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

Abstract To evaluate (1) the effects of 3 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. Ten colony cats were included in the study. Baseline measurements were first obtained with cats fed a baseline diet without nutraceutical to validate the effects of 3 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 2 groups to test diet U or US for 5 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. At baseline, open field test and blood sampling induced greater 24-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 24-hour urinary cortisol/creatinine ratio. 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 24-hour urinary cortisol/creatinine ratio, a marker of stress, in cats.