I just noticed that there is a swollen toe joint on my 2yr old golden retriever's rear paw. It does not seem to be slowing her down, and I can see no signs of a wound.

Should I be looking to get her to a vet ASAP or can I wait and see if the toe changes in size?

Hi, Meliisa,
This sounds like a 'knocked-up' toe if it is the toe joint itself, and not the web between the toes which is swollen.
I would wait and see what happens, if she is not lame on the paw, it is unlikely to be serioius.
Walter