A multi-scale analysis of modularity and ontogenetic changes in morphology and locomotor biomechanics in the domestic dog

This project has two over-arching goals: (1) to analyse how anatomy and movement of the skeleton change during growth in different canine breeds and how these growth trajectories might be linked with the development of musculoskeletal problems; and (2) to use this new understanding to inform health issues in dogs related to breed standards and aid development of new welfare technologies.

The domestic dog varies remarkably in body shape, perhaps more than any four-legged species. As such, the dog represents a unique model animal for investigating the limits of variation within a single species and how variations in shape interact with everyday functions, such as movement. However, unlike most animals whose forms evolved through natural selection over millions of years, the diversity in body shape seen in domestic dogs has been strongly and directly influenced by humans. Since Victorian times, dogs have been the subject of increasingly intense selective breeding with the goal of altering their functional anatomy for specific purposes, such as working tasks, agility or simply 'desirable' visual qualities.

There are major scientific and societal concerns about the welfare implications surrounding the breed standards (body shape) of certain dogs. The clear breed-specific prevalence for certain disorders strongly suggests that many of the physical traits favoured by our selective breeding may have a harmful effect on musculoskeletal function by creating an inherent predisposition to disease or injury. Unfortunately, the scientific data needed to understand the relationships between different breed morphologies and functional mechanics, such as locomotor movement, is currently lacking. This poor understanding has severely limited the ability of scientists, veterinarians and those responsible for canine welfare policy world-wide to address the health issues surrounding breed standards. Determining the morphological and functional variation in canine breeds, and how this variation may predispose certain breeds to musculoskeletal problems would provide multiple long-term welfare benefits. These benefits include an objective scientific basis for modifying breeding standards and policy, and improvements to the design of veterinary treatments, such as physiotherapy, orthopaedic implants and early diagnosis tools.

In this project, we will integrate data on anatomy and movement to address a series of hypotheses designed to test if and how breed standards place disparate, and sometimes negative, mechanical demands on the musculoskeletal system of dogs. We will compare how the morphology of different canine breeds change as they grow from juveniles to adults. Comparisons will be made at a range of scales from whole-animal measures of body proportions down to the shapes of limb bones and their joint surfaces, which must bear the loads generated in locomotion. We will compare how the movement patterns of canine breeds change as they grow, using a range of gait analysis approaches, including biplanar x-ray videography, which will allow us to measure fine-scale 3D motion of leg bones with unparalleled accuracy. Anatomical and movement data will then feed into biomechanical computer models that provide information on muscle and joint forces to test if mechanically unfavourable conditions exist in breeds that show a high prevalence for musculoskeletal health issues. We will deliver direct welfare impact from this science through direct collaboration with three project partners. Active involvement of the UK Kennel Club in our project maximises its potential to influence future breeding policies and dissemination of science downstream into breed societies. Partnership with two industrial collaborators will see the development and validation of new canine welfare technologies, specifically a new orthopaedic implant and an automated artificial intelligence tool to detect early mobility issues in dogs based on owner mobile phone videos.

This project has two over-arching goals: (1) to analyse how anatomy and locomotion change during growth in different canine breeds and how these growth trajectories causatively link with the development of musculoskeletal health issues; and subsequently (2) to work with key policy and industry partners to use this new understanding to inform healthcare practice in dogs related to breed standards and welfare technologies. To achieve this, we will quantify and compare the morphology of canine breeds to each other across ontogeny. Comparisons will be made at a range of scales from whole-animal measures of body proportions to the shapes of limb bones and their joint surfaces, which must bear the loads generated in locomotion. We will compare ontogenetic trajectories in locomotion biomechanics in different canine breeds using a range of gait analysis approaches, including biplanar x-ray videography, which will allow us to measure fine-scale 3D motion of limb joints with unparalleled accuracy. The morphological and locomotion data will then feed into biomechanical computer models that provide information on the muscle and joint forces incurred to test if mechanically unfavourable conditions develop in breeds that show a high prevalence for musculoskeletal health issues. Multi-body dynamics models will provide estimates of intrinsic forces that will subsequently be used to load finite element models of the elbow. In this way, we will test a series of hypotheses about the relationship between ontogenetic changes in breed morphology, motion and musculoskeletal disease/injury prevalence, leading to an objective scientific basis for modifications to breeding standards and policy. Finally, we will partner with industrial collaborators to apply these approaches to the validation of novel welfare technologies: new orthopaedic elbow implants (which currently show high failure rates) and an automated artificial intelligence tool to detect early mobility issues.