217. Impact of Meat-based Raw versus Thermally Processed Diets on Serum Metabolites and Plasma Concentrations of Advanced Glycation End Products in Healthy Dogs.

Abstract Studies in rodent models suggest that high circulating concentrations of advanced glycation end products (AGE), including methylglyoxal-derived hydroimidazolone (MG-H1) formed during thermal processing, may contribute to the development of chronic disease. We hypothesized that meat-based pet foods subjected to high-heat processing have greater AGE concentrations than raw pet food, and that these differences are reflected in plasma AGE concentrations in dogs. Eleven healthy adult Beagles [4.5 yr; 11.5 ± 2.0 kg] were enrolled in a three-period (45-d each) incomplete Latin square design study, separated by 14-d washout periods. Dogs were fed one of three diets to maintain body weight (BW): a commercial complete and balanced raw diet (RAW), the RAW diet retorted (targeted lethality value of 10; CANNED), or a commercial complete and balanced canned diet with similar macronutrient composition (CANNED_COMMERCIAL). Based on the analyzed vitamin content of RAW and CANNED, a custom vitamin premix was created and top-dressed onto the CANNED diet during the feeding trial to target similar vitamin intakes between RAW and CANNED groups. Fasted and 2-h postprandial blood samples were collected at baseline and at the end of each period. Diets and plasma were analyzed for 10 specific AGE via high-resolution LC-MS/MS after enzymatic hydrolysis. Serum biochemistry profile was assessed in fasted samples. Data were analyzed using the GLIMMIX procedure (SAS v 9.4) in a repeated-measures model with diet, time and diet×time as fixed effects, square, period and dog(square) as random effects, and baseline as a covariate when applicable. The RAW diet had the lowest concentrations for 7 of the 10 analyzed AGE. Notably, dietary MG-H1 was lowest in RAW (2.9 mg/1000 kcal ME), followed by CANNED_COMMERCIAL (24 mg/1000 kcal ME) and CANNED (54 mg/1000 kcal ME). Similar (P < 0.05) results were found for dietary concentrations of carboxyethyl-arginine (CEA) and carboxyethyl-lysine (CEL). Dogs maintained (P > 0.05) BW throughout the study, and food intake did not differ (P > 0.05) among dietary treatments. Reflecting dietary AGE intake, a diet×time interaction effect was observed (P < 0.05) for plasma MG-H1, CEA and CEL concentrations, with dogs fed canned diets having greater fasted levels and greater postprandial increases than those fed RAW (P < 0.05). While plasma pentosidine, glucosepane, and fructosyl-lysine concentrations were not impacted by diet (P > 0.05), dogs fed CANNED had greater (P < 0.05) plasma glyoxal-derived hydroimidazolone and methylglyoxal-lysine dimer concentrations postprandially compared to those fed RAW (P < 0.05). Additionally, dogs fed RAW exhibited lower plasma cholesterol (P < 0.05) and a tendency toward lower alkaline phosphatase (P = 0.0996) than those fed CANNED and CANNED_COMMERCIAL. In summary, dogs fed RAW had lower circulating AGE concentrations than those fed thermally processed diets. Further research is needed to investigate how differences in circulating AGE levels impact long-term health and metabolism of healthy dogs.