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

Reconstructing prehistory from a teaspoonful of soil

Yukon Photo credit Tyler Murchie

Prehistoric horses survived longer in North America than previously thought, according to a new study.

Researchers at McMaster University, Hamilton, Canada, used DNA capture-enrichment techniques, that they had developed previously, to find ancient DNA from plants and animals in as little as a teaspoonful of soil. The soil for the study was taken from core samples collected from the permafrost at four sites in the Klondike region of central Yukon, in northwest Canada. 

 

The work is published in the journal Nature Communications.

 

Tyler J. Murchie  and co-authors explain that environmental samples, such as soil, contain fragments of genetic material. Most ancient environmental DNA (eDNA) is broken down by bacteria or by physical or chemical processes. However, some of this eDNA becomes bound to sedimentary minerals, which protects it, especially when it is frozen. 

 

By extracting and analysing this sedimentary ancient DNA (sedaDNA), the research team was able to build up a picture of the plant and animal ecosystems from 30,000 to 4000 years ago. 

 

By analysing the DNA, the research team could rebuild the fluctuating animal and plant communities at different time points. Of particular interest was the Pleistocene-Holocene transition, an unstable climatic period 11,000-14,000 years ago when a number of large species such as mammoths, mastodons and sabre-toothed cats disappeared.

The analysis reveals that mammoths and horses were already in steep decline prior to the climatic instability, but they did not immediately disappear due to human overhunting as previously thought. In fact, the DNA evidence shows that both the woolly mammoth and North American horse persisted until as recently as 5,000 years ago.

The authors explain that through the early Holocene (starting about 11,000 years ago), the Yukon environment continued to experience massive change. Formerly rich grasslands - the “Mammoth Steppe”- were overrun with shrubs and mosses, species no longer held in check by large grazing herds of mammoths, horses and bison. Today, grasslands do not prosper in northern North America, in part because there are no megafaunal “ecological engineers” to manage them. 

“The rich data provides a unique window into the population dynamics of megafauna and nuances the discussion around their extinction through more subtle reconstructions of past ecosystems” says evolutionary geneticist Hendrik Poinar, a lead author on the paper and director of the McMaster Ancient DNA Centre.

This work builds on previous research by McMaster scientists who had determined woolly mammoths and the North American horse were likely present in the Yukon approximately 9,700 years ago. Better techniques and further investigation have since refined the earlier analysis and pushed forward the date even closer to contemporary time. 

“Now that we have these technologies, we realize how much life-history information is stored in permafrost,” explains Tyler Murchie, a postdoctoral researcher in McMaster’s Department of Anthropology and a lead author of the study.

“The amount of genetic data in permafrost is quite enormous and really allows for a scale of ecosystem and evolutionary reconstruction that is unparalleled with other methods to date” he says.

“Although mammoths are gone forever, horses are not” says Ross MacPhee of the American Museum of Natural History, another co-author. “The horse that lived in the Yukon 5,000 years ago is directly related to the horse species we have today, Equus caballus. Biologically, this makes the horse a native North American mammal, and it should be treated as such.” 

Scientists also stress the need to gather and archive more permafrost samples, which are at risk of being lost forever as the Arctic warms.

 

For more details, see:

 

Collapse of the mammoth-steppe in central Yukon as revealed by ancient environmental DNA

Tyler J. Murchie, Alistair J. Monteath, Matthew E. Mahony, George S. Long, Scott Cocker, Tara Sadoway, Emil Karpinski, Grant Zazula, Ross D. E. MacPhee, Duane Froese & Hendrik N. Poinar 

Nature Communications (2021) vol 12, Article number: 7120 

 

https://doi.org/10.1038/s41467-021-27439-6

 

For a video presentation, see:

https://player.vimeo.com/video/654303546

A cheaper alternative for URT scoping

Is there a cheaper alternative to the traditional endoscopes used for examination of the upper respiratory tract (URT) of horses?

Flexible endoscopes have proved invaluable for inspecting the inner workings of the equine respiratory system for over 40 years. The equipment is expensive and so is not always readily available. 

 

Borescopes are commonly used in industry for tasks such as the inspecting the inside of engines and other confined spaces.  A wide variety of types are available, most considerably less expensive than medical grade endoscopes. 

 

Researchers in the Faculty of Veterinary Medicine, Ghent University, investigated the suitability of a flexible and steerable borescope connected to a smartphone for examining upper respiratory tract problems in horses. Zoe Neuchermans and her colleagues in the department of Large Animal Internal Medicine conducted a study involving a series of clinical cases. Horses were inspected first with a flexible borescope and then with the standard flexible endoscope.

 

They made digital recordings of upper respiratory tract including structures of interest (depending on the clinical case). These were later reviewed by an observer who did not know which device had been used to make the recording. The work was presented at the British Equine Veterinary Association Congress 2021 and has been published in the Equine Veterinary Journal.

 

The authors report that “borescope and endoscope grading scores for pharyngeal lymphoid hyperplasia, recurrent laryngeal neuropathy and tracheal mucus were identical in 88/100, 93/100 and 48/59 horses, respectively. The remainder differed only one (sub)grade.”

 

The only problem they reported was that they had to replace the borescope after about 45 examinations as the steering mechanism started to fail ,which limited the field of view.

 

Although their study was limited to only one of the many types of borescope available, the researchers came to the conclusion that a flexible, steerable borescope, connected to a smartphone, provides a cheap alternative to perform URT endoscopy in horses.

 

For more details, see: 

 

Diagnosis of upper respiratory tract disorders in horses using a cheap, flexible and steerable borescope

Z. Neuckermans; E. Paulussen; L.-M. Verhaeghe and G. van Loon.

Equine Vet J (2001) Vol 53, S55, p22-23

 https://doi.org/10.1111/evj.33_13492

Fungal changes in gut of horses with grass sickness

Horses with Grass Sickness have differences in the population of fungi (“mycobiota”) present within in the gut
compared with healthy horses, a recent study has revealed.

Equine grass sickness (EGS, also known as equine dysautonomia) damages the autonomic nervous system – the part of the horse’s nervous system that controls involuntary functions. Its effects are particularly apparent in the gastro-intestinal tract. Clinical signs range from depression, with difficulty eating and swallowing, to reflux of stomach contents, weight loss and death. 

The exact cause is unknown, but researchers now know a lot about risk factors to be avoided and believe that a type of toxin is involved.  Is EGS is associated with ingestion of mycotoxin-producing fungi? 

Researchers, led by Bruce McGorum at the University of Edinburgh, conducted a study to identify potential causal fungi. They analysed the mycobiota within the gut contents of horses with grass sickness and compared their findings with samples taken from horses that died from reasons other than gastro-intestinal or neurological problems. They also analysed faecal samples from unaffected horses grazing the same pasture as horses with grass sickness.

They found a very rich and diverse gastro-intestinal mycobiota in all the horses. The mycobiota appeared to be richer (ie containing more different types of fungi) and more diverse (a more even distribution of the types of organism) in grazing horses. Mycobiota richness was greater in horses with EGS. 

 

The research team identified 56 key “phylotypes” that were more common in EGS samples. Many of these key phylotypes were extremophiles (organisms able to survive in extreme environments) or were considered likely to produce extrolites (secreted metabolites) that might have toxic effects.

These changes in the mycobiota have not been shown to cause EGS. Further work is needed to determine whether neurotoxic extrolites from these key phylotypes play a role in causing grass sickness.

 

For more details, see:

Equine grass sickness (a multiple systems neuropathy) is associated with alterations in the gastrointestinal mycobiome

Bruce C. McGorum, Zihao Chen, Laura Glendinning, Hyun S. Gweon, Luanne Hunt, Alasdair Ivens, John A. Keen, R. Scott Pirie, Joanne Taylor, Toby Wilkinson & Gerry McLachlan 

Animal Microbiome (2021) vol 3, Article number: 70 

https://doi.org/10.1186/s42523-021-00131-2

Search for a test to predict horses at risk of catastrophic injuries

In the ongoing quest to make racing safer for horses, researchers have been looking for a blood test to identify horses at risk of catastrophic fractures.

Other than sudden high energy trauma resulting from falls in jump racing, most racing fractures are thought to be fatigue injuries which result from cumulative stresses and strains.

 

Advanced imaging techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) scans, have been used to identify damage that might lead to catastrophic fractures. However, such methods would be too expensive and impractical for routine use.

 

Most catastrophic fractures are found to have underlying pre-existing damage. The associated inflammation results in changes in the activity of various components of the inflammatory process, So checking for inflammatory markers might give warning of potential risk.

 

Dr Allen Page and colleagues at the University of Kentucky’s Maxwell H Gluck Equine Research Center, hypothesised that analysis of messenger RNA expression would detect significant changes in horses at risk for a catastrophic injury.

 

Their study involved blood samples collected from Thoroughbred horses in five racing jurisdictions across the United States. The work is published in the Equine Veterinary Journal.

 

They looked at 21 genes potentially associated with bone inflammation and remodelling,  and compared the levels of gene expression in horses that had suffered a catastrophic fracture with those in horses that had raced without injury.

 

Three markers, - insulin like growth factor 1 (IGF-1), matrix metalloproteinase 2 (MMP 2) and IL-1 receptor antagonist (IL1RN) - showed a marked difference between injured and non-injured horses. The researchers found that together, the three markers correctly identified horses at risk of catastrophic injury 76% of the time (and correctly excluded horses from being at risk 88% of the time)

 

They conclude that “Analysis of mRNA expression of specific genes in the future may be considered as an economical, accessible and non-invasive means by which horses at risk for catastrophic injury can be identified.”

For mor details, see:

Expression of select mRNA in Thoroughbreds with catastrophic racing injuries.
Page AE, Adam E, Arthur R, Barker V, Franklin F, Friedman R, Grande T, Hardy M, Howard B, Partridge E, Rutledge M, Scollay M, Stewart JC, Vale A, Horohov DW.
Equine Vet J. 2022; vol 54(1) pp63-73. 

https://doi.org/10.1111/evj.13423