1 year 3 month old female neutered Podenco Ibicenco
This dog was presented with 5/10th lameness on the left fore leg for 5 days since playing roughly with other dogs. She was often non-weight bearing when standing and no improvement was seen on meloxicam. A hard swelling on the dorsal aspect of the left carpus was palpated with crepitus in the joint and was none painful. She has a history of travelling to Spain.
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LEFT CARPUS: Centered on the dorsodistomedial aspect of the left radius, there is a focal region of cortical lysis with ill-defined margins and a broad zone of transition. Additionally, ill-defined periosteal reaction is also seen along the dorsal aspect of the distal radius. Along the medial aspect of the distal radius, smooth, well-defined periosteal reaction is noted, which abruptly becomes more ill-defined distally. Circumferentially the soft tissues of the distal antebrachium are thickened, more pronounced along the dorsal, medial, and lateral aspects. The antebrachiocarpal joint is within normal limits. The middle carpal joint and carpometacarpal joint are also unremarkable.
Fig. 1. Craniocaudal and lateral projections of the distal left antebrachium showing the regions of lysis (green arrows) and abnormal periosteal reaction (red arrow).
RIGHT CARPUS: No abnormalities are noted.
1. Aggressive osteolytic and osteoproliferative lesion centered on the left distal radial metaphysis. Differentials include primary osseous neoplasia such as osteosarcoma, or osteomyelitis associated with bacterial or fungal infection.
2. Normal limited study of the right carpus.
Osteosarcoma has a bimodal age distribution resulting in peak incidence in young dogs that are approximately 2 years of age as well as older dogs that are approximately 6-8 years of age. Therefore, it is possible that this aggressive lesion centered on the distal radial metaphysis, which is a common location for osteosarcoma, could represent osteosarcoma. Alternatively, this could represent osteomyelitis associated with either fungal or bacterial infection. In most cases bacterial infection requires a penetrating wound, which was not documented in the history. Fungal infections may be haematogenous, and are often located in the region of the nutrient foramen or near areas of high-volume and low velocity blood flow. Fine needle aspirates may be useful for further evaluation. Biopsies may also be beneficial. If fungal aetiologies are considered likely, fungal titres may also be useful.
Sadly the bone lesion was confirmed as an osteosarcoma and the dog is undergoing chemotherapy at the moment as her owners opted against amputation.