Feeding fresh food increases microbiome diversity on canine skin, known to improve skin conditions.

Feeding fresh food increases microbiome diversity on canine skin, known to improve skin conditions.

Published article:
https://doi.org/10.3390/ani12151881
Fresh Food Consumption Increases Microbiome Diversity and Promotes Changes in Bacteria Composition on the Skin of Pet Dogs Compared to Dry Foods

Where and When:
Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA

Animal Science Department, California Polytechnic State University, San Luis Obispo, CA 93407, USA
Published July 2022 in the Animals Journal
60 day Dietary Intervention Study
Authors: Kennedy Leverett, Rodrigo Manjarin, Erica Laird, Diana Valtierra, Tasha M . Santiago-Rodriguez, Renan Donadelli, Gerado Perez-Camargo

Question in research: The objective of this study was to evaluate if diet can change the bacteria on the skin of healthy dogs.

Study Participants: 8 Healthy Neutered Adult dogs, aged from 8 months to 8 years, 2 Female and 6 Male.
All previously always fed commercial extruded food and without yeasty microbiome present on their skin at the trial start.
Housed in their home environment in order to represent the environment dogs will more likely live in day to day. Some treats were allowed, following the study guidelines, set out by AAFCO guidelines set for all studies that make up the Complete diet guidelines for pets foods.

What they did:
All dogs were fed the Freshpet Select Sensitive Stomach and Skin roll (steam cooked for approximately 15 min at 100 ◦C) for 30 consecutive days,
They were then fed their regular dry food diet (processed, extruded) for an additional 30 consecutive days.
A 4-day transition period was implemented to switch diets, during which 25% of the fresh food was replaced by the extruded dry food each day.

What was measured:
DNA and RNA extraction from microbiome sample swabs.
Swab samples were taken from the internal ear, the interdigital area of the front paw, and the groin area after the 30-day feeding of each diet. Dogs were not bathed or wiped for a week before each swab, dogs were not allowed to lick the areas prior to each swab either.
Appropriate data processing and statistical methods were used.
1 dog did not complete the study due to anti-biotic use during the 60 days.


Findings:
The data provided evidence of a 60% average difference between the different bacteria types after the two diets.
Contributing to an overall 70% difference in variety of microbiome between the two.

Staphylococcus, Porphyromonas, Streptococcus, Corynebacterium, Conchiformibius, and Pseudomonas were the most dissimilar between the two” so less variety encouraged from the dry extruded diet.
The extruded dry, increased Hymenobacter, Acinetobacter, Neisseria, Stenotrophomonas and Janthinobacterium and decreased Actinomycetospora, Massilia, Bacteroides, average percentage relative counts of Hymenobacter, Acinetobacter, Neisseria, Stenotropho-Spirosoma, Mycoplasma, Jonesia, DA101, Sporosarcina, and Actinotelluria

“When considering the 3 different skin sites, the groin had a higher population of Firmicutes compared to the other sites and the paw had higher proportions of Cyanobacteria and Planctomycetes (p < 0.05). The most common genera among the different skin sites and diets were Staphylococcus, followed by Porphyromonas, Streptococcus, Corynebacterium, and Conchiformibius”

Zinc was higher in the extruded food, a mineral used daily by the internal digestive ‘skin’, the epithelial lining, for renewal processes alongside the microbiome.
This also indicates other aspects of the fresh food are related to microbiome diversity, despite extruded food manufacturers making claims on the Zinc inclusions they include as beneficial synthetic inclusion.

The fresh food had higher concentrations of fatty acids, including Poly-unsaturated fatty acids and DHA. It did however have a slightly lower Omega 3 content on average.
In past studies we have seen how the PUFA’s have contributed to butyrate levels, and those butyrate levels have been attributed to microbiome diversity. Its is likely the same occurrence is happening here too.

Results:
“In conclusion, changing from a fresh diet to a dry extruded promoted a decrease in skin microbiome relative abundance in dogs.
Nevertheless, future research should evaluate the water balance, the colonic microbiome, and the immune system when analysing the skin microbiome, since these factors may have an impact the skin bacteria populations.

It would be safe to assume that the higher proportion of soluble fiber in fresh diet would stimulate fermentation and bacterial growth in the colon when dogs were fed this diet. This increase in bacteria populations and production of fermentation products could stimulate the immune system and promote changes on how the skin would react to different bacteria.

Do the results show skin benefits from the bacteria and diversity created on the fresh diet?

Hymenobacter, Acinetobacter, Neisseria, Stenotrophomonas, which the extruded food was measured to increase are in general considered pathogens, many are involved with infections.

Staphylococcus, Porphyromonas, Streptococcus, Corynebacterium, Conchiformibius were less varied following the extruded diet. These are useful bacteria, spoken of as the healthy canine skin bacteria (4)
“The predominant bacteria on healthy canine skin were Porphyromonas, Staphylococcus, Streptococcus, Propionibacterium, Corynebacterium”
(Text from a different study, referenced below)

In a study that evaluated the skin microbiome of healthy and allergic dogs (1),  the diversity of the bacterial population was lower in allergic dogs compared to healthy dogs.

The skin microbiome of dogs with atopic dermatitis was reported to have less diversity and higher relative concentrations of Staphylococcus (especially S. pseudintermedius) and Corynebacterium compared to healthy dogs. (2)”

The amount of Corynebacterium bacteria was higher in dogs fed the extruded , Staphylococcus bacteria was lower.
This is where the species becomes important. It is known for instance that in humans, Staphylococcus epidermidis can prevent the colonization of a more un-useful bacteria Staphylococcus aureus. (3)
The body is an organism known to be predominantly made up of bacteria, and microbiome. The diversity of the different types within a species is a major factor in the health of the internal skin, and the external skin.

Whilst the study was funded by a fresh pet food company, with a little research on the honest measurements and results we can conclude that the skin bacteria present following the fresh food diet was beneficial. However, further study if the types bacteria more prevalent in the dog’s skin following the feeding of the fresh food would need to be determined.

By Caroline Griffith

1 Hoffmann, A.R.; Patterson, A.P.; Diesel, A.; Lawhon, S.D.; Ly, H.J.; Stephenson, C.E.; Mansell, J.; Steiner, J.M.; Dowd, S.E.; Olivry, T.; et al. The Skin Microbiome in Healthy and Allergic Dogs. PLoS ONE 2014, 9, e83197
2 Bradley, C.W.; Morris, D.O.; Rankin, S.C.; Cain, C.L.; Misic, A.M.; Houser, T.; Mauldin, E.A.; Grice, E.A. Longitudinal Evaluation of the Skin Microbiome and Association with Microenvironment and Treatment in Canine Atopic Dermatitis. J. Investig. Dermatol. 2016, 136, 1182–1190
3 Iwase, T.; Uehara, Y.; Shinji, H.; Tajima, A.; Seo, H.; Takada, K.; Agata, T.; Mizunoe, Y. Staphylococcus epidermitis esp inhibits Staphylococcus aureus biofilm formation and nasal colonization. Nature 2010, 465, 346–349
4 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4877200/ Longitudinal evaluation of the skin microbiome and association with microenvironment and treatment in canine atopic dermatitis.