Reliability of a New Bite Force Measure and Biomechanics of Modified Long Attack in Police Dogs

SIMPLE SUMMARY: Information on the biomechanics of police dogs’ tasks is important in preventing, diagnosing and treating their work-related injuries and dysfunctions. Despite the fact that dogs in several fields of service are performing protective tasks, there is lack of information regarding the occupational physical demands these dogs are subjected to. This study aimed to develop and test a measurement sleeve for measuring dogs’ functional bite force, and to report locomotion-related values during a modified long attack. The measurement sleeve was found to be reliable, although individual tooth force could not be reported, as the forces were above the scale of our sensors. The dogs’ jaws pressing force, on the other hand, was not high, whereas during acceleration and deceleration the dogs were subjected to relatively high gravitational force equivalents. There are differences between two breeds of police dogs’ locomotion during the modified long attack task. The results gained from this study provide information which can be used to benefit the working dogs’ welfare during their use and training, as more in-depth understanding of the strains to their neuromusculoskeletal system is available. ABSTRACT: Information on the biomechanics of police dogs’ tasks is important in understanding their work-related injuries and dysfunctions. This study aimed to develop and test a measurement tool for dogs’ functional bite force and to report modified long attack-related kinetic and kinematic values. Twenty Finnish male police dogs, 7 German Shepherd Dogs (GSDs) and 13 Belgian Shepherd Dogs, Malinois (BSDMs), were included. Dogs accelerated 25 m and bit the helper’s sleeve, fitted with three force sensors. Dogs were wearing a 3D accelerometer and were videotaped with a high-speed camera. The sleeve’s reliability for measuring the dog’s bite force was evaluated via intraclass correlation and Cronbach’s alpha. Otherwise, a Mann–Whitney U-test was used, with significance set at p = 0.05. The sleeve’s test-retest reliability was moderate to good (intraclass correlation of 0.75), and internal consistency was high (Cronbach’s alpha 0.75). The GSDs’ median bite force was 360.4 N (interquartile range (IQR) 628.6 N) and BSDMs’ 247.0 N (IQR 289.8 N). Median acceleration maximum was 7.1 gravitational force equivalent (g) and median deceleration maximum was 11.6 g, with highest recorded forces being 9.2 g and 13.1 g, respectively. The measurement sleeve was a reliable tool for measuring functional bite force in GSDs and BSDMs. Forces related to bite, approach and impact in the two breeds were reported.