Benefits of dietary supplements on the physical fitness of German Shepherd dogs during a drug detection training course

Abstract

A high standard of physical fitness is an essential characteristic of drug detection dogs because it affects not only their ability to sustain high activity levels but also their attention and olfaction efficiency. Nutritional supplements could improve physical fitness by modulating energy metabolism, oxidative processes, and perceived fatigue. The aim of this study was to investigate the physiological and biochemical changes induced by submaximal exercise on drug detection dogs (German Shepherd breed) and to assess whether a dietary supplement improves their physical fitness. During a drug detection dog training course, seven dogs were fed with a basal diet (Control Group) for three-month period, while a further seven dogs were fed with a basal diet as well as a daily nutritional supplement containing branched-chain and limiting amino acids, carnitine, vitamins, and octacosanol (Treatment Group). At the end of this period, individual physical fitness was assessed by making each subject take a graded treadmill exercise test. A human heart rate monitor system was used to record the dog's heart rate (HR) during the treadmill exercise and the subsequent recovery period. The parameters related to HR were analysed using nonparametric statistics. Blood samples were collected before starting the nutritional supplement treatment, before and after the treadmill exercise and following recovery. Linear mixed models were used. The dietary supplements accelerated HR recovery, as demonstrated by the lower HR after recovery (P<0.05) and Time constants of HR decay (P<0.05), and by the higher Absolute HR Recovered (P<0.05) recorded in the Treatment group compared with the Control dogs. The supplemented dogs showed the lowest concentrations of creatine kinase (CK; P<0.001), aspartate aminotransferase (AST, P<0.05) and non-esterified fatty acids (NEFA; P<0.01) suggesting a reduction in muscle damage and improvement of energy metabolism. These data suggest that this combined supplement can significantly enhance the physical fitness of drug detection dogs.

Fig 1. Experimental protocol.

Fourteen dogs were randomly divided into two groups: a Control (n = 7) and a Treatment (n = 7) group. The dogs in the Treatment group were fed a dry diet with dietary supplementation for 3 months. At the end of this period, all of the dogs underwent a standardized submaximal treadmill Test conducted at four walking speeds and inclinations. Heart rate was monitored throughout the duration of the test (27 min) and recovery period (30 min). Blood samples were taken before starting the nutritional supplementation treatment (T0), immediately before starting the Exercise Test (T1), within the first 2 minutes after exercise test termination (T2) and at the end of the passive recovery period (T3).

Fig 2. Single dog’s deflection point (HRdp; dashed line) determined via Dmax method (Dog n° 12).

For each dog, a third order curve was calculated by plotting heart rate (HR) values vs time (during the incremental exercise phase); two end points of the curve were connected by a straight line and the most distant point of the curve to the line (Dmax) was considered as the HRdp.

Fig 3. Single dog’s time constants of the post-exercise HR decay (τ20; Dog n° 7).

The τ20 was determined starting from the slope of the regression line obtained by plotting the natural logarithm of the heart rate (HR) vs time (during the first 20 min of recovery).