Evaluation of a new prescription diet with lemon balm, fish peptides, oligofructose and L-tryptophan to reduce urinary cortisol, used as a marker of stress, in cats

Abstract Objective : To evaluate (1) the effects of three mild stressors on urinary cortisol - a stress marker - in cats and to evaluate (2) the effects on this parameter of a new prescription diet (diet US) with L-tryptophan, lemon balm, oligofructose and fish peptides compared with a control prescription diet (Diet U) with L-tryptophan alone. Methods : Ten colony cats were included in the study. Baseline measurements were firstobtained with cats fed a baseline diet without nutraceutical to validate the effects of three mild stressors (open field test, overnight fast and blood sampling) on urinary cortisol. Twenty-four-hour free catch urine specimens were obtained under routine management conditions and following application of the three mild stressors. Cats were then randomized in two groups to test diet U or US for five weeks in a crossover design, following the same procedure as for baseline measurements. Twenty-four-hour urinary cortisol/creatinine ratio, serum cortisol and serum serotonin were measured. Results : At baseline, open field test and blood sampling induced greater twenty-four-hour urinary cortisol/creatinine ratio compared to the value obtained under routine management while overnight fasting did not. In the crossover design, compared to diet U, diet US resulted in a lower average twenty-four-hour urinary cortisol/creatinine ratio. Conclusions : Open field test and blood sampling can be considered as mild stressors in cats. Compared to a diet with L-tryptophan alone, a diet supplemented with lemon balm, fish peptides, oligofructose and L-tryptophan resulted in a lower average twenty-four-hour urinary cortisol/creatinine ratio, a marker of stress, in cats.