FASEB J. 18: Abstr. 269.5.
The objective of this experiment was to determine the effects of age and diet on immune cell populations and CD markers in dogs. Twelve geriatric (age = 11 yr-old at baseline) and 12 weanling (age = 8 wk-old at baseline) beagles were randomly assigned to one of two dietary treatments and remained on study for 12 months. An animal product-based diet was compared with a plant product-based diet. Blood samples were collected at baseline and after 3, 6, 9, and 12 months on study. Immune characteristics at baseline and over time (differences from baseline) were analyzed using the Proc ANOVA and Proc Mixed procedures of SAS, respectively. At baseline, young dogs had greater (P < 0.05) total white blood cell (WBC), neutrophil, and lymphocyte concentrations than old dogs. Age also had a significant effect (P < 0.05) on these immune cell populations over time. As a percentage of total WBC, young dogs had a higher (P < 0.05) proportion of lymphocytes and lower (P < 0.05) proportion of neutrophils compared to old dogs at baseline, a relationship that did not change over time. Although not different at baseline, CD8+ cells tended to be greater (P = 0.09) in young dogs vs old dogs when analyzed over time. These results illustrate the changes observed in canine immune cell populations over the first year of life and highlight the decline in the immune status of geriatric dogs. This research was supported by Pyxis Genomics, Inc.