Suspected paraneoplastic syndrome of inappropriate antidiuretic hormone secretion associated with a gastric adenocarcinoma in a dog

This report describes a suspected case of paraneoplastic syndrome of inappropriate antidiuretic hormone (SIADH) in a 5‐year‐old male entire Australian Kelpie associated with a gastric adenocarcinoma. The dog had a history of chronic vomiting and presented with hyponatraemia, hypokalaemia, hypochloraemia and increased urinary sodium. Computed tomography identified the presence of a gastric tumour and histopathology confirmed a pyloric gastric adenocarcinoma. Removal of the tumour via a Billroth I procedure resulted in rapid resolution of electrolyte derangements. The dog was still alive six months postoperatively with no recurrence of either SIADH or tumour at the time of publication.