
Depends how you want to do it. A decent webcam will work with Skype, and you can set it to answer automatically and you can mute it from your end so the dog's don't know anything's happened (this is how I watch mine for separation training), but it requires your PC to be on all the time.
The other usual option is an IP camera. Better quality usually, better field of vision (bear in mind that webcams are designed just to film your head and shoulders, so you don't get a lot of the room in shot for monitoring purposes), a lot are remote controllable so you can look round the room via your phone/tablet/netbook/laptop and some also have audio going both ways if you want it. But, they are harder to set up and need IP compatible software/websites to work (no-ip.biz is one). Personally I never got to grips with mine, hence my webcam setup but the view is restrictive - I'm currently looking at wide-angle webcams.
All that said though, I am with Daisy and I would concentrate on your holiday!