Acquired uretero‐jejunal fistula following surgical excision of a subcutaneous, metastatic mast cell tumour in a dog

An 8‐year‐old, female, neutered labrador retriever presented for surgical excision of a subcutaneous mast cell tumour and extirpation of the right inguinal and right medial iliac lymph nodes. Histology confirmed a completely excised, low mitotic count subcutaneous mast cell tumour with lymph node metastasis. Vinblastine and prednisolone were administered as adjunctive chemotherapy. Six weeks post‐operatively, the dog presented dehydrated, tachycardic and pyrexic, with haematochezia, vomiting and abdominal pain. Coeliotomy revealed a communication between the jejunum and the proximal right ureter, with no obvious aetiology identified. Right ureteronephrectomy was performed, with debridement and closure of the affected jejunum. Histopathology reported a subacute to chronic neutrophilic and necrohaemorrhagic pyelonephritis and haemolytic Escherichia coli, resistant to amoxicillin clavulanate, was cultured. The dog recovered and re‐started the chemotherapy protocol following restaging 2 months post‐operatively. Unfortunately, 7 weeks after starting this protocol, the patient developed acute necrotising pancreatitis following dietary indiscretion and was electively euthanased.