Beyond the lungs and heart: a possible association between digestive disease and exercise intolerance in 10 dogs

Introduction Exercise intolerance and panting are classically attributed to cardiac, respiratory, or other diseases. In some cases, the underlying etiology remains undetermined despite a comprehensive diagnostic workup. While fatigue is one of the most common symptoms in humans with inflammatory bowel disease (IBD), chronic enteropathy is not currently recognized as a primary cause of exercise intolerance in dogs. Methods A retrospective review was conducted on the medical records of 10 dogs presenting with exercise intolerance lacking overt digestive or respiratory signs. All dogs underwent empirical gastrointestinal-directed medical and dietary therapies with subsequent owner-perceived clinical resolution. Results Ten dogs presenting with chronic exercise intolerance were evaluated. Six of these dogs also exhibited unexplained panting at rest (6/10). Subtle gastrointestinal signs and abdominal discomfort on palpation were present in four and five cases, respectively. Standard cardiopulmonary and metabolic investigations were largely unremarkable. Notably, half of the cohort (5/10) exhibited cobalamin insufficiency or deficiency. Dogs were managed with gastrointestinal-directed medical therapies (e.g., prokinetics, acid suppressants, tylosin) and/or dietary modifications (predominantly low-fat, single-protein (monoprotein), or hydrolyzed diets). Following these targeted interventions, all dogs achieved complete clinical resolution per owners within a median of 21 days. Conclusion A gastrointestinal etiology may be considered in dogs presenting with unexplained exercise intolerance and excessive panting. Subtle physical exam findings, serum cobalamin and folate concentrations, and empirical dietary/medical trials can be used to support clinical suspicion. This case series suggests a potential canine equivalent of human IBD-related fatigue, highlighting the need for further research into the gut-brain axis, intestinal dysbiosis, and delayed gastric emptying in veterinary medicine.