7 Persistent right aortic arch in a dog
The puppy had been obtained from a farm about a month prior to presentation. Since then he had regurgitated frequently (several times a day), especially food but also occasionally water. The food he brought up was undigested with no bile present and the regurgitation occurred passively with no abdominal effort. Regurgitation usually occurred within minutes after eating, but recently it had occurred as long as an hour after meals. There was sometimes some retching after he regurgitated. He had no problem picking up his food and his initial swallowing appeared normal. He had been very bright, but was in poor body condition.
His initial diet was a dry puppy food, free choice. The owners had tried adding water to the food, but this did not improve the clinical signs. When they first obtained him he had a good appetite, but during the week previous to admission he had been less interested in eating. The owners had been trying to tempt him to eat with a variety of foods. His faeces had usually been normal, although since the change in diet, they occasionally were soft.
The puppy was very bright and responsive, but not well grown. He was thin, with a body condition score of 2/9. His mucus membranes were pink and capillary refill time was less than 2 seconds. On oral examination his tonsils were slightly enlarged.
Thoracic auscultation revealed normal heart and lung sounds, with a heart rate of 140 beats per minute (bpm) and a respiratory rate of 24 breaths per minute. There was no evidence of pain on abdominal palpation and the only abnormality found was increased gas in the small intestines. Rectal temperature was 38.6° C.
An oesophageal foreign body was unlikely (but not impossible) because of the duration of the clinical signs. Immune-mediated disorders (e.g. myasthenia gravis) and tumours were also unlikely in this young dog as they generally occur later in life.
Diagnostic techniques that were indicated in this puppy included plain thoracic radiographs, which help diagnose megaoesophagus and foreign body. A positive contrast study using barium mixed with dog food would also help localize and characterize oesophageal disorders such as strictures, PRAA and dysmotility. Oesophageal endoscopy would also be useful to visualize the mucosa of the oesophagus.