Heath-row airport doesn't allow dogs. We have 10 hours with a dog there. Any ideas of where and where to do?

We will be waiting for a flight after checking out of a hotel and will have approx 10 hours. The dog is coming with us and also needs to be checked in but,the problem is that it seems that the airport doesn't allow dogs in the terminals. If anyone has had a similar experience,perhaps they have some knowledge or experience to share Sorry about Heath-row the spell checker insisted on it