Determining a dog's age.

How do veteranarians decide on the age of a dog?
I know about the wear and tartar build up on teeth and the fur, but they seem to come up with almost exact ages for the shelter dogs. (Ex: 1 year and 3 months)
Do they use teeth and fur coloring alone or are there more ways that help a guess at an age?
...and which conditions in the teeth come with what age?

They open it up and count the rings

I think they look at the wear on the teeth and there are markings on the teeth that don't disappear until they are a certain age.

I think they just use the teeth in all honesty , theres certain teeth that give indications of age.

Bev x

Lol not very well, my vet estimated muffin was 5 years old (this is before we got her chip details through) She was something like 11 years old at the time lol

I think it is mainly teeth, although could look for cataracts, joint movement I suppose. I will ask next time im on work experience

All I know is my vet said because Boyo had worn down his teeth completely gnawing on the metal chain he was attached to when rescued he can not tell how old he is at all.