Use the e_loop:[number]
transformation for looping videos and animated GIFs: https://res.cloudinary.com/demo/video/upload/so_4,eo_8/e_loop:5/happy_dog.mp4
.
For GIFs, the number is optional; leaving the number value empty, will result in an infinite loop of joy:
![Loop GIF Happy Dog Loop GIF Happy Dog](https://res.cloudinary.com/demo/video/upload/w_400/so_5,eo_8/e_loop/happy_dog.gif)