Chronic Diarrhea in Dogs

Dogs

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Diarrhea is defined as the rapid movement of fecal matter through the intestine resulting in poor absorption of water, nutrients and electrolytes. With diarrhea the stools (bowel movements) become loose or runny. Chronic diarrhea refers to diarrhea that persists for three or more weeks. Occasionally the fecal material may contain fresh blood or mucus.

Chronic diarrhea is an important sign of intestinal disease in the dog. Persistent diarrhea can lead to weight loss from poor digestion and loss of important nutrients. Chronic diarrhea can lead to loss of body condition, development of a poor hair coat, and may also affect appetite and activity levels.

General Causes

Most causes of chronic diarrhea induce local irritation or structural abnormalities of the intestinal mucosa (lining). There are numerous diseases and disorders that can lead to chronic diarrhea. These include:

  • Infectious agents such as bacterial infections, protozoal agents, fungal infections, and intestinal parasites
  • Certain drugs and toxins
  • Inflammatory bowel disease, e.g. enteritis (inflammation of the small bowel) and colitis (inflammation of the large bowel)
  • Dietary intolerance or food allergy
  • Gastrointestinal cancer
  • Partial obstruction (blockage) of the intestinal tract
  • Other systemic illnesses, such as liver disease, pancreatic diseases, kidney disease, etc.
  • Small intestinal bacterial overgrowth (SIBO)
  • Lymphangiectasia, and other disorders of malabsorption (inability to absorb food stuffs or cause proteins and other materials to be lost in the feces)
  • Disorders of maldigestion (inability to digest food stuffs in the intestine)
  • Short bowel syndrome
  • Irritable bowel syndrome (spastic colon)

    What to Watch For

  • Passage of loose, watery stools that persist for more than three weeks
  • A change in color of the stool
  • Blood in the stool
  • Mucus in the stool
  • Straining to defecate
  • Increased number of stools
  • Decreased appetite
  • Weight loss
  • Poor hair coat
  • Lethargy

    • Parasititic infections such as this microscopic protozoa, Giardia, can lead to diarrhea - both acute and chronic.

    • Diseases of the pancreas can also cause diarrhea. In this case the pancreas has never properly developed and has not produced sufficient digestive enzymes. The arrows point to the very small amount of normal pancreas that developed.

    • A biopsy sample of tissue can be obtained through the endoscope.

    • An endoscope - a flexible tube - can be used to examine the stomach, intestines and colon. The patient is anesthetized for this procedure.

    Diagnosis

    Veterinary care includes diagnostic tests to help determine the underlying cause of the diarrhea and to guide subsequent treatment recommendations. Some of the following tests may be necessary to diagnose the cause of chronic diarrhea:

  • A complete medical history and physical examination

  • Multiple fecal studies (flotation, smear and cytology, zinc sulfate test) to search for intestinal parasites, protozoal parasites, and bacteria

  • A complete blood count (CBC)

  • A biochemical profile

  • A urinalysis to help evaluate the kidneys and level of hydration

  • Abdominal radiographs (X-rays)

  • Thoracic (chest) radiographs, particularly in geriatric patients and animals who are suspected to have cancer

  • Bacterial fecal cultures

  • Tests for absorption and digestion problems, such as serum trypsin-like immunoreactivity (TLI), serum folate and cobalamin levels

  • Serologic tests for certain fungal diseases

    Depending upon the clinical signs and the results of the above tests, your veterinarian may recommend further testing. These tests are chosen on a case-by-case basis:

  • Abdominal ultrasonography

  • An upper gastrointestinal (GI) barium series to help diagnose foreign bodies, partial obstructions, masses, thickening or displacement of bowel, etc.

  • Barium enema if colonic disease is suspected

  • Endoscopic examination and biopsy of the stomach, small intestine, and/or colon

  • Serum bile acids for suspected liver disease

  • A blood lead level test

  • Exploratory abdominal surgery (laparotomy) if other diagnostic tests are inconclusive, or if a disease is suspected that requires corrective surgery

    Treatment

    Symptomatic or empirical treatment may be tried in some cases of chronic diarrhea, especially if initial diagnostic tests are inconclusive and the animal is feeling well and relatively stable. Empiric treatment does not replace the need to define the exact cause of the chronic diarrhea, it at all possible. Empirical treatment may include one or more of the following:

  • Deworming for whipworms, which may not show up on routine fecal tests

  • Short course of antibiotics for clostridial bacteria

  • Changing the diet to a high-fiber diet if large bowel diarrhea is present or to a hypoallergenic diet if small bowel diarrhea is present

    Supportive therapy for ill, malnourished and unstable patients may involve hospitalization with intravenous fluids, supplemental nutrition and vitamins, intestinal protectants and adsorbents, etc.

    Specific therapy of most cases of chronic diarrhea depends upon reaching a definitive diagnosis as to the cause, and then instituting therapy for that cause. Such therapy varies widely and can involve medications, dietary changes and surgery.

    Home Care

    It is important to monitor your pet closely if he/she has chronic diarrhea. Pay particular attention to stool volume and character, the frequency of defecation, and any straining to defecate. Note the presence of any blood or mucus in the stool. Also monitor the dog's body weight, appetite and activity level. Administer all prescribed medications exactly as ordered by your veterinarian. Notify your veterinarian if you have any problems medicating your pet.

  • Chronic diarrhea in a pet can be frustrating to care for and to resolve. When chronic diarrhea is associated with vomiting, lack of water intake, fever, depression, or other symptoms, it often indicates that your pet has a potentially serious underlying disease. Such signs should prompt an immediate visit to your veterinarian.

    Causes

    There are numerous diseases and disorders that can lead to chronic diarrhea., and they include:

  • Infectious diseases can cause chronic diarrhea in any age and breed of dog, and include a variety of agents, such as the following:

    Intestinal parasites, such as whipworms, roundworms, hookworms, and tapeworms

    Bacteria, including Salmonella, Clostridium, Campylobacter, Yersinia

    Fungal agents, such as histoplasmosis, aspergillosis, phycomycosis, candidiasis

    Protozoal parasites, such as giardiasis and coccidiosis

    Infection with blue-green algae, namely protothecosis

  • Inflammatory bowel disease is a microscopic infiltration of the intestinal wall with inflammatory cells. The cause is unknown, although it is suspected to have an immune basis. It may affect the small intestines, large intestines, or both. Vomiting and weight loss are common but do not always accompany the diarrhea.
            
  • Dietary intolerance or allergy is most often attributed to a particular protein in the diet, but can be associated with gluten, lactose, high fat content, and certain food additives. It can develop slowly, over weeks or months and cause chronic diarrhea.

  • Drugs and toxins are more often associated with acute diarrhea; however chronic diarrhea may occur following the administration of certain antibiotics, nonsteroidal anti-inflammatory drugs, certain supplements, etc.

  • Gastrointestinal cancer can cause chronic diarrhea by either destroying part of the intestinal walls or by causing a partial blockage of the intestine. The most common tumors seen are lymphosarcoma and adenocarcinoma.

  • Partial obstruction or blockage may develop with cancer, ingestion of foreign bodies, intussusception (telescoping of the bowel into itself), cecal inversion, or stricture of the intestines.

  • Metabolic disorders including kidney and liver disease, diabetes mellitus, and hypoadrenocorticism, are often associated with systemic signs of illness (e.g. vomiting, weight loss, chronic diarrhea, etc.).

  • Pancreatic disease, especially exocrine pancreatic insufficiency (EPI) gives rise to chronic diarrhea because there is inadequate production of digestive enzymes.

  • Small intestinal bacterial overgrowth (SIBO) is characterized by an overgrowth of normal intestinal flora (bacteria) usually secondary to other gastrointestinal diseases, but occasionally from chronic administration of antibiotics and other medications.

  • Many diseases can cause malabsorption of food stuffs or poor digestion of food stuffs in the intestines, and subsequently chronic diarrhea. Malabsorption/maldigestion problems include lymphangiectasia (abnormality of lymph vessels of the intestines), inactivation or lack of digestive enzymes, inadequate supply of bile salts, severe inflammation of the lining of the intestines, inability to absorb sugars or proteins across the intestinal wall, etc.

  • Short bowel syndrome is created after a large portion of the intestinal tract is removed surgically. The remaining bowel is too short to provide an adequate surface for digesting and absorbing nutrients.

  • Irritable bowel syndrome (spastic colon) is a chronic, intermittent dysfunction of the lower bowel for reasons not entirely understood. This condition may be aggravated by stress.

  • Veterinary care includes diagnostic tests and subsequent treatment recommendations. Some, if not all, of the following tests may be necessary to diagnose the cause of chronic diarrhea:

  • Complete medical history and physical examination are helpful in instituting an appropriate diagnostic plan.

  • Multiple fecal studies (flotation, smear and cytology, zinc sulfate test) to search for intestinal parasites, protozoal parasites, and bacteria should be performed on all patients with chronic diarrhea.

  • A complete blood count (CBC) evaluates the animal for infection, inflammation and anemia.

  • A biochemical profile assesses kidney, liver, and pancreas function, as well as electrolyte status, protein levels, blood sugar, etc.

  • A urinalysis helps to evaluate kidney function and the level of hydration of the animal.

  • Abdominal radiographs (X-rays) assess the abdominal organs and may detect the presence of a foreign body, obstruction, or tumor.

  • Thoracic (chest) radiographs are recommended in geriatric patients and animals who may have cancer, to detect metastasis (spread of cancer) to the lungs.

  • Bacterial fecal cultures may be recommended in some cases.

  • Serologic tests may be performed for fungal diseases that cause chronic diarrhea.

  • Serum trypsin-like immunoreactivity (TLI) , serum folate, and cobalamin are blood tests that help assess digestion and absorption within the small intestines.

    Depending upon the clinical signs and the results of the above tests, your veterinarian may recommend further testing. These tests are chosen on a case-by-case basis:

  • Abdominal ultrasonography helps to evaluate the size, shape and consistency of the abdominal organs. It may detect thickening of the intestines, masses, partial obstructions and other organ abnormalities. Abnormal organs, lymph nodes and masses may be sampled with a needle or biopsy instrument with the guidance of ultrasound. This test may require referral of your animal to a veterinary specialist in internal medicine or radiology.

  • An upper gastrointestinal (GI) barium series helps assess the passage of food stuffs through the upper intestine. A barium enema helps assess the lining of the lower bowel. The two tests may detect motility disorders, thickening of the bowel, twisting or displacement of the bowel, obstructions, strictures and masses of the intestines. They may also be helpful to detect foreign bodies that are not seen on plain radiographs.

  • Endoscopic examination and biopsy are often required for diagnosing the cause of chronic diarrhea. Endoscopy involves passage of a flexible viewing scope into the stomach and small intestines. Colonoscopy involves passage of either a flexible or rigid scope into the rectum and colon. Small biopsies, as well as samples for cytology and culture are obtained through the scope

  • A blood lead level may be performed on any dog with chronic intestinal signs, especially if their environment is suggestive of exposure to lead, if there is material showing up on plain x-rays that resembles lead in the intestines, or if certain characteristic changes of lead poisoning are seen on the complete blood count.

  • Serum bile acid tests may be performed in animals with evidence of liver disease.

  • Exploratory abdominal surgery (laparotomy) is often considered if other diagnostic tests are inconclusive, or if a disease is suspected that requires corrective surgery. It is sometimes needed to reach a conclusive diagnosis.


    Treatment In-depth

    Symptomatic Treatment

    Symptomatic or empirical treatment may be tried in some cases of chronic diarrhea, especially if initial diagnostic tests are inconclusive and the animal is feeling well and relatively stable. Empirical treatment does not replace the need to define the exact cause of the chronic diarrhea, it at all possible. Empirical treatment may include one or more of the following:

  • Deworming for whipworms, which may not show up on routine fecal tests

  • Short course of antibiotics for suspected clostridial bacteria

  • Changing the diet to a high-fiber diet if large bowel diarrhea is present or to a hypoallergenic diet if small bowel diarrhea is present

    Supportive Therapy

  • Supportive therapy for ill, malnourished and unstable patients may involve hospitalization with intravenous fluids, and supplemental nutrition and vitamins.

  • Plasma transfusions and infusion of other dense fluids may be required for animals with low protein levels.

  • Intestinal protectants, adsorbents, and antacids may be administered while results of diagnostic tests are pending, etc.

  • Motility modifiers (medications that effect the movement of food through the intestinal tract) may be tried in some cases.

    Specific Treatments

    Specific therapy of most cases of chronic diarrhea depends upon reaching a definitive diagnosis as to the cause, and then instituting therapy for that cause. Such therapy varies widely and can involve medications, dietary changes and surgery:

  • Deworming agents are required for intestinal parasites.

  • Products used for protozoal parasites include sulfa drugs for coccidiosis and metronidazole for giardiasis.

  • Antibiotics are administered for bacterial infections, small intestinal bacterial overgrowth, and some forms of colitis.

  • Antifungal drugs (e.g. ketoconazole, itraconazole) are given for fungal infections and may be tried for protothecosis.

  • Corticosteroids and dietary manipulation may be necessary for inflammatory bowel disease, lymphangiectasia, and other immune-mediated inflammatory disorders.

  • Dietary manipulation is helpful in cases of dietary intolerance, food allergy, colitis, short bowel syndrome, and irritable bowel syndrome.

  • Chemotherapy, radiation therapy or surgery may be helpful in certain cases of cancer.

  • Surgical exploratory is indicated to correct causes of chronic obstruction, intussusception, cecal inversion, remove foreign bodies, etc.

  • Intravenous fluid therapy and specific treatments for any liver and kidney disorders may be indicated.

  • Pancreatic enzyme replacement therapy is necessary in documented cases of exocrine pancreatic insufficiency.

  • Motility modifiers (medications that effect he movement of food through the intestinal tract) may be helpful in cases of irritable bowel syndrome.

  • Supplementation with cobalamin, folate and other vitamins is often required in the malabsorption/maldigestion diseases.

  • If lead poisoning is diagnosed antidotes may be started either orally or by injection.

    Home Care

    Keep in mind that the resolution of chronic diarrhea is usually gradual with treatment. In a few cases, despite a correct diagnosis and proper therapy, diarrhea may not completely resolve or may worsen, especially in patients with cancer.

    It is important to monitor your pet closely if he has chronic diarrhea. Pay particular attention to stool volume and character, the frequency of defecation, and any straining to defecate. Note the presence of any blood or mucus in the stool. Also monitor the dog's body weight, appetite and activity level.

    Administer all prescribed medications exactly as ordered by your veterinarian. Notify your veterinarian if you have any problems medicating your pet.

    Repeated follow-up examinations, fecal tests and blood tests may be needed to bring the chronic diarrhea under control and prevent it from returning.

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