A lot of words are being said about Police Dogs (emoji)(emoji) were deployed without respirators while CS was used not just last night but during previous operation.
Dogs are not effected by CS due to the under development of their tear ducts. ( https://en.m.wikipedia.org/wiki/CS_gas# ) This is because a human body is far more developed than many other animals on the planet. It was tested and proven. Police dogs are very expensive, not easy to train up and any damages to their health will shorten their service life.
Hong Kong Police are not doing anything wrong with Police Dogs.