Guide dogs working in harness research
Pressure distribution under three different types of harnesses used for guide dogs
Aims of the study:
- Record force and pressure between the harness and the dog’s body on three different harnesses while performing various guiding exercises (straight, left turn, right turn)
- Determine whether there are differences between three harnesses
- Determine if different exercises affect measured force and pressure
H1 (a) is a traditional American style with a martingale strap (between front legs)
- Handle is attached to the chest strap in a few inches forward of the girth line with a quick-link on a metal D-ring
- Movement of the handle is restricted by loops, only girth strap is adjustable
H2 (b) minimal European harness
- Handle attaches slightly ahead of the girth line, in line with the chest strap
- Chest straps, top of harness, and girth strap are adjustable with Velcro fasteners
- Handle has a ball joint connection that pivots up and down
H3 (c) Norwegian style
- Handle connects with a plastic clip that is riveted to the harness with a leather tab and does not pivot
- Attachment at the girth line, above the chest strap
- Harness is padded in the area covering the spine, chest strap and girth strap are adjustable
Summary:
- Yes, there are differences in pressure/force between the harnesses.
- “The different harnesses had a significant influence on the force and the pressure values, whereas the influence of the exercises was not significant”
- In all harnesses, the highest load was found under the right side of the sternum. There is nearly constant load under the sternum due to how the harnesses are used. However, there was almost no load on the dogs’ backs.
- Highest pressure points recorded were in the American style harness on the dog’s right shoulder under the right side of chest. This is the most asymmetrical load of the 3 styles. The metal-on-metal connection and location of the handle attachment may be the reason.
Conclusion:
“This work highlights the importance of the correct selection and adaption of the harness to the dog and to the blind handler. There are differences among harnesses which are likely to affect the interaction between dog and its handler. A suitable harness will reduce load on the guide dogs.”
- “Anatomical studies will be necessary to show if those asymmetrical forces (torques) will have an effect on the musculoskeletal systems similar to the effects of asymmetric muscles.”
- “Reducing the load the harness exerts on the dogs by as much as possible is potentially important.”
Things to consider:
- Only the vertical components of the force to the sensors could be measured; therefore, we cannot make any conclusion in respect to the sheer forces
- Where and how the handle attaches to the harness may affect the load, this was not investigated
The shape of the handle may also affect the pressure distribution, but it was not discussed in this study - We do not know if these harnesses were fit properly to either the dog or person
Kinematic analysis of the influence of three different guide dog harnesses on the movement of the spine
The aim of this study was to describe the influence of guide dog harnesses on the spine movements of dogs guiding a blind person. The hypothesis was that a harness causes significant restriction of back movement.
Additional evaluation of the pressure distribution study:
Results
- Harness number one (H1) restricted the latero-lateral motion of the spine, causing a significantly restricted lateral and range of motion compared to when the animals worked without a harness during straight walk and left and right turns.
- Comparing walking in a straight line with turning right we found that both H1 and H3 caused significant changes in the dorso- ventral movement of the spine.
(Please note: Harness 2 and 3 are inconsistently confused in this write up.)
Key Finding
The American style harness “caused a significant reduction in spinal motion in the latero-lateral direction during all three exercises, while the other two harness types did not demonstrate this limitation.”
Conclusion
The hypothesis was confirmed by the data. It was proven that harnesses had an influence on the kinematic movement of guide dogs. The findings can be used for the optimization of harnesses.
Influence of Two Types of Guide Harnesses on Ground Reaction Forces and Step Length of Guide Dogs for the Blind
Compared the vertical ground reaction forces in a guide dog’s own working harness, and in a Y-harness
Each dog was tested with:
- A collar and leash (baseline)
- Their own guide harness with a leash, straight handle, and bent handle
- The Y-harness with a leash, straight handle, and bent handle
Conclusions
- When used with a leash, neither harness an effect on measured criteria
- When used with a handle under light pull, both harnesses showed clear
effects on impulse - A reduction in shoulder extension and the shortening of the stride length
- in all four legs was only seen when wearing a Y-harness with a handle
- Y-harness has a greater effect on the dog’s biomechanics during lead work than a Norwegian harness.
- The limited stride length could be a result of the location of the handle attachment
Limitations
- Dogs were tested in their own harness; not all harnesses were the same; presumably these harnesses were well fit and suited to the individual dogs
- The Y-harness was not a guide harness and not designed to have a handle attached
Discussion
- The goal should be the development of harnesses adapted to the individual dog in order to subject these animals to as little stress as possible during their daily work.
- This knowledge should be used to work on making harnesses that affect the dogs as little as possible. To date, however, there are no longitudinal studies that have investigated whether these biomechanical changes have an impact on the health of the animals.
- Further Research is Needed
It should be considered that additional physical disabilities of the handler could be further influencing factors.
Conformation of the dogs may contribute to the biomechanical effects (for example, the length of the legs, the width of the chest and similar factors).
Future studies should focus on the type of attachment of the harness, as well as the angle of attachment, which is altered by the size of the handler.
Attachment style and location
H1 American Style
Metal on metal connection Over the shoulder joint Most restrictive in all tests
H2 European Style Ball joint attachment
Behind shoulder joint, just in front of girth line
H3 Norwegian Style Leather tab attachment
Higher position, over shoulder blade
Dog Harness Research Takeaways
- Research is complicated and has innate limitations
- All studies indicate further research is needed
- Consider results carefully; avoid speculation beyond the results of the study
- Conclusions raise more questions
- Minimizing pressure loads and reducing restriction of movement should lead to better animal welfare
Content in this article has been taken from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9495002/
Influence of Two Types of Guide Harnesses on Ground Reaction Forces and Step Length of Guide Dogs for the Blind