Canine Heart Rate Research Articles

Simultaneous Monitoring of Canine Heart Rate and Respiratory Patterns During Scent Detection Tasks

Man-made technological odor detection systems continue to improve but still cannot match the tracking efficiency, mobility, and selectivity in the presence of interfering odors achieved by detector dogs. The reliability of dogs as olfactory detectors does not depend solely on their performance but also on the handler’s skill in interpreting the behavior of the dog that signals the detection of the target odor. We present our efforts on a wireless wearable system combining electrocardiogram (ECG) and an electronic stethoscope for direct monitoring of cardiopulmonary events in dogs toward enabling cybernetic dog–machine interfaces. This is, to our knowledge, the first cyber-physical attempt to simultaneously record heart rate, heart rate variability, and continuous auscultation of respiratory behavior in a wearable form factor during scent-detection tasks. In this paper, we present: 1) a method to automate the detection of sniffing episodes based on power spectral density of the respiratory sounds; 2) proof-of-concept extraction and quantification of the ECG and respiratory sounds features that would enable the discovery of physiological patterns associated to scent-detection tasks; and 3) proof-of-concept correlation of such patterns with the presence/absence of target odors. These contributions pave the way for a novel real-time cybernetic olfactory detection monitoring system to provide decision support for handlers in the field in addition to enabling future computer-sniffing dog interfaces.

Evaluation of Dry Electrodes in Canine Heart Rate Monitoring.

The functionality of three dry electrocardiogram electrode constructions was evaluated by measuring canine heart rate during four different behaviors: Standing, sitting, lying and walking. The testing was repeated (n = 9) in each of the 36 scenarios with three dogs. Two of the electrodes were constructed with spring-loaded test pins while the third electrode was a molded polymer electrode with Ag/AgCl coating. During the measurement, a specifically designed harness was used to attach the electrodes to the dogs. The performance of the electrodes was evaluated and compared in terms of heartbeat detection coverage. The effect on the respective heart rate coverage was studied by computing the heart rate coverage from the measured electrocardiogram signal using a pattern-matching algorithm to extract the R-peaks and further the beat-to-beat heart rate. The results show that the overall coverage ratios regarding the electrodes varied between 45–95% in four different activity modes. The lowest coverage was for lying and walking and the highest was for standing and sitting.

Lack of correlation between canine heart rate and body size in veterinary clinical practice

An association between heart rate (HR) and bodyweight has been reported in dogs and it is common belief that small breeds of dog exhibit higher HR than large breeds. The first aim of this study was to test the null hypothesis that, in veterinary clinical practice, bodyweight does not affect HR measured in healthy dogs. A second objective of this investigation was to assess whether other variables, such as gender, breed morphology, age and demeanour, may have a significant effect on dog's HR measured in a clinical setting. The investigation was performed via two different studies: a retrospective analysis performed on 243 electrocardiogram recordings and a prospective study based on 153 standardised clinical examinations. The two separate studies did not show any significant correlation between HR and bodyweight (P=0.5705 and P=0.4682, respectively). Subject's breed morphology and gender did not appear to affect HR measured under these circumstances. However, dogs under the age of one year seem to have significantly higher HRs than older dogs (P < 0.05). Finally, subject's demeanour was also found to have a significant influence on HR; lower values were recorded in relaxed dogs, and higher rates were documented in excited, nervous dogs (P < 0.05). Normal HR could be erroneously interpreted as bradycardia or tachycardia if bodyweight was to be considered a determinant factor. Instead, HR in healthy dogs undergoing routine clinical examination is related to their demeanour or age, if younger than 12 months, but does not appear to be related to bodyweight.

Heart rate variability and saliva cortisol assessment in shelter dog: Human–animal interaction effects

The aim of this study is to investigate the effects of a human interaction program on shelter dogs and to determine the effect on canine heart rate variability, behaviour, and salivary cortisol levels. Twenty dogs were behaviourally (temperament tests) and clinically (full cardiologic examination) pre-tested and then matched in two homogenous groups. Ten dogs (group A) were submitted to a human interaction program and compared to a control group (group B). The study included four experimental sessions (T0, T1, T2 and T3). At T0 salivary cortisol samples (basal cortisol) were collected from all dogs. After 1 week, all dogs were submitted to the following procedures: electrocardiogram holter monitor unit application and recordings, saliva cortisol sample collection before behavioural test (pre-test cortisol), behavioural test application, and saliva cortisol sample collection after behavioural test (post-test cortisol). The above-mentioned experimental session was repeated every 4 weeks from the beginning of the study (T1, T2 and T3). All dogs were videotaped during all behavioural evaluations. Significant differences ( P < 0.05) between groups A and B were determined for heart rate variability (HRV) frequency domain (5 min analysis): low frequency/high frequency ratio (LF/HF) at T1; LF/HF and standard deviation of time duration between two consecutive R waves (RR interval) of the electrocardiogram (SD RR) at T2; very low frequency (VLF) at T3. Overall behavioural test holter recordings showed statistical differences ( P < 0.05): LF/HF at T1 and T2, total number of interpolated beats and total number of used beats at T3. Behavioural data showed significant improvements in sociability/diffidence and temperament in group A for some tests ( P < 0.05). A significant decrease ( P < 0.05) in salivary cortisol levels between T1 vs T2 and between T1 vs T3 has been reported. HRV and behavioural data reported significant correlations in some tests, as well as cortisol levels and behavioural data ( P < 0.05). These data suggest that human interaction supplement sessions have a positive effect upon the behaviour and they could affect the physiological indicators of animal welfare.

The reinforcing value of physical contact and the effect on canine heart rate of grooming in different anatomical areas

The human-animal relationship frequently involves physical touch, and this may have benefits for both participants. Grooming of horses at the withers has a calming effect on recipients, a phenomenon regularly used to reward horses. No studies on the effect on heart rate of grooming in different anatomical areas have been conducted in dogs, even though they are often given physical contact as a putative reinforcer. Kennelled Greyhounds (n = 16) and guide dogs (Golden Retrievers, Labrador Retrievers and their crosses, n = 12) were stroked for eight minutes using a grooming device in each of four areas in random order. These sites were selected on the basis of their being innervated by the dorsal branches of the spinal nerves, lateral branches of the spinal nerves, ventral branches of the spinal nerves and the caudal nerves. Heart rate measurements were taken every 30 seconds using an ECG recorder. There were no observed differences in the mean heart rate based on the region of the body groomed (p = 0.893), nor was any interaction of any other factor with area of the body significant (all p > 0.5). However, for all dogs, there was a highly significant trend (overall reduction) over time (p < 0.001), and Greyhounds had consistently higher mean heart rates than guide dogs (p < 0.001). Within Greyhounds, groomed dogs had significantly lower mean heart rates than non-groomed animals (n = 8, p = 0.003). That is, grooming had a substantial effect on reducing heat rate, but the area of the body where grooming was conducted was not important. In addition, males had consistently lower heart rates than females (p < 0.001). If having a reduced heart rate is a sign of reduced stress, then we can assume that non-invasive interventions that have this effect are reinforcing. The extent to which all dogs are reinforced by physical contact depends on their socialization and familiarity with personnel. The intrinsic reinforcing value of physical contact for dogs seems likely to be outweighed by its effect as a secondary reinforcer.

Behavioural, saliva cortisol and heart rate responses to different types of stimuli in dogs

Stress parameters that can be measured noninvasively may help to identify poor welfare in dogs that live in private homes and institutions. Behavioural parameters are potentially useful to identify stress, but require further investigation to establish which behaviours are appropriate. In the present study, behaviours were recorded and analysed for signs of acute stress in dogs. Simultaneously, saliva cortisol and heart rate were measured to support the interpretation of the behavioural data with regard to stress. Ten dogs of either sex, different ages and various breeds were each subjected to six different stimuli: sound blasts, short electric shocks, a falling bag, an opening umbrella and two forms of restraint. Each type of stimulus had been selected for its assumed aversive properties and was administered intermittently for 1 min. The stimuli that could not be anticipated by the dogs, sound blasts, shocks and a falling bag, tended to induce saliva cortisol responses and a very low posture. The remainder of the stimuli, which were administered by the experimenter visibly to the dog, did not change the cortisol levels but did induce restlessness, a moderate lowering of the posture, body shaking, oral behaviours, and to a lesser extent, yawning and open mouth. Pronounced increases in the heart rate were nonspecifically induced by each type of stimulus. Heart rate levels normalized within 8 min after stressor administration had stopped. Saliva cortisol levels decreased to normal within the hour. Correlations between behavioural and physiological stress parameters were not significant. From the present results, we conclude that in dogs a very low posture may indicate intense acute stress since dogs show a very low posture concomitant with saliva cortisol responses. Dogs may typically show increased restlessness, oral behaviours, yawning, open mouth and a moderate lowering of the posture when they experienced moderate stress in a social setting. The nonspecific character of canine heart rate responses complicates its interpretation with regard to acute stress.

Histochemical and fatigue characteristics of conditioned canine latissimus dorsi muscle.

To induce fatigue resistance in the latissimus dorsi muscle of the dog in preparation for possible myocardial assistance, eight adult male beagles underwent unilateral electrical stimulation of the thoracodorsal nerve at a frequency of 2 Hz (120 stimuli/min) and 10 Hz (600 stimuli/min) for a 6-week period. The conditioned muscles were compared with their unconditioned contralateral controls by fiber typing, pyrophosphate gel electrophoresis, isometric characteristics, and fatigue rates. At the end of the period of stimulation, the conditioned muscles had a greater percentage of slow-twitch, fatigue-resistant fibers on acid and alkaline stains (100 +/- 0.7% and 83 +/- 15.3%), respectively, than did their contralateral controls (45 +/- 7.6% and 43 +/- 7.0). Pyrophosphate gel electrophoresis revealed an increase in the slow myosin and a decrease in the fast myosin content in the conditioned muscles; the stimulated muscles also demonstrated a slower contraction time (87 +/- 20 msec vs. 57 +/- 17.9 msec), a lower initial tension (4.4 +/- 1.45 kg vs. 7.2 +/- 2.11 kg), and a slower fatigue rate during a 30-minute fatigue test than did their contralateral controls. The muscles stimulated at 2 Hz had fatigue rates similar to those stimulated at 10 Hz, but generally had less diminution in muscle fiber diameters and less interfiber connective tissue. Thus, it is possible to make canine latissimus dorsi muscles more fatigue resistant, and, theoretically, more capable of myocardial assistance by electrical stimulation of the thoracodorsal nerve at a frequency as low as 2 Hz--the natural canine heart rate.

Microcomputer control of canine heart rate through chronotropic drug infusion.

Cardiovascular changes principally take two forms: (a) inotropic or pressure-related changes, and (b) chronotropic or rate-related changes. Although the two are not mutually exclusive in the biofeedback of a normally functioning animal, this work was concerned principally with affecting the heart rate of a dog by infusing a rate-altering drug. The purpose of this project was to design an external heart-rate control system which consisted of a dog, an infusion pump containing a chronotropic drug and an infusion-pump/heart-rate controller. Input to the system was a target heart rate. The feedback element and the system output was the dog's actual heart rate, ideally being driven to that target heart rate by the controller. A microcomputer-based system was used with proportional derivative control to accommodate the inherent plant delay. Through the use of an inline solid-state relay, on/off control was chosen because of (i) the capability to use any type of infusion pump, and (ii) the simplicity of design due to slow animal response. The experimental results have demonstrated success at overriding the dog's own biological feedback network and driving its heart rate to some artificially chosen target.