48
46TH
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SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
available pre-operatively, it is generally thought of as a great advantage for surgical
planning.
Diagnostic Imaging – Magnetic Resonance Imaging
Magnetic resonance imaging is very useful for evaluation of the fetlock joint. This
technique has the ability to evaluate all of the important components of the joint.
MRI even provides physiologic information through the utilisation of fluid sensitive
sequences that can identify bone contusions or edema. The only notable exception
may be articular cartilage; in the fetlock articular cartilage is thin and covers a curving
surface, making it problematic to image on all modalities but also on MRI. Cartilage
imaging continues to improve with new sequence development.
In the fetlock region, the debate over high (>1.0Tesla) versus low field (<1.0Tesla)
strength MRI continues. The debate centres on cartilage, subchondral bone and
small soft tissue structure imaging. In higher field strength magnets, cartilage and
small parts are imaged better. Furthermore, higher fields strength magnets generally
have more sophisticated means of producing high detail bone imaging and have more
options for fluid sensitive sequences. Low field magnets provide very useful
information but to lesser degree of detail. Standing low field MRI provides very good
information but in this anatomic region, image quality can be greatly degraded by
patient motion. It remains however that standing low-field MRI obviates the need
for general anesthesia and is largely considered to be more practical particularly in
competition horses.
Summary
Fetlock imaging is an important component of lameness diagnosis in the horse. In
many cases, radiography and ultrasonography should be considered complementary
for complete evaluation of the functional unit. Other diagnostics including nuclear
scintigraphy, computed tomography and magnetic resonance imaging have important
merits. In the fetlock the identification of injury early in the disease process is
important to aid in early, directed treatment and for the possible prevention of
stress remodeling related breakdown injuries.
References
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Kane AJ, McIlwr aith CW, Park RD, et al. Radiographic changes in Thoroughbred yearlings.
Part 2: Associations with racing performance. Equine Vet J 2003;35:366-374.
Preston SA, Trumble TN, Zimmel DN, et al. Lameness, athletic performance, and financial
returns in yearling Thoroughbreds bought for the purpose of resale for profit. J Am Vet Med
Assoc 2008;232:85-90.
Meagher DM, Labadie JD, Meagher DT, et al. Radiographic Abnormalities of Thoroughbred
Horses in 2-year-old In-Training Sales and Associations with Race Performance. Annual
Convention of the American Association of Equine Practitioners 2010;403-404.
Estberg L, Stover SM, Gardner IA, et al. Fatal musculoskeletal injuries incurred during racing
and training in thoroughbreds. J Am Vet Med Assoc 1996;208:92-96.
Johnson BJ, Stover SM, Daft BM, et al. Causes of death in racehorses over a 2 year period.
Equine Vet J 1994;26:327-330.
Butler JA, Colles C, Dyson S, et al. Clinical Radiology of the Horse: Wiley-Blackwell, 2008.
O'Brien TR. Radiographic Interpretation of the Fetlock. O'Brien's Radiology for the Ambulatory
Equine Practitioner. Jackson, WY: Teton NewMedia, 2005;129-168.
Ross MW, Dyson SJ. Diagnosis and Management of Lameness in the Horse: Elsevier - Health
Sciences Division, 2010.
O'Brien TR, Hornof WJ, Meagher DM. Radiographic detection and characterization of palmar
lesions in the equine fetlock joint. J Am Vet Med Assoc 1981;178:231-237.
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