Pet Care: Diarrhea

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Diarrhea...A Common Problem in Dogs

Intestinal upset and diarrhea are one of the most common problems encountered in dogs. The condition can originate in either the small or large intestine and, depending on the origin, the characteristics of the stool are different:

Small intestinal diarrhea:

Characterized by large volumes of watery stool and is usually more serious than large intestinal diarrhea.

Large intestinal diarrhea:

Produces small amounts of stool with increased urgency. Large intestinal diarrhea (colitis) is more commonly seen in dogs.

What is colitis?

Colitis is caused by injury to the innermost lining of the colon (called the mucosa). The mucosa has numerous mucus glands that protect the colon from injury and lubricate the passage of feces. The main functions of the colon are to absorb water and store feces until the animal defecates. In dogs with colitis, water is not effectively adsorbed, and the ability of the colon to store feces is impaired.

Acute colitis occurs most commonly in dogs and usually responds quickly to symptomatic therapy. Chronic colitis is more challenging and may require life-long treatment.

Inflammation in the colon can decrease the movement of the colon. The colon normally moves the feces slowly back and forth, enabling maximum absorption of fluids. When this movement is abnormally slowed, the contents pass too quickly through the colon and diarrhea ensues.

Signs of colitis:

The most obvious signal of colitis is loose stool, mucus and/or blood, and an increased frequency of passage. The pet often strains to pass small amounts of stool and may actually appear to be constipated. Vomiting may occur in severe cases.

A diagnosis of colitis is generally straight-forward given the classic findings though how one should proceed depends on the course of the signs. Is the problem acute (i.e. suddenly there) or chronic (been happening for several weeks regularly) or episodic (happens then goes away then happens again)?

Cases of acute colitis are generally minor and can be cleared with a short course of medication and/or dietary therapy. If your pet has had symptoms of episodic or chronic colitis, a search for the actual cause should be sought.

Common causes of colitis:

• Parasites: Whipworms and Giardia
• Dietary indiscretion: Raiding the garbage, etc.
• Bacteria: Clostridium perfringens, Salmonella and Campylobacter.
• Food allergies
• Irritable bowel syndrome: Often seen in excitable dogs that are stressed or apprehensive.
• Inflammatory bowel disease (IBD): This complex of diseases is due to an invasion of the wall of the large bowel by certain types of body cells. Eosinophilic colitis and lymphocytic-plasmacytic colitis are two examples.
• Other - such as fungal infections, polyps, tumors, etc.

Diagnosis of colitis:

• History: It is very important to observe and describe all factors such as type and frequency of stool, diet, stress factors, straining, etc.
• Laboratory analysis: Fecal exams are a basic part of the patient analysis to determine the presence of parasites, bacteria, undigested nutrients, and blood.
  
  
  Fecal cytology of Clostridium perfringens sporesthe spores have a safety pin appearance.
• Radiography
• Colonoscopy and biopsy: Direct visual exam and biopsies often provide the conclusive diagnosis in many cases of chronic colitis.

Medications

• Metronidazole (Flagyl): Has anti-inflammatory properties in the large intestine as well as ability to kill harmful organisms such as Clostridia and Giardia.
• Bismuth subsalicylate (Pepto-Bismol): Decreases intestinal secretions, protectant and modest antibacterial effects. More palatable if refrigerated.
• Motility modifiers (Lomotil and Imodium): Increase fluid and water resorption.
• Other medications: Include antibiotics, cortisone and dewormers.

Dietary management:

Most pets with a sudden onset of diarrhea will benefit from fasting ("bowel rest") for 12 to 24 hours. This is followed by a bland diet fed frequently and in small quantities for 3 to 7 days. A home-made bland diet consists of one part cottage cheese, lean meat or skinned and cooked chicken with two parts boiled white rice. Many pet owners prefer the convenience of Hill's Prescription Diet I/D.

Many cases of chronic colitis respond to one of two dietary approaches:

• Increasing the amount of fiber in the diet. Fiber normalizes intestinal transit time, increasing water absorption from the colon. Therefore, there is less water lost in the stool.
• Feeding a diet that is not likely to stimulate an allergic reaction (hypo-allergenic diet).

Most cases of acute colitis are generally minor and can be cleared with a short course of medication and dietary therapy. If your pet is not showing good response within a few days, please notify us.