Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Comparative and Experimental Medicine

Major Professor

Angela L. Witzel

Committee Members

Joseph W. Bartges, Michael B. Zemel, Stephen A. Kania, Amy K. LeBlanc


Obesity is the most common nutritional disorder of pet dogs (prevalence of 23–59%). This 29-week study investigated a nutraceutical containing 1 g leucine and 13 mg pyridoxine designed to maintain lean muscle mass while decreasing adiposity when compared with positive and negative controls. After determining individual maintenance calorie requirements over 3 – 4 weeks, thirty-six healthy adult Beagles were divided into obesification, weight gain prevention, or maintain ideal body weight arms.

Obesity was induced and during a weight loss phase, excess calories were removed, and obesification dogs were given nutraceutical with CAD (ObN), placebo with CAD (ObP), or a therapeutic weight loss diet (WLD). Weight gain prevention dogs were fed CAD at levels in excess of what they would naturally consume in a single meal with nutraceutical (ExN) or placebo (EXP), and dogs maintaining ideal body weight (IBW) were fed CAD to individual maintenance calories requirements over 12 weeks.

Based on MANOVA, ObN and WLD lost similar levels of total weight (3.4 +/- 0.6 vs. 4.4 +/- 1.1 kg) and fat mass (3.1 +/- 0.6 vs. 3.9 +/- 0.8 kg) after 12 weeks of treatment, and more than ObP (1.2 +/- 1.0 kg weight; 0.9 +/- 1.0 kg fat; p < 0.0001). ExP and ExN gained similar levels of weight and fat mass (up to 32.5 +/- 3.3 vs. 35.7 +/- 6.3% body fat). Behavioral indicators of medium term satiety did not differ clinically between groups. In general, plasma levels of gut hormones and endocrine factors followed expected trends and there was little effect of treatment on muscle or adipose tissue expression of genes involved in fat oxidation, oxidative phosphorylation, and mitochondrial biogenesis. Circulating plasma concentrations of IL6 and IL15 did not differ between groups.

These data show the nutraceutical holds promise as an option for successful weight loss in dogs. Maintenance levels of CAD were able to induce weight loss without risk of hypo- or anorexia, or the need to switch diets or restrict energy intake.

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