Kakashi must have returned from a mission and when he learnt about what happened decided to catch up...

Summoning his dogs could mean he used them to track em... and I seriously am hoping that his dogs are gonna find Chouji and Neji, and thus save them, before catching up to the rest.

Also... Shikamaru, Kiba, Lee and the sand siblings should catch up to Naruto way before Kakashi, so it makes sense I mean.