Effects of a human-grade dog diet on gene expression, skin and coat health measures, and fecal microbiota of healthy adult dogs

Geary, Elizabeth L.

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https://hdl.handle.net/2142/115596 Copy

Description

Title

Effects of a human-grade dog diet on gene expression, skin and coat health measures, and fecal microbiota of healthy adult dogs

Author(s)

Geary, Elizabeth L.

Issue Date

2022-04-27

Director of Research (if dissertation) or Advisor (if thesis)

Swanson, Kelly S

Committee Member(s)

• de Godoy, Maria R. C.
• Fahey, George C.

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• human-grade
• dog
• canine
• nutrition

Abstract

Human-grade pet foods have purported benefits such as reduced inflammation, enhanced coat quality, and improved gut health, but research on this category of pet food is scarce. Therefore, our objective was to compare whole blood gene expression, skin and coat health measures, and the fecal microbiome of dogs consuming a human-grade or extruded kibble diet. Twenty beagles (BW = 10.25±0.82 kg; age = 3.85±1.84 yr) were used in a completely randomized design. The diets tested were: 1) Chicken and Brown Rice Recipe [extruded; Blue Buffalo (BB)]; and 2) Chicken and White Rice [human-grade; Just Food for Dogs (JFFD)]. The study consisted of a 4-week baseline, when all dogs were fed BB, and a 12-week treatment phase when dogs were randomized to either diet (n=10/group). After the baseline and treatment phases, fresh fecal samples were scored and collected for pH, dry matter (DM), and microbiome analysis; blood samples were collected for gene expression analysis; hair samples were collected and imaged using a scanning electron microscope; and skin was analyzed for delayed-type hypersensitivity (DTH), sebum concentrations, hydration status, and transepidermal water loss (TEWL). All data were analyzed as change from baseline using the Mixed Models procedure and SAS (version 9.4). At baseline, fecal pH was higher (p<0.05), circulating basophils were higher (p<0.05), hair surface score was lower (p<0.05; less damaged), superoxide dismutase (SOD) and tumor necrosis factor- (TNF-) expression was lower (p<0.05), and cyclooxygenase-2 (COX-2) expression tended to be lower (P=0.057) in dogs allotted to JFFD. The decrease in change from baseline fecal pH and DM was greater (p<0.05) in dogs fed JFFD than those fed BB but fecal scores were not affected by diet. The increase in change from baseline hair surface score was higher (p<0.05; more damaged) in dogs fed JFFD. This result is likely due to the JFFD group being lower at baseline and then returning to a level more similar to BB. The decrease in change from baseline TEWL in the back region was greater (p<0.05; less water loss) in dogs fed JFFD, but TEWL in the inguinal and ear regions, hydration status, and sebum concentrations in all regions were not affected by diet. Hair cortex scores and DTH responses were not affected by diet. The increase in change from baseline gene expression of SOD, COX-2, and TNF- was greater (p<0.05) in dogs fed JFFD, likely due to the differences at baseline. PCoA plots based on Bray-Curtis distances of bacterial genera and species showed small shifts over time in dogs fed BB, but much greater shifts in those fed JFFD. JFFD increased (adj. p<0.05) the relative abundances of 4 bacterial genera, 11 bacterial species, 68 KEGG pathways, and 167 MetaCyc pathways, and decreased (adj. p<0.05) the relative abundances of 16 bacterial genera, 25 bacterial species, 98 KEGG pathways, and 87 MetaCyc pathways. In conclusion, the human-grade pet food tested had minor effects on skin and coat health measures, and whole blood gene expression, but dramatically shifted the fecal microbiome. Longer studies are likely needed to demonstrate health benefits of such diets.

Graduation Semester

2022-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Elizabeth Geary

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