ABSTRACTPrimary lymphoedema is a swelling of a part or parts of the body due to a congenital defect in the lymphatic system. This report describes our experience with a case in a Rough Collie.

During early fetal life six pair of aortic arches surround the esophagus and trachea. Normal maturation and selective regression of these structures form the adult vasculature. Abnormal location or development of the aortic arches may result in pressure on adjacent organs. Vascular ring anomalies must be considered with any patient with a history of regurgitating food shortly after eating. Physical examination, test feedings, survey and contrast radiographs may give an accurate impression of the problem but a final diagnosis can only be made following surgical exploration. In the case presented, the dog had all the clinical and diagnostic signs suggestive of a vascular ring anomaly. Thoracotomy and elimination of the vascular constriction around the esophagus was both diagnostic and therapeutic for the condition. It is important that owners be made aware that surgical correction of the stenosis does not guarantee a successful conclusion to the case. If the dilation of the esophagus cranial to the stenosis is severe, accumulation of food with subsequent regurgitation may persist. A dilation of the esophagus caudal to the stenosis is present in a large percentage of cases and this also may result in an unrelenting problem. Unfortunately, the probability of these complications cannot be accurately evaluated prior to treatment.The hereditary potential for this defect must also be considered. Congenital vascular anomalies such as patent ductus arteriosus would seem to have a hereditary basis. Therefore, it is probably correct to advise against breeding affected animals. Further, the inbreeding of nonaffected animals which come from litters containing affected animals should be avoided.

Clinical Findings and Treatments During examination the dog remained in sternal recumbency, being unable to stand. The rectal temperature was 95°F. The extremities were cold. The heart rate was 126 per minute and the femoral pulse was weak. Mucous membranes were pale and the capillary filling time slow. Respirations were 40 per minute and shallow. The abdomen was tense and tympanic on percussion. Treatment for shock was begun immediately by administering intravenously 500 mg tetracycline hydrochloride', 70 mg prednisolone sodium succinate2 and 2000 ml of a balanced electrolyte solution with 5% dextrose.3 The fluid was administered continuously over the treatment period. Radiographically, loops of bowel grossly distended with gas, were evident throughout the abdomen (Figure 1). It was decided that exploratory laparotomy was necessary to determine the cause of the condition. Anaesthesia was induced with 4% halothane 4 given by face mask. The dog was in-