Development of a perceived exertion scale in dogs exercising on a land treadmill using selected physiologic parameters
Physical rehabilitation therapy is rapidly becoming an integral component in the treatment of a variety of neurologic and orthopedic conditions in veterinary patients. However, to date there are no perceived exertion scales (PES) available for monitoring dogs or for developing exercise protocols. The purpose of this study was to develop a perceived exertion scale for dogs walking/running on a land treadmill using the following physiologic parameters: heart rate, respiratory rate, rectal temperature, blood lactate and glucose concentrations, and regional tissue oximetry. We hypothesized that the measured physiologic parameters would correlate with the perceived exertion of the dogs exercising on a land treadmill and that there would be no difference between intra- and inter-observer perceived exertion of dogs while walking/running on a land treadmill. An additional aim was to compare heart rate obtained from a Holter monitor to those obtained manually and using a mobile ECG monitor. Fifteen healthy client-owned dogs were enrolled in this prospective clinical trial. Each dog participated in two 55-minute exercise trials separated by a one-week recovery period. An initial complete blood count, biochemical panel, urinalysis, total T4, and venous blood gas (including lactate) were performed prior to beginning each trial. Subsequent venous blood gases were obtained after 20 minutes of exercise, immediately after completion of exercise, and after a 20-minute recovery period. Additional physiologic parameters recorded included heart rate, rectal temperature, respiratory rate, and regional tissue oximetry. The perceived exertion was recorded during each trial at 2 minute intervals by a Certified Veterinary Technician, who is also a Certified Canine Rehabilitation Practitioner. Additional perceived exertion scores were recorded via video recording by two veterinarians, a rehabilitation therapy volunteer, and a veterinary student to determine inter-observer variation. The results of the first trial were also compared to the second trial to evaluate for repeatability. Thirteen of 15 dogs completed both trials. Spearman correlations for both trials were positive between Holter heart rate and KardiaMobile heart rate (r = 0.7, p <0.0001), manual heart rate (r = 0.64, p <0.0001),), respiratory rate (r = 0.27, p = 0.019), and temperature (r = 0.29, p = 0.014). Holter heart rate was positively correlated with PES scores from all observers for both trials (p <0.001 for all). The mean PES score recorded by each observer was 2 out of 4 for both trials. To test the assumption that physiological measurements changed with PES score, each dog’s time 0 value was subtracted from subsequent values for that dog and least trimmed squares regression was then used to remove outliers. Outlier-free linear regression estimates were then obtained as follows. For Trial 1 glucose (g/dL) = -2.581 – 2.112 PES (R2 = 0.179, F(1,45) = 9.787, P=0.003). That is, glucose decreased 2.112 g/dL for each incremental increase on the PES. For Trial 2 cutaneous oximetry, rSO2 (%) = 79.118 – 0.924 PES (R2 = 0.059, F(1,171) = 10.639, P=0.001). In Trial 2, baseline-adjusted rSO2 decreased 0.924 percent for each incremental increase on the PES. For Trial 2 respiratory rate (breaths/min), RR=20.640 + 32.600 PES (R2 = 0.114, F(1,48)=6.205, P=0.016). Adjusted respiratory rate increased by 32.6 breaths/min for each incremental increase on the PES. The relationship of PES and temperature (F) in Trial 2 was F= 0.153 + 0.273 PES (R2 = 0.215, (F(1,45) = 12.305, P=0.001). The adjusted temperature increased by 0.273F for each incremental increase on the PES. For all possible pairwise comparisons of PES scores for both trials combined, the Kruskal-Wallis test and repeated measures ANOVA were significant (p < 0.001). In both analyses, most tests between STUDENT and another observer were significant. The overlap of distributions for pairs of PES groups ranged from 92.3% for DVM2 versus TECH down to 64.2% for DVM1 versus STUDENT. No significant differences were noted between Holter, KardiaMobile, and manual heart rates in either trial. The distributions of approximate medians for KardiaMobile and manual heart rates were 96 bpm, and Holter heart rate was 106 bpm with an OVL of 76%. In both trials, the means of the logarithms of heart rates for manual differed from KardiaMobile and Holter. The results of this study demonstrate consistent and repeatable use of a PES for monitoring dogs exercising on a land treadmill. Correlations were consistent between the PES and expected changes in the measured physiologic parameters. The proposed scale may be useful when incorporated as part of the overall monitoring system for canine patients undergoing physical rehabilitation therapy; however, it must be further validated before clinical application. A limitation of this study is that dogs were not exercised to the point of maximal exhaustion.
Canine rehabilitation therapy, Perceived exertion scale
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign