Abstract
Background:
Gastroesophageal intussusception is a rare condition in dogs, most commonly presenting as an acute, life-threatening disease. Intermittent intussusception is suspected to be the cause of clinical signs in dogs suffering chronic clinical signs, but the relationship between supposedly intermittent intussusception and other oesophageal diseases is poorly understood. Intermittent disease has only been reported in one endoscopic study where concurrent assessment of the hiatus was not possible, and spontaneous reduction has never been definitively demonstrated tomographically.

Case Description:
An 11-year-old neutered male Australian Terrier, previously diagnosed with a hiatal hernia, was referred for evaluation of a sublumbar mass identified on abdominal ultrasound. Computed tomography revealed a mass arising from the right iliopsoas muscle, and haemangiosarcoma was diagnosed cytologically. On pre-contrast and delayed post-contrast images, the stomach was in its normal position. However, on venous-phase images acquired between these time points, the gastric fundus was cranially herniated through the oesophageal hiatus into the caudal oesophageal lumen, with the gastroesophageal junction remaining appropriately positioned. These findings were consistent with intermittent, self-resolving gastroesophageal intussusception. No treatment was pursued for the intussusception, and treatment for the haemangiosarcoma was declined. A poor prognosis was given, and the patient died five days later without post-mortem examination

Conclusion:
This represents the first reported case of gastroesophageal intussusception in a dog tomographically determined to be self-resolving, and the first documented in association with an untreated hiatal hernia.

Key words: Chronic; Gastroesophageal; Intermittent; Intussusception; Transient.