There is a great body of work and reference already out there Gaits so I am not going to go through them on this blog. My advice would be study the material below and always keep in mind the spine when studying and applying quadruped mechanics. If you find anything more on gaits please forward to me and I’ll put it in the list.
The purpose of this web site is to enable you to recognize limb patterns of the
major gaits exhibited by cursorial quadrupeds (running animals).
http://vanat.cvm.umn.edu/gaits/index.html
Note: I love this site, bookmark it!
Dr. Stuart Sumida
http://www.stuartsumida.com/ANIMATION/LocomotionImages.pdf
(must read)
Five Minute Gaits
http://www.5MinuteHorseLessons.com/
This guy is a legend.
Animating Horse Walk Cycle –
Rrichard Wwilliams Animator’s Survival Kit
http://www.nature.com/articles/srep08169
A simple rule for quadrupedal gait generation determined by leg loading feedback: a modeling study
warning: this goes pretty deep
Other Gait Links
http://www.ccresteds.com/canineterminologyformovement.pdf
http://www.classicaldressage.co.uk/The-Horse-s-Gaits/the-horse-s-gaits.html
https://en.wikipedia.org/wiki/Gait
https://en.wikipedia.org/wiki/Horse_gait
http://www.timrudder.com/animationmentor/animating-a-quadruped/
Gif Reference (middle click to view)
Video Reference