Changes in cardiovascular performance, biochemistry, gastric motility and muscle temperature induced by acute exercise on a treadmill in healthy military dogs
The extrinsic muscles of the canine forelimbs and hindlimbs exhibit differences in excitation with different gaits. The overall pattern shows that the forelimb muscles tend to exhibit a decrease in excitation, whereas excitation in the hindlimb muscles increases in the transition from trotting to galloping (Deban et al., 2012). Military dogs have historically been subjected to selection for physical combat and olfactory search and rescue missions. The breeds of dogs that are generally utilized for military work, such as Pit Bulls, have more muscle mass in their distal limbs compared with sprinting dogs (e.g. Greyhounds; Pasi and Carrier, 2003).
Muscle activity and lesions of the limbs have been investigated using indirect infrared thermography in humans (Al‐Nakhli et al., 2012; Bertucci et al., 2013; Bandeira et al., 2014), but this technique is less widely applied in dogs (Vainionpää et al., 2012). The biomedical application of infrared thermography in veterinary medicine is relatively recent. Infrared thermography provides information on the location of physiological and pathological temperature variations (e.g. changes in microcirculation, inflammation, trauma, metabolism and the efficiency of thermoregulatory systems), but it is unable to provide information on the aetiology of disease (Redaelli et al., 2014). To evaluate muscle effort at the end of physical stress, blood concentrations of creatine kinase (CK), aspartate aminotransferase (AST), lactate and lactate dehydrogenase have been assessed in dogs and humans (Rovira et al., 2008; Romagnoli et al., 2014; Diverio et al., 2016). In humans, thermography combined with assessments of transient elevations of muscular biomarkers is useful for analysing muscle activity (Bandeira et al., 2012, 2014), but this relationship has not been established in dogs.
We recently reported that acute exercise in rats alters cardiovascular and metabolic activity. Metabolic activity can influence gastrointestinal motor behaviour by increasing gastric volume and delaying the gastric emptying (GE) of a liquid meal (Silva et al., 2014). Military dogs are often subjected to strenuous activity that requires high metabolic activity despite the possible gut dysmotility that can be caused by exercise. Military kennels often have dogs of different ages. The aim of this study was to assess changes in cardiovascular function, gastric antral motility and superficial hindlimb muscle temperature that were induced by acute physical exercise in military dogs of different ages.