Robert G. Sherding, DVM, DACVIM

Molecular studies have determined that the intestines of dogs and cats harbor a complex population of commensal bacteria, referred to as the microbiota. Depending on its composition, the microbiota can be beneficial or harmful to the host.

Giardia duodenalis (also known as G. intestinalis, G. lamblia) is a pear-shaped, binucleated, flagellated protozoan parasite that infects the small intestine, impairs mucosal absorption, and causes diarrhea.

Chronic hepatitis associated with abnormal accumulation of copper in liver cells is emerging as an important form of chronic liver disease in dogs.

Esophagitis is characterized by acute or chronic inflammation of the esophagus resulting from mechanical, corrosive, or acid-peptic injury to the mucosa. Mild esophagitis may be self-limiting or resolve with medical treatment.

Clinical signs suggestive of esophageal disease include regurgitation, dysphagia, odynophagia, salivation, retching, gagging, and repeated swallowing. Other less specific signs can include weight loss, anorexia or ravenous appetite, and depression.

Idiopathic inflammatory bowel disease (IBD) is characterized by chronic gastrointestinal signs associated with diffuse accumulation of lymphocytes and plasma cells in the lamina propria and morphologic abnormalities of the intestinal mucosa and epithelium.