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

 Humerus: Mediolateral

 Panosteitis

 Elbow joint: Craniocaudal /lateral/flexed lateral

 Elbow dysplasia

 Incongruent joint

 Ununited anconeal process

 Fragmented medial coronoid process*

 Osteochondrosis of the humeral condyle

 Distal radio / ulna: Craniocaudal

 Hypertrophic osteodystrophy

 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

 Hip dysplasia

 Stifle: Craniocaudal

 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:

Thoracic Limb

 Mediolateral and craniocaudal of the entire limb looking for unnoticed trauma.

Pelvic Limb

 Extended VD of both entire legs

 Avascular necrosis of the femoral head

 Hip dysplasia

 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.

Thoracic Limb

 Shoulder

 DJD secondary to osteochondrosis

 Shoulder luxation (old poodles and shelties)

 Calcifying tendinopathy

 Bicipital tenosynovitis

 Mineralization of the supraspinatus tendon

 Elbow

 DJD secondary to elbow dysplasia

 Synovial sarcoma

Pelvic Limb

 Hip: DJD secondary to hip dysplasia

 Stifle

 Secondary to osteochondrosis of the femur

 Patellar luxation

 Synovial sarcoma

 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.

References

1.  Wisner ER, Konde LJ. In: Thrall, DE Textbook of Veterinary Diagnostic Radiology 4th edition. 2002. p.146.

2.  Graeme A. In: Thrall, DE Textbook of Veterinary Diagnostic Radiology 4th edition. 2002. p. 187

3.  Dennis R, et al. Handbook of small animal radiological differential diagnosis. 2001. p.39

4.  Nieves MA. Proceedings of the Western Veterinary Conference 2006.

5.  Rochat MC. Proceedings of the Western Veterinary Conference 2008.

6.  Lewis DD, et al. Comp on Cont Ed. 14; p.287. 1992.