Acute And Chronic Diarrhea


We classify diarrhea as "acute" or "chronic". Chronic diarrhea is any condition that continues for more than three weeks. Many causes of acute diarrhea are also causes of chronic diarrhea.

Diagnosis Of Bowel Disease

Plain x-rays are useful when there is vomiting associated with diarrhea, abdominal pain or we can feel an abnormality. Plain x-rays reveal gas, foreign bodies, masses or obstructions and some detail of the lining and thickness of the intestinal wall.

Microfine barium contrast x-rays are useful for seeing lesions such as ulcers in the duodenum and for watching the movement and calculating the speed of activity in the intestines.

Ultrasound detects masses and visualises enlarged lymph nodes associated with the intestines. It is useful for calculating the thickness of intestinal wall.

Endoscopy is ideal for looking in the first part of the intestines, from the stomach or the last part, from the anus. The limitation of endoscopy is that it does not reach the middle parts of the small intestines, the jejunum. Endoscopic biopsies help make very accurate diagnoses of causes of intestinal diseases.

Blood tests for cobalamin (B12) and folate give a good indication of absorption from the intestines. For example in Small Intestine Bacterial Overgrowth (SIBO) folate increases while cobalamin decreases.


Acute diarrhea is always treated symptomatically. Known causes such as diet, drugs, toxins or parasites are eliminated. Allow your pet to drink but withhold food for a few hours. Rehydration with fluid therapy is essential when acute diarrhea is caused by a parvovirus infection. Antibiotics are seldom used unless diarrhea becomes chronic and secondary bacterial infection is suspected. See us immediately if your pet is lethargic, has a fever or passes blood. When diarrhea is chronic, any of the diagnostic methods described may be used to differentiate between small intestine and large intestine involvement.

Malabsorption Syndrome

Malabsorption is caused by damage to the villi of the small intestines as a result of food-sensitivity and parasitic, bacterial or viral infection, especially canine and feline parvoviruses. It also occurs as a consequence of inflammatory bowel disease or exocrine pancreas insufficiency. Pets suffering from malabsorption look malnourished although they eat voraciously. Their stools are large, greasy and smelly. Because fat is not digested, the hair around the anus may be oily. Malabsorption syndrome in general is diagnosed by clinical examination and blood testing for B12 (cobalamin) and folate. A biopsy is often needed to determine and exact cause. Treatments are appropriate for the specific cause of malabsorption but usually involve diet management.

Inflammatory Bowel Disease (IBD) - Colitis

This is a group of diseases, defined according to the cells found in the lining of the intestines, where inflammation and malabsorption cause clinical signs. Affected pets have chronic diarrhea, pass stools more frequently, experience pain when they pass stools, lose weight, look malnourished and are often anemic. IBD is perhaps the most common cause of chronic vomiting and diarrhea in dogs. The types of cells involved suggest that IBD is an immune-mediated disease and that food allergy should always be considered part of the problem. We may suggest feeding a "hypoallergenic diet", food that does not act as an antigenic challenge to your pet's intestinal immune system. Several pet food manufacturers produce hypoallergenic diets. Rice is a preferred carbohydrate because it is highly digestible. Potato, corn and tapioca all are gluten-free. Immune-suppressing drugs such as corticosteroids are useful. Anti-inflammatories such as sulfasalazine are used when inflammation is restricted to one part of the colon. Dietary fibre increases stool consistency, improves colon motility and supports the good microflora of digestion.

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