Diagnostic imaging (C)

2.3.4.1 Abdominal ultrasonography (see 1.3)

Abdominal ultrasonography is used for evaluating the thick­ness of the gastrointestinal wall and for guiding the clinician in examining and aspirating abdominal masses and infiltrated or­gans.

2.3.4.2 Endoscopy (see 1.5)

Gastrointestinal endoscopy allows visualization and sampling of the mucosa from stomach, duodenum, terminal ileum, co­lon, and rectum. Endoscopy can be used to identify lesions such as ulcers, erosions, inflammation, and lymphangiectasis.

2.3.4.3 Abdominal radiography (see 1.3)

Survey abdominal radiographs and contrast radiography are rarely useful for the diagnosis of an underlying cause in pa­tients with chronic diarrhea. Radiography is, however, helpful in revealing masses and foreign bodies, if present.

Inflammatory bowel disease (C1a; see 9.2)

Intestinal biopsies are required for definitive diagnosis of this disorder. The term inflammatory bowel disease (IBD) refers to a diverse group of chronic enteropathies characterized by idi­opathic infiltration of the gastrointestinal mucosa and some­times the submucosa with inflammatory cells. Infiltrations of either single-cell or mixed-cell populations may be seen. Of­ten, one or two cell types predominate (e. g., in eosinophilic or lymphoplasmacytic enteritis and /or colitis).

Intestinal lymphangiectasia (C1b; see 5.3.9)

Intestinal lymphangiectasia is an obstructive disorder of the intestinal lymphatic system. There are many potential causes of lymphatic obstruction, but in most cases lymphangiectasia is idiopathic. Yorkshire Terriers, Norwegian Lundehunds, and Soft-coated Wheaten Terriers appear to be predisposed. Hy- poalbuminemia, hypocholesterolemia, and lymphopenia are common findings. Results obtained upon histological exami­nation of intestinal biopsies often show typical changes. In some circumstances, full-thickness biopsies are needed.

Gastrointestinal neoplasia (C1c)

Lymphosarcoma and adenocarcinoma are the most common intestinal tumors in dogs. Clinical signs usually include weight loss, anorexia, diarrhea, melena, vomiting, and abdominal dis­comfort. Ultrasound is most useful for evaluating intestinal thickness and aids in revealing non-palpable masses.

Key Facts

■ The etiology of chronic diarrhea in dogs and cats often remains unclear.

■ In order to monitor the progress in a patient with chronic diarrhea, it is important that the pet owner daily evaluates the consistency of the feces using a fecal scoring system.

■ Diet-related diarrhea should be excluded before treatment trials with drugs are initiated.

■ Tylosin can be effective in resolving chronic diarrhea in dogs.

References

1. Westermarck E, Wiberg M. Exocrine pancreatic insufficiency in dogs. Vet Clin SmallAnim 2003; 33: 1165—1179.

2. Westermarck E, Skrzypczak T, Harmoinen J et al. Tylosin-responsive chronic diarrhea in dogs. J Vet Intern Med 2005; 19: 177-186.

3. Westermarck E, Frias R, Skrzypczak T. Effect of diet and tylosin on chronic diarrhea in Beagles.J Vet Intern Med 2005; 19: 822-827.

2.4