CASE REPORT Congenital oesophageal stricture in a Japanese shiba inu An 11-week-old, female, Japanese shiba inu, weighing 1  3 kg, was presented with a history of intermittent regurgitation since birth. An oesophagram showed a partial obstruction of the caudal cervical oesophagus associated with a narrow, transverse tissue band. Following surgical resection, the regurgitation resolved and the dog attained a normal bodyweight. Histological examination revealed focally hyperplastic epithelium with dense fibrous underlying connective tissue forming the band. The diagnosis was a congenital oesophageal stricture. E. FOX, K. LEE, C. R. LAMB, J. REST, S. J. BAINES AND D. BROCKMAN Journal of Small Animal Practice (2007) 48, 709–712 DOI: 10.1111/j.1748-5827.2007.00361.x INTRODUCTION Congenital oesophageal stricture is defined as intrinsic stenosis of the oeso- phagus caused by congenital malforma- tions of the oesophageal wall architecture (Amae and others 2003). The oesophagus is formed from the portion of foregut between the caudal limit of the pharynx and the fusiform enlargement of the stom- ach. Initially very short, this portion elon- gates as the heart descends from the neck into the thorax. The oesophagus is also involved in the origin of the lower respi- ratory tract because the foregut endoderm supplies the lining epithelium of the respi- ratory organs as they form from the meso- derm. At one stage, the rapid proliferation of the endodermal lining completely obstructs the lumen, but the passage is later restored (Dyce and others 1996). Congenital oesophageal stricture in humans is rare: the incidence is estimated at 1:25,000 to 1:50,000 live births (Bluestone and others 1969), and approx- imately 500 cases have been reported to date. Associated congenital anomalies reported in one-third of these cases include oesophageal atresia, intestinal atresia, cardiac defects and chromosomal anomalies (Fekete and others 1987). In humans, three types of congenital oesophageal stricture are described (Fekete and others 1987): fibromuscular thicken- ing, which is associated with reduced myenteric nitrinergic neurons (Singaram and others 1995); cartilaginous ring, which results from sequestration of tracheobronchial precursor cells in the oesophageal wall caused by defective em- bryologic separation of the primitive fore- gut from the respiratory tract (Anderson and others 1973, Rose and others 1975); and membranous web, which results from a disturbance of recanalisation (Amae and others 2003). These lesions usually arise alone, but in rare cases, they can arise simultaneously (Takamizawa and others 2002, Nagae and others 2005). Congenital oesophageal stricture is a rare abnormality in animals. There are reports of two affected foals (Stewart and Reinert- son 1983, Clabough and others 1991) and two affected dogs (Schnelle 1931, Pande and others 1995). Neither of the latter reports ascertained the underlying patho- logical changes. CASE HISTORY An 11-week-old, female Japanese shiba inu with a history of intermittent regurgi- tation of both solids and liquids since birth was presented to the Queen Mother Hos- pital for Animals. The dog had been weaned on semisolid food (Hill’s a/d) at seven weeks of age and was fed from an elevated position. Physical examination revealed a bright, small puppy in poor body condition, weighing 13 kg, but was otherwise unremarkable. Haemato- logically there was reduced mean red blood cell volume (594 fl: reference range 60 to 77 fl) and reduced mean red blood cell haemoglobin concentration (177 pg: reference range 195 to 245pg) compa- tible with nutritional iron deficiency. An oesophagram using barium sulphate suspension (Baritop 100; Sano Chemia Diagnostics UK Ltd) mixed with Hill’s a/d diet demonstrated a persistent, focal, curvilinear filling defect within the caudal cervical oesophagus and dilatation of the oesophagus compatible with partial ob- struction (Fig 1). Some food passed this lesion and entered the stomach. The cau- dal oesophagus had a normal appearance and motility. Queen Mother Hospital for Animals, The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Herts AL9 7TA Journal of Small Animal Practice  Vol 48  December 2007  Ó 2007 British Small Animal Veterinary Association 709