The number of imaging technologies available for evaluating lameness has increased in recent years. While routine radiography is not the ideal diagnostic technique to detect musculoskeletal diseases, it remains the most available and used diagnostic imaging technique for the evaluation of most bone lesions that cause lameness in small animals. Alternate imaging modalities are less frequently used, but CT and MRI are emerging for veterinary use. In this lecture, traumatic etiologies will not be covered.
Juvenile Joint Diseases
Clinical data including history, signalment e.g., gender, size and breed, type of food and activity level help to narrow the differential diagnosis list. Also, clinical signs and findings of the orthopedic examination are the criteria used by clinicians to establish probable causes (diseases) to be investigated by the radiographic exam. Traditionally, radiology technicians and radiologists select the most adequate positioning and radiographic views for a particular lame young dog according to the clinicians' suspected disease(s). In our radiology service we used to include some extra views looking for conditions that were not mentioned on the clinical request but would fit the breed, age and that might have passed unnoticed during the orthopedic examination. This does not mean that we trust the clinicians' judgment, but we do know that many young dogs are so excited or stressed while being examined and palpated that they may hide relevant signs and/or show unreal pain or discomfort misleading the interpretation of the orthopedic examination. We propose a routine radiographic exam protocol for young growing dogs with non-traumatic lameness that covers the most likely and common developmental diseases of the thoracic and pelvic limbs. A total of 9 views are made. We choose the side (right or left limb) by the clinical signs, but sometimes we take extra views of the contralateral limb. Even when the main complaint involves one of the thoracic limbs, we do the extended VD for hip dysplasia and the stifles.
Large and large breed dogs are submitted to radiographic exam under general anesthesia (propofol) in the following views and sequence:
Thoracic Limb (Six Views)
Shoulder joint: Mediolateral
Osteochondrosis / OCD
Elbow joint: Craniocaudal /lateral/flexed lateral
Ununited anconeal process
Fragmented medial coronoid process*
Osteochondrosis of the humeral condyle
Distal radio / ulna: Craniocaudal
Retained cartilage core of the distal ulna
* Cannot be ruled out by radiographic exam alone. CT is more sensitive.
** Contralateral limb films may be necessary
Editor Note: Second note above (**) doesn't have a corresponding match in the text
Pelvic Limb (Three Views)
Hips: Extended VD
Osteochondrosis of the stifle
Lateral patellar luxation
Distal tibia: Craniocaudal
Osteochondrosis of the talus
Small or small and toy breeds dogs are submitted to radiographic exam under general anesthesia (propofol) in the following views and sequence:
Mediolateral and craniocaudal of the entire limb looking for unnoticed trauma.
Extended VD of both entire legs
Avascular necrosis of the femoral head
Medial patellar luxation
Geriatric Joint Disease
The most common cause of lameness in geriatric dogs is primary or secondary degenerative joint disease (DJD). History and orthopedic exam findings help the clinician to localize the probable cause to the axial or appendicular skeleton. Laboratory tests may rule in or out infectious and immune mediated etiologies (polyarthritis). The thoracic limbs are more frequently affected by shoulder and elbow DJD while pelvic limbs are more frequently affected by hip and stifle DJD. Radiographic examination should be oriented by the orthopedic exam findings.
Degenerative Joint Disease (DJD)
DJD, osteoarthritis and osteoarthrosis are terms used to summarize radiographic changes involving a joint but are generic with regard to etiology. Primary DJD is a condition whereby no inciting factor can be established and the etiology is not determined. This is seen as an age-related change in the shoulder joints of dogs. Secondary DJD is a condition whereby an inciting etiology is present, such as elbow or hip dysplasia.
DJD secondary to osteochondrosis
Shoulder luxation (old poodles and shelties)
Mineralization of the supraspinatus tendon
DJD secondary to elbow dysplasia
Hip: DJD secondary to hip dysplasia
Secondary to osteochondrosis of the femur
Cruciate ligament damage
Shoulder conditions are increasingly common. Radiographic signs may be absent (normal exam) or only shows soft tissue mineralization and signs of DJD. Many causes of shoulder lameness have perhaps been attributed to sprains or strains but are now, with the availability of advanced imaging techniques, being more accurately identified.
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