COMPARISON OF PLAIN RADIOGRAPHY AND COMPUTED TOMOGRAPHY FOR DETECTION OF ELBOW DYSPLASIA IN LABRADOR RETRIEVER

To our knowledge there has been no comprehensive direct comparison between the plain radiology and computed tomography (CT) for diagnosis of elbow dysplasia through the use of a grading score. The first aim of the study was to clinically apply a comparative grid (proposed at the last IEWG meeting in 2016) to grade elbow dysplasia on CT similarly as is done on traditional radiology. The second objective was to evaluate the concordance of the grading between the two imaging modalities at the age less than 12 months and over 12 months and to emphasise the differences observed between puppies and adult dogs. Thirty-nine (39) Labrador Retriever (78 elbow joints) were included in the study, the dogs were own client dogs, asymptomatic, no one showed any sign of lameness nor other clinical problems. At the age <12 months the agreement between plain radiology grading and CT grading was fair (K 0.33), the sensitivity of radiography to identify elbow dysplasia was 75% and specificity 100% (P<0.001). At the age >12months the agreement was fair too with K 0.23 and the sensitivity was 70% and specificity 98% (P<0.001). A development of the disease has been noted between the evaluations at different ages. On plain radiography the grade of disease worsened in 24 elbow joint and improved in 2 (P 0.001). On CT the grade of the disease remained invariable in 54 joints and showed a worse grade in 19 joints and improved in 5 joints (P 0.004). Further studies including also other breeds might provide more information about the accurate use of a score grading on CT. The presence of false-negatives in our group of dogs and the fair agreement between the two modalities open a discussion about the exclusive use of radiographs in the screening program. As well a screening program to treat dogs at too young an age should be reassessed having regard to the disease progression, which, however is not related to any clinical symptoms.