5-Month-Old Male Mixed Breed

By Kylie Gambler, c/o 2022

Signalment & History

5-month-old male mixed breed dog who presented with a history of vascular ring anomaly and regurgitation.

Findings

• The caudal portion of the cervical esophagus and intrathoracic esophagus cranial to the T5, are markedly distended by heterogeneous soft issue opaque material, more severe at the intrathoracic portion where the ventral wall of the esophagus extends to the ventral thoracic wall, forming a well-defined and smoothly margined saccular structure. This structure causes moderate ventral and right-ward displacement of the trachea, caudal and left-ward displacement of the left cranial lung lobe, and moderate caudal and right-ward displacement of the cardiac silhouette.
• There is a mild rightward shift of the cardiac silhouette. The cardiovascular structures are otherwise normal.
• On the right lateral projection, in the ventral aspect of the caudal subsegment of the left caudal lung lobe, there is a mild increase in pulmonary opacity causing a decrease in the visualization of the pulmonary vessels, representing an unstructured interstitial pulmonary pattern.
• On the lateral projections, approximately at the 4th intercostal space, superimposed with the ventral aspect of the lungs, there are a few well-defined gas opacities.
• Several pleural fissure lines are identified between the left cranial and caudal lung lobes.
• An endotracheal tube is seen in the caudal cervical trachea.
• There are multiple open physes visible, consistent with the young age of the patient.

Diagnosis

• Segmental megaesophagus with undigested food and/or foreign material. The primary differential is vascular anomaly such as persistent right aortic arch. The described gas opacities may represent gas within a caudoventral extension or fold of the esophagus, or less likely gas within the pleural space.
• Ventrally distributed unstructured interstitial pulmonary pattern in the left cranial lung lobe, representing aspiration pneumonia or atelectasis.
• Bilateral pleural fissure lines, most consistent with scant pleural effusion.

Conclusions

The patient underwent thoracoscopy for correction of a vascular ring anomaly (persistent right aortic arch with left ligamentum arteriosum and aberrant left subclavian artery).

Etiology of Vascular Ring Anomaly

Vascular Ring Anomaly is a congenital defect of the great vessels which causes a displacement or constriction of the esophagus. During development, there are six pairs of aortic arches which typically form and regress, eventually resulting in a single aortic arch, a left and right carotid artery, the right subclavian artery, and the pulmonary artery with a ligamentous attachment. The right fourth arch will typically regress completely and prevent entrapment of the esophagus. Vascular ring anomaly could occur due to abnormal development of either the third, fourth, or sixth arches. However, most commonly occurs when the right fourth arch does not regress, causing the esophagus to be constricted.¹

Diagnosis

The time it takes to diagnose vascular ring anomaly depends on the degree of esophageal displacement. Oftentimes animals are 2-6 months old by the time they start showing clinical signs. Clinical signs include high appetite without weight gain, regurgitation, and possibly fever, cough, or respiratory distress with crackles on auscultation. Radiography, angiography, CT, and MRI may be used to aid in diagnosis.¹

Treatment

The best treatment for patients with vascular ring anomaly is surgery to correct the vessel constricting the esophagus. Medical management is not recommended; however, the patient can be supported by feeding a gruel diet in an elevated dish, or a feeding tube if necessary.¹

Prognosis

The prognosis is good to excellent for patients treated quickly after diagnosis, and is poorer the longer treatment is delayed.¹

References:

1. Rishniw, Mark. “Vascular Ring Anomalies.” Edited by Kari Rothrock, VIN, 28 May 2015, www.vin.com/Members/Associate/Associate.plx?DiseaseId=17.