Chronic Diarrhea In Canine

Chronic Diarrhea In Canine: Causes, Symptoms and Treatment

Chronic Diarrhea In Canine: Causes, Symptoms and Treatment


  • Prolonged alterations in the frequency, consistency, and volume of feces persist beyond three weeks.
  • Manifest in the small bowel, large bowel, or mixed.

Causes of Chronic Diarrhea In Canine


Small bowel

Primary Small Intestinal Disease

  • Inflammatory bowel disease (lymphoplasmacytic enteritis, eosinophilic enteritis, granulomatous enteritis, and immunoproliferative enteropathy of Basenjis).
  • Primary or secondary lymphangiectasia.
  • Neoplasia.
  • Bacterial (Campylobacter jejuni, Salmonella spp., invasive adherent or enterotoxic E. coli, and other enterobacteriaceae).
  • Mycotic infections (histoplasmosis).
  • Algal infections (protothecosis and pythiosis).
  • Parasites (Giardia, Toxocara, Ancylostoma, Toxascaris leonina, Cryptosporidium, and Cystoisospora).
  • Partial obstruction (foreign body, intussusception, or neoplasia).
  • Antibiotic-responsive diarrhea (intestinal microbial dysbiosis).
  • Short bowel syndrome.


  • Exocrine pancreatic insufficiency.
  • Hepatobiliary disease (deficiency of intraluminal bile).


  • Food-responsive enteropathy.
  • Food allergy.

Metabolic Disorders

  • Hepatobiliary disease.
  • Hypoadrenocorticism.
  • Uremic gastroenteritis.
  • Adverse drug responses.
  • Toxins (enterotoxins, aflatoxins, exotoxins, and their association with food poisoning).

Large bowel

Primary Large Intestinal Disease

  • Inflammatory bowel disease (lymphoplasmacytic colitis, eosinophilic colitis, and granulomatous colitis).
  • Neoplasia.
  • Infections (histoplasmosis, adherent invasive E. coli, Prototheca, and pythiosis).
  • Parasites (Trichuris vulpis, Giardia intestinalis, Entamoeba histolytica, and Balantidium coli).
  • Ileocolic intussusception.
  • Cecal inversion.


  • Dietary indiscretion, alterations in diet, food-responsive enteropathy, and foreign material (bones, plastic, wood, or hair).
  • Responsive large-bowel diarrhea.


Irritable bowel syndrome.


Risk factors

Small Bowel

  • Dogs that are of a larger breed, younger in age, and exhibit less severe symptoms are more susceptible to developing food-responsive diarrhea.
  • Several dog breeds (Yorkshire terriers, West Highland white terriers, Rottweilers, and soft-coated wheaten terriers) have a predisposition to develop lymphangiectasia as a sequel to inflammatory bowel disease.

Large Bowel

  • Dietary modifications or lack of adherence, stress, and psychological variables.
  • Granulomatous colitis (invasive adherent Escherichia coli) is observed in boxer and French bulldog breeds (less than three years of age).
  • Pythiosis is frequently observed in larger breeds that exhibit a greater propensity for outdoor activities (roaming and hunting).

Pathogenesis of  Chronic Diarrhea In Canine

  • Secretory diarrhea.
  • Osmotic diarrhea.
  • The permeability has experienced an increase.
  • Abnormal GI motility.
  • Numerous instances entail the amalgamation of various pathophysiologic pathways.


Symptoms (History & Physical Examination) of Chronic Diarrhea In Canine


  • Small bowel diarrhea (normal to increased volume of stool, normal to significantly increased frequency of defecation, weight loss, polyphagia, melena, borborygmus, and occasional vomiting).
  • Large bowel diarrhea (decrease in stool volume, increase in the frequency of defecation, hematochezia and mucus, tenesmus, urgency, dyschezia, flatulence, borborygmus, and vomiting).

Physical Examination

Small bowel

  • Inadequate physical health due to malabsorption, maldigestion, and protein-losing enteropathy.
  • Variable dehydration.
  • Upon abdominal palpation, thickened small bowel loops, can be either diffuse or segmental.
  • This finding is linked with infiltrative disease, abdominal effusion, foreign body, neoplastic tumor, intussusception, or enlarged mesenteric lymph nodes.
  • Rectal palpation does not yield any significant findings.

Large bowel

  • Normal body state.
  • Dehydration (uncommon).
  • Upon abdominal palpation, thickened large bowel, foreign body, neoplastic mass, intussusception, or enlarged mesocolic lymph nodes.
  • Upon rectal palpation, irregularities, rectal masses located within or outside the lumen, rectal strictures, and sublumbar lymphadenopathy.

Diagnosis of Chronic Diarrhea In Canine

1- From History and Physical Examination

2- Diagnostic Procedures


  • Anemia.
  • Severe hypoalbuminemia (<2 g/dL) is linked to unfavorable outcomes.
  • Panhypoproteinemia may exhibit an association with protein-losing enteropathy (PLE).
  • Reactive hepatopathy leads to mild to moderate elevations in liver enzymes, specifically ALT and ALP.
  • Dogs with lymphangiectasia often have low cholesterol because their lymphatic fluid loses cholesterol, making it hard for their bodies to absorb it.


  • Fecal flotation with centrifugation for identifying eggs and parasites.
  • Fecal floatation with ZnSO4 and subsequent centrifugation are suggested for identifying Giardia cysts.
  • Direct immunofluorescence assays or SNAP® testing to enhance the diagnostic yield.
  • Fecal PCR assay is a viable method for identification and detection of Heterobilharzia americana eggs, Cryptosporidia, and various other infectious illnesses.
  • Enzyme immunoassay for detecting histoplasma antigen in serum or urine samples.
  • Pythium is identified through the two serological assays (immunoblot assay and ELISA).
  • Bacteria are cultivated from intestinal tissue or detected by PCR in infected tissues.
  • To rule out the possibility of virus-associated enteritis, this study’s goal is to do serologic screening for FeLV and FIV.
  • Cobalamin is measured to assess potential abnormalities.
  • Subnormal levels indicate exocrine pancreatic insufficiency, severe illness affecting the mucosa of the ileum, and intestinal dysbiosis.
  • Correlation between severe hypocobalaminemia (serum cobalamin level below 200 picograms per milliliter) and unfavorable prognosis.
  • Exocrine pancreatic insufficiency is associated with decrease in trypsin-like immunoreactivity (TLI).
  • Pancreatitis results in an elevation of canine pancreatic lipase immunoreactivity (spec cPL).
  • Fecal alpha-1-proteinase inhibitor assay for the identification of protein-losing enteropathy.
  • Canine microbiota dysbiosis index is measured through PCR on fecal samples.
  • Canine calprotectin in blood and feces is a valuable biomarker for dogs with chronic diarrhea.
  • Fecal calprotectin differentiates between enteropathies that are responsive to diet, antibiotics, and steroids.
  • It has been proven that having high levels of perinuclear antineutrophil cytoplasmic antibody (pANCA) is linked to chronic enteropathies, especially those that are triggered by food.
  • Atypical Addison’s disease results in the manifestation of chronic gastrointestinal symptoms that exhibit a waxing and waning pattern.
  • A cortisol level greater than 2 µg/dL excludes the presence of hypoadrenocorticism.
  • If the resting cortisol level is less than 2 µg/dL, conduct an ACTH stimulation test in order to evaluate the adrenal glands’ capacity to respond adequately to stimulation.
  • Thyroid testing to assess the presence of hyperthyroidism in cats and hypothyroidism in dogs.
  • Bile acids are utilized for the detection of hepatobiliary illness.
  • Abdominal X-rays can show nothing wrong or show signs of pancreatitis, partial intestinal obstruction, masses, foreign bodies, organomegaly, hepatobiliary illness, and/or effusion.
  • Thoracic radiographs exhibit no notable abnormalities, although they reveal metastatic illness or pleural effusion associated with protein-losing enteropathy (PLE).
  • Abdominal ultrasonography permits the comprehensive evaluation of all organs within the abdominal cavity.
  • Measurement of intestinal wall thickness lacks sensitivity and specificity as a diagnostic indication for chronic enteropathies.
  • Echogenicity of the intestinal mucosa is a precise biomarker of inflammatory illness.
  • Identification of hyperechoic striations in the duodenum or jejunum indicates protein-losing enteropathy.
  • Identification of hyperechoic speckles in the duodenum or jejunum indicates inflammatory illness.
  • Ultrasound guidance in the fine needle aspiration of gastrointestinal mass lesions for diagnosis of mast cell tumors, carcinomas, and large cell lymphoma.

3- Differential Diagnosis

  • Diet-responsive enteropathy.
  • Antibiotic-responsive enteropathy.
  • Infectious agents (Giardia, histoplasmosis, feline leukemia virus, feline immunodeficiency virus, Pythium, and helminths).
  • Neoplasia (lymphoma, carcinoma, leiomyosarcomas, and mast cell tumors).
  • Inflammatory bowel disease.
  • Lymphangiectasia.
  • Mechanical blockage.
  • Irritable bowel disease.
  • Exocrine pancreatic insufficiency.
  • Pancreatitis, atypical Addison’s, hypothyroidism, hyperthyroidism, renal disease, liver disease (portosystemic shunt), or congestive heart failure.

Treatment of Chronic Diarrhea In Canine


  • The management of chronic diarrhea resulting from infectious illnesses or secondary enteropathies necessitates appropriate medical intervention.
  • Dietary intervention studies are employed for diagnosing food-responsive enteropathy.
  • Antibiotic trials identify cases of antibiotic-responsive enteropathy.


  • Antibiotic-responsive enteropathy: metronidazole (10–15 mg/kg orally every 12 hours) or tylosin (25 mg/kg orally every 12 hours) for a minimum duration of 10 days.
  • Immunosuppressive or steroid-responsive enteropathy: prednisolone or prednisone (0.5–1 mg/kg orally every 12–24 hours), or cyclosporine (5 mg/kg orally every 24 hours).
  • When dogs with chronic diarrhea take fiber supplements, their fecal microbiota changes, making their microbiota profile more like that of healthy dogs.

Some Notes:

Anticholinergics worsen the condition in many cases of chronic diarrhea.


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