Chronic diarrhea in dogs can have causes that range from something simple to a complex problem that is difficult to resolve. Optimal support for the latter patients relies on an integrative treatment plan that encompasses the interrelated factors contributing to this often challenging health problem.

Chronic diarrhea can be distressing for both dogs and their caregivers, especially when ongoing episodes occur in the house or at night. To add to the distress, dogs with chronic diarrhea (CD) often experience vomiting, appetite and weight loss, and pruritus. Not surprisingly, moderate to severe CD has been associated with reduced quality of life in dogs.1 Unfortunately CD has a long list of causes and is not specific for diseases of the digestive tract. This means a complete understanding of the potential triggers, diagnostic approaches, and management options is essential. Managing CD in a dog can be as simple as administering an appropriate deworming treatment — or as complex as diagnosing and treating chronic inflammatory enteropathy (CIE). Taking an integrative approach to chronic diarrhea in dogs can be an effective way to deal with this common and often debilitating problem.


Generally, diarrhea is recognized as feces with abnormal consistency and excess water content. Stools can range from soft to liquid, without form. Diarrhea that has been present for three weeks or longer is considered chronic.

Small intestine diarrhea occurs in large volumes with a lack of urgency; the frequency of bowel movements does not always increase. Large intestine diarrhea, on the other hand, tends to occur in smaller volumes with urgency and increased frequency. Mucus and blood may be present. It is also possible for a dog to have mixed bowel diarrhea. All these observations highlight the difficulty in describing diarrhea, but are valuable for facilitating diagnostic and management decisions.


Primary gastrointestinal causes of diarrhea include infectious disease (i.e. intestinal parasites, viruses), mechanical issues (i.e. foreign bodies, chronic intussusception), toxicities, non-infectious inflammatory problems and neoplasia.2 Non-infectious inflammatory problems include food sensitivities, dysbiosis, and idiopathic immune-mediated diseases.

Secondary gastrointestinal disorders include diseases affecting the liver, kidneys, exocrine pancreas, cardiovascular system, central nervous system, and endocrine glands.

The majority of CD cases in dogs result from dysregulated intestinal inflammation, currently termed chronic inflammatory enteropathy (CIE). For perspective, one report found that 90% of canine CD cases were primary enteropathies with the majority having an inflammatory basis (79%). Of those, 66% were food responsive, 23% were idiopathic, and 11% antibiotic responsive. Infectious disease was identified in only 13% of the primary enteropathy cases, followed by neoplasia at 4%. Only 10% of the total cases were diagnosed as secondary in origin.2 A similar pattern of distribution was found in other studies.3,4


Chronic inflammatory enteropathy is common and illustrates important integrative approaches for patients with CD. Diagnosing CIE is a process of excluding other causes of diarrhea. A full workup should be performed, including a complete blood count, chemistry profile, T4, cortisol+/-ACTH stimulation, C-reactive protein, trypsin-like immunoreactivity (TLI), pancreatic lipase immunoreactivity (PLI), folate, cobalamin, vitamin D, fecal flotation, and intestinal parasite antigen/PCR testing. Abdominal ultrasound should be considered to rule out other causes of CD.

It is important to note that a normal abdominal ultrasound does not rule out CIE. This means that for severely affected and poorly responsive patients, endoscopic or surgical biopsies may be necessary. Tests to evaluate the intestinal microbiota have become available and are a valuable part of patient assessment. Note that this process of patient evaluation should also allow for the diagnosis and management of CD that is not CIE (see Figure 1).

Assessing the initial severity of a dog’s CIE, and their response to therapy, is important. The canine inflammatory bowel disease activity index (CIDAI) and the canine chronic enteropathy activity index (CCECAI) are useful tools for this assessment.5,6 They provide composite scores based on parameters like appetite, presence of vomiting, and stool consistency. CCECAI has additional parameters such as serum albumin levels and pruritus.


When the diagnostic workup has been completed, treating the identified cause(s) of primary and secondary enteropathies should begin (see Figure 2).

For example, patients with giardia should receive appropriate therapies. Patients with secondary enteropathies like liver disease should receive supportive care and medications and herbs with hepatic side effects should be discontinued, if appropriate. Dietary considerations need to be incorporated into the support plan; for example, a pancreatitis patient may benefit from a low-fat diet. Dogs with toxicities, foreign bodies, intestinal neoplasia, infectious diseases, or dietary indiscretions need to have these particular issues addressed. Keep in mind that these patients may still benefit from having their inflammatory responses modulated, as discussed below.

Most dogs with CD have a primary gastrointestinal issue with inflammation, and a dysregulated immune response. This means a coordinated, multiprong approach for managing the inflammation is critical. From an integrative perspective, support therapy should be directed at the contributors to intestinal inflammation, such as a disrupted epithelial barrier, dysbiosis, and abnormal mucosal immunity. Gut regulation and stress and anxiety management are also important (see Figure 3). Keep in mind that there is a dynamic interrelationship between these contributors that should be recognized.


Dietary therapy

The majority of CIE patients have a food responsive enteropathy. This means all CIE dogs should be placed on an appropriate limited ingredient diet, a balanced home-prepared diet, or a hydrolyzed diet for at least two to four weeks, then reassessed.4 The selected diet can be continued another two to four weeks if improvement is noted. If it isn’t, the diet should be changed. During the food trial, regular monitoring and other supportive care should be provided as described below. Strict compliance with the specified food is critical. In addition, steps should be taken to manage nutritional deficiencies identified through the workup.

Nutritional supplements

  • Deficiencies of cobalamin and folate have been associated with chronic gastrointestinal disease. Hypocobalaminemia has been reported in 19% to 54% of dogs with CIE.7 These dogs may be predisposed to intestinal inflammation and may have a blunted response to other indicated therapies, such as hydrolyzed diets. Cobalamin is essential for mucosal regeneration and reduction of inflammatory infiltrates. Remember, cobalamin deficiency may result from small intestine disease and/or dysbiosis.8
  • The majority of dogs with CIE have low serum vitamin D levels. Hypovitaminosis D is currently thought to contribute to the initiation of intestinal inflammation, based on the effect vitamin D has on modulating immune responses and inflammation. The severity of hypovitaminosis D correlates with clinical severity based on CIBDAI scoring and the outcome of therapy.9 Ideally, vitamin D supplementation should be based on serum level measurements, due especially to the variability in patient baseline levels and variations in patient ability to absorb orally administered vitamin D. Follow-up serum measurements should be performed at eight- to ten-week intervals to determine if appropriate serum levels have been achieved and hypervitaminosis D avoided.10
  • Support for the intestinal epithelial barrier should be incorporated into the therapeutic plan. This includes the use of glutamine, which plays an important role in the health and metabolism of intestinal epithelial cells. Glutamine promotes intestinal epithelial cell proliferation, has anti-inflammatory effects, and regulates tight junction proteins. The intestine uses about 30% of the body’s total glutamine, and as much as 75% of ingested glutamine.11 In addition, the large intestine epithelial barrier can be supported through microbiota fermentation of soluble fiber and supplements like arabinogalactan. These are used to increase the levels of short chain fatty acids (SCFA), which can improve the integrity of the large intestine epithelial barrier and offer immune modulating effects that promote reduced inflammation.4,12
  • Reactive oxygen species (ROS) and reactive nitrogen species (RNS) can be a major factor in initiating and contributing to the progression of inflammation in the gastrointestinal tract.13 They have direct cell membrane-damaging effects that increase cell permeability, cause DNA damage, and induce apoptosis. In addition, ROS and RNS upregulate genes associated with innate and adaptive immunity in the gastrointestinal tract.14 The intestinal tract is a significant source of reactive species. While some level of reactive species contributes to health, their continuous excess production and inadequate removal can play a notable role in promoting chronic inflammation. The addition of whole food ingredients with antioxidant properties, such as polyphenolic compounds and substances like carotenoids, can be beneficial.14 Polyphenols include flavonoids such as anthocyanins, and nonflavonoids such as stilbenes. Cautious use of food ingredients is warranted to avoid aggravating potential food sensitivities associated with CIE. Improvements in the oxidative status of the gut can lead to beneficial changes in the microbiota.


Herbs like curcumin (Curcuma longa), ginger (Zingiber officinale) and green tea (Camellia sinensis) extracts could be considered for their impacts as antioxidants.14,15 However, many herbs also have anti-inflammatory properties that can help manage inflammation associated with CIE. Herbs such as marshmallow root (Althaea officinalis) have antioxidant properties, anti-inflammatory effects, and the added advantage of providing a protective mucilaginous coating for inflamed mucosa.16 It is important to be aware of the potential side effects of herbs, and manage them accordingly. For example, ginger can have impacts on platelets and clotting, while marshmallow root can interfere with the absorption of medications. Carefully selected Chinese herbs can also be beneficial.


The intestinal microbiota is a complex ecosystem that influences health in numerous ways. Studies show a link between CIE, intestinal dysbiosis, and intestinal inflammation.17 This is likely related to the interaction between the digestive process, ingesta, and microbiota in genetically susceptible individuals.18 A full discussion of the role of microbiota in inflammatory enteropathies, and their management, is beyond the scope of this article. However, brief mention will be made with the intention of focusing on supportive therapy for patients with CD and CIE.

Managing intestinal dysbiosis can be challenging and often requires a multistep approach. Optimally, an evaluation of the microbiota using current molecular sequencing techniques should be done. This will facilitate an understanding of how significant the dysbiosis imbalance is for that patient; identify specific approaches for addressing the imbalance; and provide a way to monitor the impact of therapy on the microbiota. Adjustments to ongoing supportive therapy can be made based on serial evaluation of the microbiota.

Managing dysbiosis includes dietary changes, food additives, the use of probiotics, fecal transfer, administration of prebiotic substances, addition of organisms known to suppress pathogens, and the identification of factors that impact the digestive tract microenvironment. When making changes in the dog’s diet, or incorporating additives to the diet, be aware of potential impacts on food responsive disorders or other clinical conditions and avoid changes that can be problematic. Dietary changes that may be beneficial for altering the microbiota include adding protein toppers and reducing carbohydrates. Increasing fiber can also contribute to needed microbiota changes. Adding food ingredients and herbs with antioxidant properties that contribute to the reduction of ROS and RNS can promote important alterations.

An overwhelming range of choices and recommendations for probiotics is available. Considerations include numbers of colony forming units (CFU), numbers of microorganism species, types of organisms (i.e. soil microbes, animal origin, etc.), and inclusion of prebiotic compounds. Some authorities recommend one to ten billion CFU per day, but this can depend on the individual patient. Select products that give consistent patient results based on clinical response and monitoring of the microbiota. Sometimes, a combination of products is necessary and includes prebiotic substances like fructooligosaccharide (FOS). These substances can aid in selective proliferation of beneficial microbiota organisms, increase production of SCFA, improve the epithelial barrier, and promote anti-inflammatory processes.19

The microenvironment of the gastrointestinal tract can contribute to dysbiosis and have a negative impact on achieving desired changes. While altering the diet, incorporating additives, and using probiotics contribute to changing the microenvironment, it is important to recognize that the microenvironment is also impacted by conditions related to the pH of gastric fluid; the quantity and quality of pancreatic fluid, including digestive enzymes; bile acid secretions; and the regular motility of the digestive tract. Herbs may promote beneficial changes in the microenvironment. For example, milk thistle (Silybum marianum) and dandelion (Taraxacum officinale) can promote increased bile production.

The enteric and autonomic nervous systems have impacts on the microenvironment of the digestive tract through their influence on motility, digestive secretions, the epithelial barrier, and immune regulation. It’s important to address management of the negative factors that reduce or limit their regulatory function. This includes reducing stress and anxiety, treating spinal column misalignment, and using modalities like acupuncture.

Note that the use of antibiotics for patients with CD is being debated. Antibiotics may contribute to long term problems with dysbiosis. Patients that respond to antibiotic therapy may already have significant dysbiosis. However, some patients may need a long course of antibiotics while other integrative support options are being implemented.


The intestinal mucosa should be supported as outlined above, including supplements like glutamine, arabinogalactan, antioxidants, and anti-inflammatory herbs. Managing stress, anxiety, and autonomic imbalances plays an important role in the health of the mucosa and immune regulation.


Chronic diarrhea in dogs can be a complex and challenging problem to resolve. A complete workup and understanding of the precipitating and contributing factors is essential, along with recognizing that the majority of CD patients have a dysregulated immune response that propagates intestinal inflammation. Optimal support for these patients relies on a methodical and encompassing integrative treatment plan. This is especially true because of the interrelated nature of the contributing factors. Serial monitoring and therapy adjustments are also important for optimal success.

Disclosure: The author of this article formulated and clinically evaluated the original 16 Standard Process Veterinary Formulas™ during product development as a paid consultant for Standard Process Inc.® He is not employed by Standard Process Inc.®, derives no financial benefit and has no equity interest in either Standard Process Inc.® or Standard Process Veterinary Formulas™



Dr. Ron Carsten was one of the first practicing veterinarians in Colorado to advocate an integrative approach to patient management. He has lectured on the integrative approach and use of nutritional supplements, published on a range of topics in peer-reviewed journals, taught in a number of college and university programs, was faculty for the NIH National Cancer Institute Molecular Prevention Course, has been involved in research, and is a past NIH National Research Service Award Fellow. As a consultant, he developed the original Standard Process Veterinary Formulas™. Dr. Carsten has an AAS in animal health technology, BS in microbiology, MS in anatomy and neurobiology, and PhD in cell and molecular biology. He is a certified veterinary acupuncturist and canine rehabilitation therapist, and practices integrative veterinary medicine in Glenwood Springs, Colorado.


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