Decoding dysbiosis

Feature
Article

Discovering its hidden impact on dogs and cats.

Sponsored by Hill's Pet Nutrition

The various microbiomes of dogs and cats are made up of a large number of commensal, nonpathogenic microorganisms. The microbiome functions in a unique symbiotic relationship with the host’s immune system to protect against pathogen invasion and colonization. The microbiome protects the host via multiple mechanisms and metabolic functions. As such, a healthy microbiome is an important determinant of host health and loss of the microbial balance has been associated with a variety of systemic disorders.

What is dysbiosis?

Eubiosis exists when there is a healthy and symbiotic relationship between the gut microbiome and the host. This requires a large, diverse population of microorganisms and an environment that is suitable for them to flourish1. Dysbiosis, on the other hand, occurs when the normal, healthy balance of microorganisms in the gut, oral cavity, skin or other microbiome is disrupted and changes its function2. This imbalance can be caused by many factors including diet, antibiotics and other medications, stress, illness, and even changes in the environment3. In dogs and cats, it is often difficult to determine if dysbiosis is the cause or the result of a disease3. The same microbe can play both a protective or pathogenic role depending on the health status of the animal4. When dysbiosis occurs, there can be a shift in which microbes are present or absent, and/or a change in the function and functional byproducts produced by said microbes. These changes can have effects not only on the GI system, but throughout the entire animal.

Gastrointestinal Issues: Dysbiosis is prevalent in dogs and cats with acute or chronic GI diseases. Because the gut microbiome is involved in many metabolic functions, dysbiosis of the microbiome is associated with elevated inflammatory immune response, increases in pathogenic microbes, degradation of the mucus layer of the intestine and increased localized and systemic inflammation5. Factors contributing to dysbiosis include disrupted secretion of antimicrobial fluids, altered intestinal motility, partial obstructions, breed predispositions (notably in German shepherds and Rottweilers), changes in intestinal pH and oxygen levels, and the presence of blood6,7. Additionally, dysbiosis can be induced by drugs such as antibiotics, NSAIDs, and acid suppressants, as well as dietary changes. One of the most common signs of dysbiosis in dogs and cats is gastrointestinal distress. This can include symptoms such as diarrhea, vomiting, and changes in stool consistency.

Immune System Dysfunction: A healthy gut microbiome plays a crucial role in regulating the immune system. The production of antioxidant enzymes by the gut microbiota is crucial for reducing oxidative stress in cats, thereby boosting immune function and promoting overall gastrointestinal health8. Dysbiosis can disrupt the production of anti-inflammatory metabolites, which can weaken the immune response, making cats and dogs more susceptible to infections and illnesses9.

Behavioral Changes: Recent studies indicate a connection between the gut microbiome and behavior via the gut-brain axis. Dogs with an imbalanced gut microbiome may exhibit anxiety, depression, or aggression. The composition of the gut microbiome has been shown to differ between aggressive and non-aggressive dogs10. Research on the link between behavior changes and dysbiosis in domestic cats is sparse, though one study did show a correlation between gut microbes and the behavioral responses11. 

Obesity and Metabolic Disorders: Emerging research suggests a link between gut microbiome imbalances and obesity in dogs. The gut microbiome, especially that contained in the large intestine, is correlated with energy homeostasis, fat metabolism and obesity12. The microbiome compositions of obese dogs are significantly different from those of healthy controls13. Obese cats have been shown to have a significant reduction in microbial diversity and specific microbe abundance, suggesting potential dysbiosis14.

Skin Problems: Dysbiosis can also affect the skin microbiome. The skin microbiome is unique as it has to contend not only with the host’s immune system, but also with environmental and physiological conditions of the skin. Interestingly, a recent study showed that both breed and environmental factors can influence the skin microbiome in cats15. Another study has shown that a lack of microbial diversity appears to be a factor in the development of allergic skin diseases in cats16. The skin microbiome is known to play an important role in improving epidermal barrier function, antimicrobial production and immune function in cats, and should be studied further to allow for more targeted interventions16.

In dogs, skin microbiome dysbiosis can lead to skin problems, including itching, redness, and hot spots. Multiple studies have shown correlations between atopic dermatitis and cutaneous dysbiosis. Similar to cats, the most common finding in studying the canine skin microbiome is a decrease in bacterial diversity present in atopic dermatitis when compared to healthy controls17.

Diagnosing and treating dysbiosis

Diagnosing dysbiosis in cats and dogs typically involves a combination of clinical signs, medical history, and diagnostic tests. Veterinarians may perform fecal examinations, blood tests, and even advanced techniques like DNA sequencing to assess the composition of the gut, or other, microbiomes. There is an overlap in the dysbiosis patterns of many GI diseases, thus no specific dysbiosis patterns for GI diseases have been described that can be used diagnostically to distinguish among various enteropathies. Several functional biomarkers in GI health and disease in cats and dogs have been identified. Increased serum folate (vitamin B9), decreased serum cobalamin (vitamin B12), increased serum methylmalonic acid and increased fecal ɑ1-proteinase inhibitor (ɑ1PI) concentrations have all been associated with chronic gastrointestinal disease (18). Biomarkers of inflammation such as serum C-reactive protein, serum perinuclear anti-neutrophilic cytoplasmic antibodies, serum 3-bromotyrosine, serum and urinary N-methylhistamine, fecal and serum calprotectin, fecal and serum calgranulin C and serum soluble receptor for advanced glycation end products have been the focus of studies of chronic enteropathy in dogs19. A fecal dysbiosis index (DI) assay is a quantitative polymerase chain reaction assay used to assess the fecal microbiome in individual dogs and cats20. The DI is currently the only validated assay to assess the fecal microbiome and measures the abundance of eight specific bacterial taxa and total bacterial abundance. Assessment of these biomarkers and indices may be useful to identify responses to dietary interventions21. As understanding of the other canine and feline microbiomes advances, we hope this knowledge will enable practitioners to offer more targeted testing and interventions to restore health when dysbiosis occurs.

Conclusion

Dysbiosis of the microbiomes in cats and dogs is a complex and multifaceted issue that can have significant impacts on their health. Continued research aimed at further refining dysbiosis indices and understanding the associated metabolic changes will unlock the potential to utilize pet microbiomes as both diagnostic and therapeutic targets.

References

  1. Lozupone, C., Stombaugh, J., Gordon, J. et al. Diversity, stability and resilience of the human gut microbiota. Nature 489, 220–230 (2012).
  2. Zeng, M. Y., Inohara, N., & Nuñez, G. (2017). Mechanisms of inflammation-driven bacterial dysbiosis in the gut. Mucosal immunology, 10(1), 18-26.
  3. Suchodolski, J. S. (2016). Diagnosis and interpretation of intestinal dysbiosis in dogs and cats. The Veterinary Journal, 215, 30-37.
  4. Stacy A, Belkaid Y. Microbial guardians of skin health. Science 2019; 363: 227-228.
  5. Barko, P. C., McMichael, M. A., Swanson, K. S., & Williams, D. A. (2018). The gastrointestinal microbiome: a review. Journal of veterinary internal medicine, 32(1), 9-25.
  6. Allenspach K, House A, Smith K, et al. Evaluation of mucosal bacteria and histopathology, clinical disease activity and expression of Toll-like receptors in German shepherd dogs with chronic enteropathies. Vet Microbiol 2010;146:326-335.
  7. Kathrani A, Werling D, Allenspach K. Canine breeds at high risk of developing inflammatory bowel disease in the south-eastern UK. Vet Rec 2011;169:635.
  8. Jewell, D.; Jackson, M.; Hall, J.; Badri, D. Feeding microbiome-targeting ingredients increases fecal plant-origin antioxidants and anti-inflammatory compounds, and decreases branched-chained amino acids in cats. Curr. Dev. Nutr. 2020, 4, 690.
  9. Suchodolski, J. S. (2022). Analysis of the gut microbiome in dogs and cats. Veterinary Clinical Pathology, 50, 6-17.
  10. Kirchoff, N. S., Udell, M. A., & Sharpton, T. J. (2019). The gut microbiome correlates with conspecific aggression in a small population of rescued dogs (Canis familiaris). PeerJ, 7, e6103.
  11. Koyasu H, Takahashi H, Yoneda M, Naba S, Sakawa N, Sasao I, Nagasawa M, Kikusui T. Correlations between behavior and hormone concentrations or gut microbiome imply that domestic cats (Felis silvestris catus) living in a group are not like 'groupmates'. PLoS One. 2022 Jul 27;17(7):e0269589. doi: 10.1371/journal.pone.0269589. PMID: 35895662; PMCID: PMC9328509.
  12. Garcia-Mazcorro, J. F., Minamoto, Y., Kawas, J. R., Suchodolski, J. S., & de Vos, W. M. (2020). Akkermansia and microbial degradation of mucus in cats and dogs: Implications to the growing worldwide epidemic of pet obesity. Veterinary sciences, 7(2), 44.
  13. Thomson, P., Santibáñez, R., Rodríguez-Salas, C., Flores-Yañez, C., & Garrido, D. (2022). Differences in the composition and predicted functions of the intestinal microbiome of obese and normal weight adult dogs. PeerJ, 10, e12695.
  14. Ma, X., Brinker, E., Graff, E. C., Cao, W., Gross, A. L., Johnson, A. K., ... & Wang, X. (2022). Whole-genome shotgun metagenomic sequencing reveals distinct gut microbiome signatures of obese cats. Microbiology spectrum, 10(3), e00837-22.
  15. Older CE, Diesel AB, Lawhon SD, et al. The feline cutaneous and oral microbiota are influenced by breed and environment. PLoS One 2019; 14.
  16. Older, C. E., Hoffmann, A. R., & Diesel, A. B. (2023). The feline skin microbiome: interrelationship between health and disease. Journal of Feline Medicine and Surgery, 25(7), 1098612X231180231.5.
  17. Rodrigues HA. The cutaneous ecosystem: the roles of the skin microbiome in health and its association with inflammatory skin conditions in humans and animals. Vet Dermatol. 2017;28:60-e15.
  18. Ing, N. H., & Steiner, J. M. (2024). The use of diets in the diagnosis and treatment of common gastrointestinal diseases in dogs and cats. In Nutrition and Metabolism of Dogs and Cats (pp. 39-53). Cham: Springer Nature Switzerland.
  19. Heilmann RM, Steiner JM. Clinical utility of currently available biomarkers in inflammatory enteropathies of dogs. J Vet Intern Med. 2018 Sep;32(5):1495-1508. doi: 10.1111/jvim.15247. Epub 2018 Sep 17. PMID: 30222209; PMCID: PMC6189362.
  20. Sung, C. H., Marsilio, S., Chow, B., Zornow, K. A., Slovak, J. E., Pilla, R., ... & Suchodolski, J. S. (2022). Dysbiosis index to evaluate the fecal microbiota in healthy cats and cats with chronic enteropathies. Journal of Feline Medicine and Surgery, 24(6), e1-e12.
  21. Rossi G, Cerquetella M, Gavazza A, Galosi L, Berardi S, Mangiaterra S, Mari S, Suchodolski JS, Lidbury JA, Steiner JM, Pengo G (2020) Rapid resolution of large bowel diarrhea after the administration of a combination of a high-fiber diet and a probiotic mixture in 30 dogs. Vet Sci 7:21
© 2024 MJH Life Sciences

All rights reserved.