Thoracic radiographic findings of canine spirocercosis in Australia

Canine spirocercosis in Australia has been poorly described in the veterinary literature. The objectives of this multicentre retrospective case series were to increase the awareness of veterinarians (including teleradiology providers) regarding Spirocerca lupi in Australia and to describe the thoracic radiographic findings of dogs infected with S. lupi with comparison to other endemic regions. Fifty-nine dogs with a diagnosis of canine spirocercosis were recruited from veterinary practices located in subtropical and tropical Australia. Many (54/59; 92%) originated from Mount Isa, Queensland, due to proactive screening. Thoracic radiographs identified 42 oesophageal masses in 35/59 (59%) of affected dogs. Identification of oesophageal masses was nearly always facilitated by oesophageal gaseous distension after gastro-oesophageal endoscopy, sedation or anaesthesia (33/35, 94%). Oesophageal masses were most frequently centred at T8. Where the aorta was visualised, aortic enlargement was detected in 17/42 (40%) dogs. Spondylitis was frequently detected (32/59; 54%) and most frequently located at T8-11. Spondylosis deformans was less frequently detected (14/59; 24%) but in 7/14 (50%) studies it was present concurrently with spondylitis. Spondylitis had varied morphological features, some of which were contrary to previously reported definitions. Despite this, the radiographic appearance of spondylitis allowed relatively reliable differentiation from spondylosis deformans and added significant confidence to the radiographic diagnosis of spirocercosis. Pleural effusion (5/59; 8%) was the most frequent additional radiographic finding. In conclusion, thoracic radiographic findings of canine spirocercosis in Australia are similar to other endemic regions and S. lupi is present in multiple regions of Australia not previously reported.