and promote this ancient yet versatile breed.

 

“With such a small gene pool we cannot just rely on the look of ponies and studbook information to make our breeding matches. 

 

She explained “This study, which is open to ANY Eriskay Pony registered with a recognised Eriskay breed Society, either The Eriskay Pony Society or Comann Each Nan Eilean (CENE), will give us a great foundation with which to work. It will be a baseline of information for use in our work with the RBST’s Equine Conservation Project which requires us to provide complex information about our genetic profiles. 

 

“Our work with Nottingham Trent University will give us assessment of genetic variation and molecular basis of inbreeding within the Eriskay Pony breed which will then be collated in an Eriskay Pony Genetic Archive. 

 

“It’s easy for Eriskay owners to get involved. Simply apply to us by emailing info@eriskaypony.org for a testing kit and we will send it free of charge. It’s a simple process using a hair sample, which must be returned to us by the end of July. 

 

“The more samples we have the better the overall picture we can build of the breed and the more useful the information will be. And ANY registered Eriskay Pony can make a contribution, no matter the age or breeding status, so it’s a great way for all owners to support the future of the breed.

 

For more details, or to order a free DNA kit, contact info@eriskaypony.org. Samples must be returned by the end of July.

What are omics?

Photo: Rossdales Laboratories

 You may have noticed that “-omics” are cropping up with increasing regularity. What are they, and why are they important?

Omics refers to a field of biological sciences including genomics (studying the complete genetic makeup, the DNA, of an organism), transcriptomics (studying RNA), proteomics (proteins) and metabolomics (metabolites). Omics encompasses powerful tools that are rapidly transforming our understanding of disease. 

 

To celebrate how the omics disciplines are making a significant impact on equine veterinary medicine, the Equine Veterinary Journal (EVJ) is giving free access to a Virtual Issue of recent articles covering genomics, transcriptomics, proteomics and metabolomics .

 

The virtual issue has been co-ordinated by EVJ’s Associate Editors Mandy Peffers and Pablo Murcia, with guest editors Carrie Finno, James Anderson and Macarena Sanz.

 

“The relationship between microbiota, health and disease in humans has been investigated for years but similar studies in horses have only been recently published,” says Macarena Sanz, whose editorial navigates five articles on this topic.

 

She concludes: “Although equine microbiomics is in its infancy, new studies will provide an exciting insight into the nature of the equine microbiome and its potential role in the development of disease. Knowledge of the microbiome is key to advancing prophylactic, diagnostic and therapeutic options and to better understanding the pathophysiology of equine conditions.”

 

James Anderson prefaces five papers on advances made in equine medicine within the disciplines of proteomics, metabolomics and lipidomics (a subset of metabolomics). He concludes: “Omics technologies have enhanced our knowledge of the molecular world and provided fascinating insight into the composition and functions of these components across a range of different animal species. Particularly for equine science and medicine they have increased our understanding of molecular changes in disease and informed the development of diagnostic tests. Although still in its infancy within equine veterinary science, this field looks likely to have a significant impact in the coming years.”

 

Mandy Peffers, Associate Editor of the EVJ said: “It is exciting to see how the equine veterinary sector is now keeping pace with human medicine in the omics revolution. As we continue to advance, there will be more tools at our disposal for the diagnosis and treatment of equine disease.”

 

The Virtual Issue is available to all at 

 

https://beva.onlinelibrary.wiley.com/doi/toc/10.1001/(ISSN)2042-3306.OmicsEVJ

Fragile Foal Syndrome not confined to Warmbloods

 Fragile Foal Syndrome (FFS) is a lethal genetic disease of connective tissue which has been reported most frequently
in Warmbloods. However, a recent study has found that the genetic defect responsible is present across a range of other breeds. 

Affected foals are typically aborted during late gestation or born as non-viable foals. If alive at birth, they tend to have problems such as fragile skin, skin defects, hyperextension of the joints and difficulty breathing, and generally require euthanasia within days.

 

FFS has been shown to be an autosomal recessive genetic condition. Carrier animals with one copy of the defective gene (PLOD 1 c.2032 G>A) will be normal, but if mated with another carrier may produce an affected foal.

 

It is now known that the condition is not confined to Warmblood horses.  

 

Research by Katie Martin and colleagues at Etalon diagnostics (a company that offers genetic testing), together with Dr Samantha Brooks at the University of Florida Gainesville and Dr Scott Mclure, of Midwest Equine, Iowa, found that the genetic defect occurs across other horse populations.

 

The team examined samples from 7343 horses from various breeds or type of horse.

The defective gene occurred in 5.32% of Warmblood type horses.  In other affected breeds it was less than 1%. They found no sign of the defect in Arabians, Iberian or Thoroughbreds.

 

Studies of the frequency of the defect in aborted or stillborn foals are lacking, so

the potential economic effect of FFS on the horse breeding industry is not known.

 

The researchers suggest that pre-breeding testing should be used to inform the breeding program – avoiding breeding two carriers, together to reduce the frequency of the FFS gene in the population, and reduce the number of lost pregnancies.

 

 

For more details, see:

 

Fragile Foal Syndrome (PLOD1 c.2032G>A) occurs across diverse horse populations

Katie Martin, Samantha Brooks, Micaela Vierra, W. Tyler Lafayette, Scott McClure, Meredith Carpenter and Christa Lafayette

Animal Genetics (2021) vol 52, p137.

https://doi.org/10.1111/age.13020

Genetic defect associated with painful eye condition identified

An interdisciplinary team of scientists and clinicians, led by Dr. Rebecca Bellone at the University of California Davis Veterinary Genetics Laboratory, has identified a genetic variant associated with distichiasis in Friesian horses. 

Distichiasis, is a condition affecting the eye in which aberrant hairs grow from abnormal positions along the eyelid. These hairs rub on the cornea, causing irritation and pain. Severe cases may progress to corneal ulceration, leading to vision impairment and even loss of the eye. 

 

The condition can be treated, by removing the offending hairs, for example with thermocautery. However, the condition has been reported to recur in up to 50% cases.

 

Friesians are by far the most likely breed to be affected. They are known for being relatively highly inbred and prone to a range of genetic diseases. This knowledge prompted the research team to investigate the genetic basis of the condition. 

 

For a start, researchers traced the family trees of affected horses which provided evidence of an autosomal recessive mode of inheritance. Then they conducted a Genome Wide Association Study comparing samples from 14 affected and 38 normal animals. This narrowed down the search to a section of the ECA13 chromosome.

 

Investigating the ECA13 further with Whole Genome Sequencing, they identified a large chromosome deletion between two genes that was strongly associated with distichiasis. 

 

Eighteen out of 19 affected Friesian horses were homozygous for (had two copies of) the distichiasis associated variant. This pointed to a recessive mode of inheritance.

 

However, seven out of 75 horses with no evidence of distichiasis were also homozygous for the variant. This led the research team to suggest that distichiasis in Friesians appears to be a trait with incomplete penetrance. (That is, the condition may be expressed in only some individuals that have two copies of the variant, while some homozygous individuals may never show signs of the condition.)

 

To see if the variant occurs in other breeds, they tested samples from 955 horses of 54 different breeds and identified the deletion in only 11 non-Friesians, all of which only had one copy of the variant.

 

"Given the strong association and the frequency of the variant in the population of Friesian horses we evaluated, testing for this variant can be used to avoid crosses that can produce animals homozygous for the variant," said Erin Hisey, the UC Davis veterinary student who was the first author on this study. 

 

Additionally, the results of this test can be used clinically. "Those horses that test homozygous for this variant should be evaluated for abnormal lashes to potentially provide clinical intervention prior to the development of irreversible corneal damage," said Dr. Hanneke, co-author of the study and equine surgeon with a focus in ophthalmology.

 

For more details, see:

 

Whole genome sequencing identified a 16 kilobase deletion on ECA13 associated with distichiasis in Friesian horses. 

Hisey, E.A., Hermans, H., Lounsberry, Z.T. et al. 

BMC Genomics 21, 848 (2020). 

https://doi.org/10.1186/s12864-020-07265-8

 

https://vgl.ucdavis.edu/news/vgl-led-team-identifies-genetic-variant-distichiasis-friesians