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Milo case study: A puppy with regurgitation and ill-thrift

30th March 2021

A 14-week-old male entire JRT/Westie crossbreed was referred to Highcroft Veterinary Referrals Internal medicine and Soft tissue surgery services due to a history of chronic regurgitation of food and wheezing that was first noted upon weaning onto solid food. The patient had been in the owner’s possession for 8 weeks and failure to thrive/gain weight and chronic regurgitation were reported. Mild improvement had been seen with altered feeding regime and general husbandry. No other issues were reported and the patient remained bright and alert.

On clinical examination by Internal Medicine Clinician Jen Stallwood, Milo was very bright, alert and responsive. He was in a lean body condition (BCS 3/9) weighing 1.78 kg, adequately hydrated and cardiovascularly stable. Thoracic auscultation was unremarkable; no lung or heart abnormalities were identified. Abdominal palpation was unremarkable. Peripheral lymph node palpation documented a moderately enlarged left submandibular lymph node. A rectal temperature was normal (38.5ºC). Palpation of the neck identified a soft palpable structure with fluid filled contents suspected to be oesophageal in origin. The remainder of the clinical examination was unremarkable.

Differential diagnoses:

  • Congenital megaoesophagus/dysmotility; secondary to vascular ring anomaly
  • Oesophagitis secondary to previous vomiting as a puppy (short-lived episode; self-limiting)
  • Hiatal hernia

Diagnostic imaging was recommended via fluoroscopy and or computed tomography to try to confirm an oesophageal problem, with routine bloods + infectious/endocrine screening for causes of oesophageal dysmotility. Oesophagoscopy +/- electromyography and/or biopsies as indicated were also discussed. First Jen reviewed the referring vets’ thoracic radiographs. Bilateral thoracic radiography demonstrated dilation of the cranial oesophagus containing what appeared to be ingesta as well as evidence of aspiration pneumonia (Figure 1). This increased the index of suspicion of a vascular ring anomaly being the underlying cause of Milo’s clinical signs.

Enlarged Oesophagus

Figure 1- Shows an enlarged oesophagus and evidence of aspiration pneumonia in the lung fields.

Based on the above findings and financial constraints Jen recommended surgery with our soft tissue surgery service. Surgery resident Anna Condon discussed the procedure and interim home management with Milo’s owners. Several weeks later, Milo was admitted for surgery. He was carefully assessed by Specialist anaesthetist Jo Murrell and anaesthesia nurse Ffion who prepared him for general anaesthesia and surgery. Under anaesthesia, CT imaging confirmed the presence of a vascular ring anomaly. The images were reviewed by Specialist Imaging Clinicians Harriet Hahn and Lizzie Reeve who identified a segmental megaoesophagus extending throughout the cervical and cranial thoracic region with termination of dilation at the level of the heart base. A double aortic arch with the right aorta being dominant (left aorta 2.7mm diameter, right aorta 4.9mm diameter) was present.  There was no current evidence of aspiration pneumonia. The final diagnosis was a double aortic arch vascular ring anomaly with oesophageal and tracheal compression; aberrant subclavian anatomy with the left and right respectively branching from their aortic arch (Figure 2).

Reconstruction of Milo's CT

Figure 2- 3D reconstruction of Milo’s CT showing the abnormality.

Originally a tentative working diagnosis of persistent right aortic arch had been discussed with the owner and referring vet. CT imaging showed this was not the case, and Milo’s vascular ring anomaly was actually a double aortic arch, a much rarer anomaly accounting for approximately 1% of all vascular ring anomalies! This put Milo into a very small number of patients worldwide diagnosed with this congenital anomaly.

Milo was taken to surgery following updating the owner and discussion of the unusual pathology. Mechanical ventilation was provided throughout the procedure. Surgery was performed by Specialist surgeon Ivan Doran with the help of the surgery resident Anna and intern Vicky Roberts.  A left 4th intercostal lateral thoracotomy was performed. Upon completion of thoracic exploration, blunt dissection into the mediastinum was performed. No gross abnormalities were identified in the mediastinum other than the cranial megaoesophagus and a 2.7mm left aortic arch. Blunt dissection to isolate the aberrant vessel was performed. Temporary occlusion via vascular clamps for 10 minutes showed no change in heart rate or blood pressure (Figure 3).

Isolated left aortic arch

Figure 3- The isolated left aortic arch temporarily occluded intra-operatively prior to transection and closure.

The vascular clamps were adjusted to have a pair either side of the chosen transection point. The vessel was then transected and each end was oversewn with non-absorbable suture material. Further dissection deep to the arch to the level of the oesophagus was performed to ensure no obvious fibrous bands were causing further constriction. Orogastric intubation was performed and confirmed an appropriate diameter of the oesophagus. Routine thoracostomy tube placement was performed and the chest wall was closed routinely. Air was evacuated from the pleural cavity via the thoracostomy tube, restoring sub-atmospheric pressure. The patient received an intercostal nerve block intraoperatively and was maintained on a continuous rate infusion (CRI) of fentanyl initially. Recovery from general anaesthesia was uneventful. From anaesthetic recovery to discharge, Milo’s clinical condition progressively improved. The thoracostomy tube air and fluid production decreased progressively during hospitalization and the tube was removed 18 hours postoperatively. Milo’s first meal was offered 16 hours postoperatively as meatballs of Royal canin GI diet, fed with the patient’s head raised. Milo was discharged one day postoperatively with instruction for strict exercise restriction for 3 weeks, a protective bodysuit, and oral. The owners were instructed to continue to small frequent meals until re-evaluation. A recheck was performed 2 weeks postoperatively. The owner reported near complete resolution of Milo’s clinical signs starting one day after surgery. He was acting like a normal puppy, with great energy and no evidence of wheezing. After discharge postoperatively he was being fed 10g AVA daily for 2 weeks. He was reported to have 2 episodes of regurgitation while on this feeding regimen. At the time of recheck, on physical examination he was eupneic and no wheezing was auscultated. No imaging was performed based on financial constraints. To date, Milo has continued to do well with thrice daily feeding from a bowl on the floor (Figure 4) and the entire HVR team are very pleased to hear of his progress!

Milo 2 weeks after surgery

Figure 4- Milo at his 2 week post-operative check.

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