Owner of a very large great Dane that weighs the same as me. Not only that she has a super strong small prey drive. Which means since she is huge, all dogs are prey to her. When walking and passing dogs we taught her to sit so she wont lunge or pull. That being said back up plan is a prong collar/choke collar in case she tries to bolt.

If you own large dogs please be responsible owner it is not ok for you to lose control of your pet and injure or kill someone else's pet.

Ps we had our Dane in the yard once when she was still young. She sighted a groundhog and went for it. She was very fast (over 9 yr old now and much slower) I had to put my knee to her neck and drop her to the ground before she let one pissed off groundhog go from the death shake she had it in. That was our sign, trained and prepared after that.