The histological appearance of peroral small intestinal biopsies in clinically healthy dogs and dogs with chronic diarrhea.

A survey of the histology of 2,024 small intestinal suction and forceps biopsies in 400 dogs, consisting of 17 clinically healthy control dogs and 383 dogs with chronic diarrhea is presented. Three and a half percent of the suction biopsies and 22.6 percent of the forceps biopsies were unsuitable for examination, making a diagnosis impossible in 9 dogs, and in 0.4 percent antral mucosa was present. Biopsies could be obtained from the proximal one third of the small intestine. The normal histology, including mean villous length, its standard deviation and its range is described in the 17 control dogs. A classification of enteritis in dogs is given. Villous atrophy without enteritis was found in 55 dogs with chronic diarrhea; 51 dogs had moderate and four severe villous atrophy. Villous atrophy combined with enteritis was found in 93 dogs, 57 of which had lymphocytic-plasmacytic enteritis, 14 had eosinophilic enteritis, six catarrhal, four ulcerative, 11 a combination of lymphocytic-plasmacytic and eosinophilic enteritis and one dog had a combination of lymphocytic-plasmacytic and catarrhal enteritis. Enteritis without villous atrophy was found in 50 dogs: 39 had lymphocytic-plasmacytic enteritis, four eosinophilic, two catarrhal, one purulent (microabscesses), three a combination of lymphocytic-plasmacytic and eosinophilic enteritis and one dog had focal necrosis. Twelve dogs showed a lymphosarcoma and in eight other dogs a differential diagnosis of lymphosarcoma and/or enteritis was made. One carcinoma was found. Other findings were hemorrhages, oedema, erosions, muscular hypertrophy in the villi, an increased or decreased number of intraepithelial lymphocytes, an increased or decreased number of goblet cells, lymphangiectasia, crypt cysts, crypt abscesses and gastric metaplasia. Some breeds, such as the German Shepherd dog, Bouvier des Flandres, Spaniel, Collie, Great Dane and Retriever appear to be more susceptible than other breeds for villous atrophy and enteritis. A slight prevalence of the German Shepherd dog, Doberman Pinscher and Rottweiler was also observed for eosinophilic enteritis. Mild villous atrophy is mostly found in dogs aged 0-4 years, whereas severe villous atrophy is found in dogs older than 4 years. Further breed, age or sex predisposition could not be found. The method appears especially useful for diffuse mucosal lesions of the proximal small intestine.