I wouldn't worry about it. If it isn't wilting just leave it alone. If it wilts cut it off at the break. The plant will likely push more stems from the base. Sometimes I partially break a stem when moving it about and it seems to heal itself if I push the stem back together.

Next spring prune as usual.

One of the many lovely things about clematis is that they come back from damage well. I think that since it isn't wilting it will be fine. As far as winter . . . my The President gets killed to the ground by cold pretty much every winter and comes back from the roots and blooms just fine, so I would have no concern about the dog's damage effecting winter hardiness.

Oh thank you both!
I've really loved having these vines and was so worried I'd have to completely start over with them. Thanks for the great news! :)

KHershey,

As others have said, Clematis are tough little plants. But please do keep an eye on the dog as Clematis are also toxic to dogs (and other animals). If you see: Salivation, vomiting, diarrhea - please take the dog to the vet immediately.

Good luck!

My dog chewed through mine half way up..... Is there anything I can do

The bottom half will grow fine next spring.