As a lay person, it’s easy to think that a bone scan is one of the best diagnostic tools available, a gold standard in diagnosing what’s wrong with our horse. This study looked at how effective the bone scan is, by looking at how well bone scan results matched with final diagnoses. The authors included all sports horses who had a bone scan between March 2008 and December 2014 who had ultimately received a specific diagnosis. This totalled 480 horses, with a total of 1222 clinical diagnoses (i.e. many of the horses had more than one thing wrong). Of these 1222 diagnosis, over half (56.4%) did not show as relevant on the bone scan (i.e. there was no increased radiopharmaceutical uptake). 8% showed increased uptake on the bone scan which was not relevant in the horse’s diagnosis. There was better agreement between the results of the bone scan and the final diagnosis if the relevant area was the feet, or the top of the front leg (elbow, shoulder and shoulder blade). The conclusion was that a bone scan should not be used as an indiscriminate diagnostic tool, and on it’s own it’s unlikely to lead to a diagnosis in the case of lameness or poor performance.
Quiney, Laura & Ireland, Jo & Dyson, Sue. (2018). Evaluation of the diagnostic accuracy of skeletal scintigraphy in lame and poorly performing sports horses. Veterinary Radiology & Ultrasound. 59. 10.1111/vru.12626
You can access the full article here.
Skeletal scintigraphy is an established imaging modality, however, its validity as a diagnostic test in lame or poorly performing sports horses has not been determined. The objective of this retrospective cross-sectional analytical study was to determine the accuracy of skeletal scintigraphy as an indiscriminate screening test in sports horses. All sports horses that underwent scintigraphic examination between March 2008 and December 2014 for which a definitive diagnosis was reached were included. Examinations were evaluated blindly. Characteristics of increased radiopharmaceutical uptake were recorded and subjectively categorized as possibly relevant or non-relevant. Kappa statistics were used to assess agreement between test results and final diagnosis. There were 1222 positive clinical diagnoses in 480 horses, of which 687 regions (56.4%) had no associated increased radiopharmaceutical uptake and 99 regions (8.1%) had non-relevant increased radiopharmaceutical uptake. The sensitivity of increased radiopharmaceutical uptake for identification of final diagnosis was low (43.8%) and specificity was high (94.0%). The agreement was fair (κ = 0.36). Relevance categorization improved the test; the sensitivity for final diagnosis was low (35.7%), specificity was high (98.9%), and the agreement was moderate (κ = 0.45). The agreements of increased radiopharmaceutical uptake and relevance categorization with final diagnosis were only substantial for feet (κ = 0.67 and κ = 0.66, respectively) and proximal aspect of the forelimb (elbow, shoulder, and scapula combined) (κ = 0.69 and 0.78, respectively). Scintigraphic examination is unlikely to lead to a full and correct diagnosis of the cause(s) of lameness or poor performance in sports horses when used as an isolated or indiscriminate screening tool.
© Sue Palmer, The Horse Physio 2021
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