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.