There is a plethora of scientific research evaluating how food can impact our pup’s intestinal microbiome. An overlooked area is the effects of other microbial communities, such as the skin microbiome. However, new research is emerging that focuses its attention on how food can affect the skin microbiome. In this article, we will explore the skin microbiome and the role of diet.
What is the skin microbiome?
Did you know that the skin is actually the largest organ? It is the first barrier of protection against injury and infection. It does this with the help of microorganisms such as bacteria, fungi, and viruses, collectively referred to as the skin microbiome.
While the skin microbiome in humans has been heavily researched, there is still much to learn about the skin microbiome for our dogs.
Your dog's skin is host to a diverse group of bacteria and the composition varies depending on location. For example, the major bacteria on your dog’s microbiome will differ from those on their paws, ears, armpits, and their belly!
There will also be individual differences depending on environmental factors and, interestingly, health status.
Factors that can affect the skin microbiome of your dog include:
- Climate and seasonal changes
- Other pets in the household
- Genetics or breed
- Your own skin microbiome
- Gut health (i.e. Gut-Skin Axis)
How does health affect the skin microbiome?
A study from 2014 investigated the differences between the skin microbiome of healthy adult dogs compared to the skin microbiome of dogs diagnosed with atopic dermatitis.
The researchers concluded that dogs with atopic dermatitis have lower species richness and diversity in their skin microbiome than healthy dogs.
Other health conditions that may be associated with an altered skin microbiome include:
- Allergies (environmental or dietary)
- Wound infections
- Yeast or bacterial infections
Photo by Angel Luciano
Unfortunately, the role of the skin microbiome and health in dogs has not been heavily investigated. For example, it is not clear yet whether the skin microbiome changes in response to these conditions, or whether the composition of the skin microbiome influences or leads to these conditions. More research is still needed and encouraged!
What is the role of diet and the skin microbiome for dogs?
While the role of diet on the gastrointestinal microbiome has been heavily studied, its effects on the skin microbiome have not been investigated to the same extent. However, we do know that diet can influence skin and coat health.
For example, omega-6 and -3 fatty acids are well known for their role in promoting skin and coat health in dogs. Fatty acids are involved in the skin barrier function and regulating inflammation. Together, the omega fatty acids can help reduce itching, scaling, and redness associated with allergies, while also promoting the production of healthy skin oils that improve coat shine and texture.
In addition, proteins play an important role in skin and coat health in dogs because they are the building blocks of the skin and fur. Proteins are made up of amino acids, which are essential for the growth, repair, and maintenance of the skin and coat.
Photo by Alvan Nee
Cysteine and methionine are sulfur-containing amino acids that are essential for keratin formation (the main structural protein found in the skin, hair, and nails) which provides strength and elasticity to these tissues. Methionine is also involved in the production of natural pigments that give the coat its colour.
The role of proteins in the immune system may also be important in skin health. The skin is a site of many immune reactions, and a healthy immune system is important for protecting the skin from infections and allergies. Proteins are essential for the production of antibodies and other immune cells that help fight off infections and allergens.
In addition to proteins and fats, other nutrients can greatly influence skin and coat health:
1) Zinc: Plays a critical role in the production of new skin cells, and a deficiency in zinc can lead to skin problems such as dryness, scaling, and dermatitis.
2) Vitamin A: Important for the growth and repair of skin cells, and it also helps to regulate the production of natural oils in the skin and hair.
3) B vitamins: Important for maintaining healthy skin and coat, as they help to support the growth and repair of skin cells and promote the production of healthy hair.
4) Vitamin E: A powerful antioxidant that helps to protect the skin from damage caused by free radicals. It also helps to moisturize the skin and promote healthy hair growth.
5) Water: Adequate hydration is necessary to keep the skin moisturized and prevent dryness, flakiness, and itchiness
Photo by Rafael Ishkhanyan
However, whether these nutrients and their effects on skin and coat health impact or alter the skin microbiome has not been investigated. That said, a recent study by Leverett et al., published in Animals, compared the skin microbiome of dogs fed a fresh, gently cooked pet food or an extruded dry kibble.
The study found that the composition of the skin microbiome changed depending on the diet fed. In addition to changes in bacterial diversity and richness, the study also found changes in the types of bacteria present in the skin microbiome of dogs fed the two different diets.
There are many factors that could have played a role in the findings of this study. For example, there were differences in the nutritional make-up of the two diets. The researchers specifically call out zinc, fatty acid profiles, and protein as potential influences on the skin microbiome, due their roles in skin and coat health discussed above.
Due to new research also investigating the connection between the gut and the skin in humans, known as the gut-skin axis, the influence of fibre and diet on the gastrointestinal microbiome may have also impacted the results of this study.
We also must consider the differences between gently cooked dog foods and extruded dry food. For example, understanding that hydration is a key component in skin function and integrity, considerations should be made for the moisture difference in the gently cooked diet compared to that in the kibble diet.
Additionally, the nutrient digestibility of the diets may have had an effect. It has previously been found that gently cooked pet foods may be more digestible than traditional extruded dry foods. You can read more about that study HERE.
Fisherman's Best Friend
New research by Geary et al. from Dr. Kelly Swanson’s lab at the University of Illinois did not find changes in skin and coat health measures when dogs were fed a gently cooked pet food compared to an extruded kibble diet. However, this study did not evaluate the skin microbiome.
In addition, Dr. Swanson notes that this research was limited to healthy adult dogs. To truly identify potential benefits of gently-cooked food on skin health and function, research will need to consider investigating these effects in larger populations, including pups prone to dermatitis and other, similar, conditions.
Of course, this is all preliminary research, but it paves the way for future investigations and identifies key areas for researchers to narrow their focus on. It is also exciting research for us and pet parents who feed gently cooked pet food!
In conclusion, the skin microbiome plays a crucial role in maintaining the health and well-being of dogs. Diet may play an important role in shaping the composition and function of the skin microbiome and feeding dogs a high-quality and balanced diet that is rich in beneficial ingredients may help support a healthy skin microbiome and reduce the risk of skin problems.
Pet owners should consult with their veterinarian to determine the best diet for their dog's individual needs and health concerns.
BSc.H. | MSc. Animal Nutrition
This blog post was reviewed by Dr. Kelly Swanson, PH.D., Animal Nutrition & Nutrigenomics Expert, before publication.
Chermprapai S. et al. 2019. The bacterial and fungal microbiome of the skin of healthy dogs and dogs with atopic dermatitis and the impact of topical antimicrobial therapy, an exploratory study. Veterinary Microbiology, 229:90-99. https://doi.org/10.1016/j.vetmic.2018.12.022
Geary, E. L., et al. 2022. Effects of a mildly cooked human-grade dog diet on gene expression, skin and coat health measures, and fecal microbiota of healthy adult dogs. Journal of Animal Science, 100:1-15. doi: 10.1093/jas/skac265
Hoffman R. et al., 2014. The Skin Microbiome in Healthy and Allergic Dogs. PLOS ONE, 9(1). https://doi.org/10.1371/journal.pone.0083197
Leverett et al. 2022. Fresh Food Consumption Increases Microbiome Diversity and Promotes Changes in Bacteria Composition on the Skin of Pet Dogs Compared to Dry Foods. Animals, 12(15). https://doi.org/10.3390/ani12151881
Oba, P. M. et al. 2020. True nutrient and amino acid digestibility of dog foods made with human-grade ingredients using the precision-fed cecectomized rooster assay. Translational Animal Science, 4:442-451. doi: 10.1093/tas/txz175
Watson T.D.G. 1998. Diet and skin disease in dogs and cats. Journal of Nutrition, 128(12):2783S-2789S.
Weese J.S. 2013. The canine and feline skin microbiome in health and disease. Veterinary Dermatology, 24(1). https://doi.org/10.1111/j.1365-3164.2012.01076.x