Experts in mathematics, physics, stem-cell biology and equine medicine have joined forces in ground-breaking research to shed new light on damaging hoof diseases.
The research reveals new evidence on the mechano-biology of the hoof and related diseases.
The findings challenge traditional perceptions that the amount of weight being borne by the feet is necessarily a significant risk factor.
The study, published in the Journal of the Royal Society Interface, could lead to better diagnosis and treatment of hoof disease in the future.
Many elements of hoof development and growth are not fully understood. The hoof is not static but grows continuously over time.
How the growth of a hoof responds to the physical environment has not received any adequate answers, the study team said.
As a result, several questions remain, such as how the growth rate of the hoof capsule can be approximately 0.1mm a day when keratinocyte cells proliferate at a typical rate of about 0.01mm a day?
It also remains unclear how a strong hoof capsule can emerge from soft keratinocyte tissues where single cells have far less elastic strength.
Also, what are the biological mechanisms promoting the growth stress to allow the hoof to be a weight-bearing element and how do these mechanisms impact the future shape of the hoof? And, to what extent is physics involved and can explain hoof deformities?
To look at these questions, a multidisciplinary approach was needed.
The team of experts analysed the hooves of horses using cutting-edge three-dimensional Synchrotron imaging techniques, took samples for microscopic examination and used stem-cell biology.
They also carried out a field study of 129 horses to provide the most detailed picture of the structure, biology and physical dynamics of the hoof ever produced.
The results show where the stress in hoof growth originates; why the hoof growth rate is higher than the proliferation rate of epithelial cells and how the soft-to-hard transformation of the epithelium allows the hoof to continually bear weight.
They also showed how hoof misshaping over time is linked to the asymmetrical design of the equids’ feet, coupled with an inability of the biological growth stress to compensate for this asymmetry.
The findings provide fresh clues about the causes and potential treatment of specific hoof diseases. This includes the “Aladdin’s slipper” conformation of the hoof and the potential onset of laminitis, linked to more than 7% of equine deaths worldwide.
Hoof pathologies are an ancient problem in horses, mules, and donkeys. Aristotle wrote on the subject around 350BC and the condition has confounded horse owners and veterinary surgeons to this day.
With 110 million working equids helping 600 million people in developing countries, understanding the pathologies of the hoof is crucial for better prevention and management of the condition.
“Our study could have huge implications for the prevention and management of chronic hoof pathologies and deformities in the future in developing countries but also in economically advanced countries where horses are considered as pets,” said the University of Nottingham’s Dr Cyril Rauch, who led the work.
Rauch, an Associate Professor in Physical and Mathematical Veterinary Medicine and Science, says the work provides a strong base to develop theoretical models for farrier work. “Strong scientific evidence is really what is needed in this field.”
The work also opens a new window to understand the connection between chronic and acute hoof pathologies, he says.
“We have shown a number of things that we want to push forward. The first one is that there is a need to further develop the interaction between scientific and medical fields whatever their origins to allow the ‘Physics of Animal Health’ to be fully established.
“Secondly, equids are considered as pets in economically developed countries but in developing countries they are very often the only source of income for their owners.”
This, he says, is why the researchers are working the charities Spana and Brooke, which operate in developing countries to promote the health and welfare of working equids.
Scientists have already travelled to Ethiopia to assess hoof pathologies in working equids to evidence how their work can change the lives of horse owners.
Research collaborator Professor Patricia Harris, head of the Equine Studies Group at the Waltham Centre for Pet Nutrition, describes the study findings as interesting.
“While we know that obesity may increase the risk of laminitis, we also know that laminitis can affect lean animals, usually those with insulin dysregulation.
“Genetics obviously has a role to play but the conundrum remains that some horses with one or more predispositions do not get laminitis while others do, and this is why the study is so interesting; it provides an alternative angle to consider rather than insulin per se or obesity per se.”
Dr Nicola Menzies-Gow, a reader in equine medicine at the Royal Veterinary College, said the collaborative research has combined the expertise of scientists from a wide range of disciplines to focus on a novel angle with respect to a very challenging disease.
“The findings provide the basis for further research with respect to laminitis and other chronic hoof pathologies. We are excited to see where this may lead.”
The work was funded by PetPlan Charitable Trust, Waltham and The Ministry of Higher Education and Scientific Research of Iraq.
Collaborators include researchers from the Royal Veterinary College, the Waltham Centre for Pet Nutrition, Diamond Light Source in Oxfordshire, and the College of Veterinary Medicine at the University of Dyala in Iraq.
Physics of animal health: on the mechano-biology of hoof growth and form
Ramzi Al-Agele, Emily Paul, Sophie Taylor, Charlotte Watson, Craig Sturrock, Michael Drakopoulos, Robert C. Atwood, Catrin S. Rutland, Nicola Menzies-Gow, Edd Knowles, Jonathan Elliott, Patricia Harris and Cyril Rauch.
Journal of the Royal Society Interface, published: 26 June, 2019. https://doi.org/10.1098/rsif.2019.0214