Severe Pleural Effusion in a Dog Affected by Larval Mesocestodiasis

A 4-year-old, 20 kg, female mixed breed dog was referred to our Veterinary Teaching Hospital for severe respiratory distress. Thoracic ultrasonography revealed severe pleural effusion with multiple anechoic cystic structures within the fluid. Abdominal cavity presented few small and irregular cystic structures. Diagnosis of infection by larval stages of Mesocestoides spp. on the basis of a PCR approach was performed and therapy with oral fenbendazole was started. Due to an incomplete clinical response, the dog underwent to remove metacestodes cysts by surgical debridement. The dog showed no recurrence of clinical signs for 12 months after the surgery. Pleural larval cestodiasis should be added as a differential diagnosis in the list of diseases causing pleural effusion in dogs.