I think they have a general sense of time. I wouldn't use them to clock Olympic swimming events but they certainly know day/night/best time to chew up furniture, stuff like that.

I'll ask my GSD for his opinion on this matter.

Perhaps you should ask, "Does time have any concept of dogs?"



In which case I would answer, "Broccoli".





And that is the meaning of life.

I've always thought the 5 minutes : 5 hours thing was that they weren't sure if you were coming back, and they are simply happy that you did.  For example, I can be outside of my dogs view for hours in my work shop, but they know I was there, and don't give me the welcome home dad dance that they do if I'd just run into town for milk.

I don't really know, but my Lab will let you know it is time for dinner at around 5pm (+/- 15 Min) everyday.

I was gone for about 9 days recently.  My beagles definitely acted differently when I returned than when I get home from work every day.

My dogs always seem to know when it is time to eat.

Supposedly no, they have no concept of time.  At the same time, they say dogs have the IQ of a 2-4 year old.  

Like others have mentioned, as a kid, my parents' dogs would get excited around the time Dad would get home from work, and would get worried and pace around if he was running late.

I don't know what my dog does, but yup, she goes spazzy whether I go to work, vacation, or just out to the garage to get a tool.  I can also say that she recognizes when we are getting close to the parents house, which is a 45 minute drive.  She'll be sound asleep in the back seat, and about 5 minutes out, still on the highway, she'll perk up, start wagging the tail, and looking out the window.  as we turn onto their street, she starts getting spazzy.  So, they must recognize a bit of time, or their SuperHearing and SuperSmell must really be kick ass to recognize things like being within a few miles of a particular place.

I don't think they recognize time so much as they pick up on patterns and they know that things happen in a certain order.  The dog knows you wake up after it hears the neighbors garage door open.  The dog knows it's time for dinner after you've come home from work and read the newspaper.