Primary oesophageal squamous cell carcinoma in a cat with bradycardia and ionised hypercalcaemia

An adult male domestic shorthair cat was presented for vomiting and anorexia, with a three-month history of weight loss. Bradycardia was documented during physical examination and was diagnosed as sinusal by electrocardiography. Blood electrolytes analysis revealed a marked ionised hypercalcaemia. Thoracic radiographs revealed a large soft tissue opacity at the level of the distal oesophagus. Subsequent thoracic ultrasonography and oesophagoscopy confirmed the presence of a tissue mass infiltrating distal oesophagus, oesophagogastric junction and neighbouring tissues. After biopsy and histopathological analysis, a squamous cell carcinoma (SCC) was diagnosed. Sinus bradycardia was assumed to be related to an increased vagal tone due to the close proximity of the vagal nerve with the infiltrative lesion or, less likely, severe hypercalcaemia. This case describes an atypical clinical presentation of an SCC in an uncommon location. Furthermore, to the authors' knowledge, this is the first report of hypercalcaemia associated with oesophageal SCC in a cat.