A meeting held today amongst leading equine veterinarians concluded that the MRI unit that offers a standing-and-sedated option is “crucial” to the racehorse application. The consensus was that standing MRI is clearly already valuable as a clinical tool to aid diagnosis and case management, and it offers experienced veterinarians a unique tool to aid clinical and training decisions via serial examinations on the same horse. As a routine screening tool, the group said it had the “best potential” to screen racehorses at risk for condylar fracture, the leading cause of fatal breakdowns on the track.
The meeting, hosted by Hallmarq Veterinary Imaging, was convened to discuss the potential for standing MRI to be used as a screening tool to reduce the risk of catastrophic fracture on the racetrack or in training. Four speakers presented, from the United States, the United Kingdom, and Canada.
Introducing the meeting, Dr. Scott Palmer DVM (New Jersey Equine Clinic, Millstone Twp, NJ) summarized the importance of reducing racetrack fatalities. He pointed out how all other techniques have failed to meet the critical criteria: that they must be affordable, accurate, and repeatable by avoiding general anesthesia. Standing MRI now appears to offer the best opportunity, especially given that over 90% of fatal injuries relate to the distal metacarpal area. The group’s questions focused on the affordability aspect, with Alan Ruggles DVM, of Rood and Riddle, asking “what is a fair price?” In the ensuing discussion, it was determined that pricing for racehorses screening could likely fall to a level that be considered affordable by trainers.
Dr. Sarah Powell MRCVS (Rossdale and Partners, Newmarket, UK ) presented her clinic’s significant experience with MRI in two presentations. Located in an area home to some 5,000 horses, Rossdales has performed approximately 2,800 MRI scans over the past five years, primarily of sport horse feet and racehorse fetlocks.
Dr. Powell started off citing published[i] evidence showing how low- and high-field MRI produce images of the fetlock that are close in diagnostic capability, especially for bone pathology. She then illustrated the underlying capability of the Hallmarq MRI by showing images obtained under general anesthesia, and pointed out recent advances in the STIR and T2 FSE sequences. Dr. Powell concluded with emphasis, “If you are not routinely collecting acceptable images with this scanner, the room and procedures should examined and corrected.”
Moving on to clinical observations, Dr. Powell described some of the top issues regarding pathologies seen in the Thoroughbred racehorse fetlock, such as bone mineral densification, vascular patterns over-diagnosed as partial fractures, and differentiation of palmar/plantar osteochondral disease (POD) and parasagittal fissures, which present in a similar clinical manner. Other pathologies she illustrated included P1 injuries, cartilage erosions and dorsal joint disease.
In questions, Dr. Ruggles asked if all these images were collected with motion correction, and which sequences were best for cartilage. Dr. Powell replied, “In many cases, the horse stands sufficiently still so that standard, or even high, resolution sequences are preferable.”
Dr. Powell’s second presentation explained how MRI fits into the integrated clinical examination, “The relationship with trainers is variable, but the best yards allow frequent reviews of horses that are not performing well. If the trainer or rider notices a problem in the morning, the veterinarian will examine the horse in the afternoon and if necessary refer it to the clinic for further examination the following day.”
The UK is at a different stage of MRI usage than the USA. Dr. Powell explained, “Trainers around the world are, by nature, wary, with a focus on the cost of MRI versus improved outcomes. Yet, unlike in the United States, racing is expanding in the United Kingdom through increasing appeal to families, which makes it even more important to prevent public catastrophes and educate trainers that fractures may not be just an "unlucky step" but may relate to previous training history. At the introduction of MRI into the UK market, considerable effort was put into education evenings and the presentation of facts, photos and represented scientific research from both the equine and human sports medicine communities.”
Dr. Powell said that with definitive answers available from MRI, benefits to trainers include:
· Helps long term planning of a racing campaign for each horse.
· Keeps the horse in training (possibly with a modified program), satisfying owners and trainers.
· Avoiding anesthesia makes it safe with minimal time out.
· Helps make decisions with regard to planned long distance travel.
· Helps decide whether to wrap up a horse for the remainder of the year.
· Helps assess new horses on the yard.
Dr. Powell finished the presentation with specific case management examples, saying, “For racehorse vets, MRI is particularly useful when other techniques fail to reach a clear conclusion: to confirm or rule out lesions, identify fractures or other pathology not visible on x-ray, and distinguish between potential alternative diagnoses.”
Dr. Tim Parkin MRCVS (Senior Research Fellow, Glasgow, UK) also made two presentations. In the first he described a study[ii] that investigated the observable markers that might distinguish horses at risk of lateral condylar fracture, which concluded positive correlation with:
· Lack of fast work in training.
· Horses in the first year of training.
· Horses which first race at 3 or 4 years of age.
· Races over longer distances, with larger numbers of starters, and with an amateur jockey.
· Firmer ground.
· Pre-existing pathology in the parasagittal grooves.
A number of MRI observations were also seen more frequently in fractured limbs, or in the contralateral limb of fracture cases, compared to fatalities unrelated to bone fracture. However, Dr Parkin went on to explain that this study was in a pre-selected population in which 50% of the legs examined were from fracture cases, while in the postulated screening application the number of horses expected to be at risk of fracture would be much lower. This increases the probability of a false positive test, concluding that for reliable screening MRI would need to be combined with some other test which can exclude some horses definitely not at risk, perhaps based on blood markers, genetic tests, or the risk factors identified above.
The final presentation was by Dr. Tom Wilkinson DVM (Moore and Co, Calgary, Canada). During his residency at Washington State University under the supervision of Dr Russ Tucker, Dr Wilkinson examined cadaver limbs of a large number of racecourse fatality cases by high field MRI using a large selection of pulse sequences. Sagittal images from one of these (Proton Density Spin Echo, PD SE) are visually similar to the T1W GRE images used for the previous presentation, and also show a variable region of hypointensity in the condyle.
As the meeting concluded, a frequent comment heard was how unusual and valuable it was to get so many of the nation’s leading Thoroughbred racehorse veterinarians in one room. Future meetings are in the planning stages to further the discussion and studies of how reduce Thoroughbred racehorse breakdowns.
For more information about Hallmarq standing MRIs, please visit hallmarq.net, or call 978-266-1219.
About Hallmarq Veterinary Imaging
As the sole global manufacturer of MRI systems for the standing sedated equine and with over 20,000 anesthesia-free exams on record, Hallmarq Veterinary Imaging is the pioneer of safer MRI diagnostics. The team behind its development have decades of experience in the design and manufacture of clinical, research and industrial MRI systems for a range of applications globally. From its beginnings over 10 years ago, Hallmarq’s mission has been to make equine MRI safe, accurate and cost effective for horse owners, and affordable and profitable to key equine veterinary clinics worldwide.