Ultrasonographic detection of joint lesions in canine leishmaniasis caused by Leishmania infantum.

Canine leishmaniasis (CanL), caused by Leishmania infantum, is a multisystemic disease with substantial musculoskeletal involvement. We aimed to assess the usefulness of USG in diagnosing joint abnormalities in dogs with CanL using a clinical approach. Forty-three L. infantum PCR-positive dogs underwent comparative orthopedic physical examination and joint USG; 20 (20/43) also underwent radiography. Tarsal joints were systematically imaged, whereas other joints were imaged if they showed orthopedic clinical signs. Tarsal lesions were detected by joint USG in 86% (37/43) of the dogs, with osteophytes (83.8%), joint effusion (64.9%), and capsular thickening (59.4%) being the most frequent. Radiography detected tarsal lesions in 40% (8/20) of the dogs. As a definitive gold-standard procedure was not available, physical orthopedic examination served as the reference to assess method sensitivity for detecting joint alterations; USG demonstrated 89.7% sensitivity, whereas radiography demonstrated 46.7%. Overall, 86% (37/43) of the dogs had ultrasonographic joint alterations consistent with degenerative processes associated with chronic inflammation. In selected cases, synovial fluid cytology revealed Leishmania amastigotes, and histopathologic findings confirmed the severe inflammatory nature of the lesions, demonstrating synovial membrane thickening and lymphoplasmacytic infiltrates. Among dogs with joint lesions detected by USG, 29.7% (11/37) had no clinical orthopedic signs, underscoring USG's potential to detect subclinical joint involvement. Using this hitherto inedited approach, we conclude that USG outperformed radiography in detecting arthropathy in CanL, including cases without overt clinical signs of joint alteration. This supports recommending joint USG as a first-line procedure for the early diagnosis of arthropathy in dogs with L. infantum infection.