Serum Metabolomics of Senior Dogs Fed a Fresh, Human-Grade Food or an Extruded Kibble Diet

Background/Objectives: Despite the growing popularity of fresh food for dogs, there is an extremely small amount of literature evaluating the potential health benefits of fresh food and reduced processing compared to traditionally processed shelf stable cans, extruded kibble, or other food formats. Additionally, aging dogs have been previously documented to have altered metabolism and nutritional needs compared to a healthy adult dog population, but these differences are not well defined. The objective of the study was to compare the effects of feeding a fresh, human-grade food versus a standard extruded kibble diet in a year-long longitudinal study on serum metabolomic profiles in senior dogs. Methods: Twenty-two healthy mixed-breed geriatric Alaskan sled dogs were age- and sex matched into two feeding groups. All dogs were fed the extruded diet (control) for a 4-month washout period prior to being transitioned into their respective treatment group. Group 1 continued to be fed the control diet, while Group 2 was transitioned to a fresh, human-grade food (treatment). Body weight and body condition were assessed monthly, and calorie intake was adjusted to maintain body weight. Individual serum samples were collected at day 0 and months 1, 3, 6, and 12. Metabolomic profiling of serum samples was performed by Metabolon, Inc. (Durham, NC, USA). Data was analyzed using two-way analysis of variance with repeated measures to determine treatment differences. Results: Dogs fed the treatment food had an increase in branched-chain amino acid metabolism, creatine, carnosine, anserine, fatty acid metabolism, long-chain n-3 fatty acids, lipolysis, and ketogenesis. The treatment group had decreased advanced glycation end products, fatty acid synthesis, and creatinine. Conclusions: This study is the first long-term feeding study evaluating serum metabolomics in dogs that demonstrates the dramatic and sustained impact that diet can have on canine metabolism.