Inflammatory bowel diseases (IBD) are common gastrointestinal disorders in humans and companion animals such as dogs and characterized by chronic periods of exacerbation and remission. Dietary and microbial antigens are the most common environmental factors involved with IBD development. Two main aspects of relationship between nutrition and IBD include nutritional support for malnourished patients and primary therapy for active disease and maintenance of remission. Up to now, there are no perfect experimental animal models of IBD due to its heterogeneous spectrum of pathological features. Since dogs as large animal models are biologically relevant to humans and because of clinical and mechanistic similarities between spontaneous IBD in dogs and humans, this model must also be used to increase our understanding of the disease process. Study of nutritional supplements in canine spontaneous IBD and comparing the results with findings in humans might offer the possibility to establish a disease model for spontaneous human IBD and hopefully, open a door for treatment trials testing new therapeutic approaches with benefits for canine and human patients.