A Case of FEP

An 8-month-old entire Labrador was presented at SCVS with history of recent ascites. The patient had 3 months earlier abdominal surgery at the referring practice to remove a linear foreign body in stomach and duodenum. The dog recovered well from the previous surgery.

The owners did not report any problem at home, just abdominal distension. The dog was bright and alert. The physical examination revealed moderate abdominal effusion. The vital parameters were within normal range. Haematology was unremarkable, as well as biochemistry and ammonia. Bile acids pre- and post-prandial, extended clotting profile including D-dimer and urine analysis were within normal limits. Urine culture was negative.

An abdominal ultrasound revealed moderate abdominal effusion and packed small intestine, without signs of ileus. No other abnormalities were detected. Analysis of the fluid was consistent with modified transudate with negative culture.

Abdominal CT revealed peritoneal effusion with thickened omentum encapsulating the GI tract in the mid-abdomen (see picture 1). Thoracic CT was unremarkable. At this stage a provisional diagnosis of fibrosing encapsulating peritonitis was made based on the CT finding and lack of any other clinico-pathological findings. At surgery all the abdominal organs looked encapsulated by a thick omentum (see picture 2). No other gross abnormalities were found. Multiple biopsies of the omentum were taken. Histology showed marked, diffuse granulation tissue with lympho-plasmacytic inflammation. Cultures of the tissue were negative. The pathologic finding confirmed the diagnosis of fibrosing encapsulating peritonitis (FEP).

FEP is a clinical entity characterized by a partial or complete encasement of the abdominal organs by thick layers of collagenous connective tissue. FEP in human medicine can be classified as primary (idiopathic) or secondary. The secondary FEP can be caused by several causes such as: peritoneal dialysis, abdominal surgery, abdominal trauma, liver disease (e.g. cirrhosis, neoplasia), drugs, etc.

In veterinary medicine some cases have been reported most of them are secondary to infectious disease (bacteria, leishmania), primary liver disease and asbestos exposure, although few cases seem idiopathic.

As the exact cause of FEP is unknown the treatment is direct mainly to treat the inflammation and modulate fibroplasia.

Andrea Di Bella DVM, DipECVIM-CA, CertSAM, MRCVS. RCVS and European Specialist in Small Animal Medicine