What to do when your dog keeps running away with your neighbors dog? And if you guy said have seen a while and brown female boxer mix dog with a brown brendell mastiff mix male dog?

Yes often it's just a question of spaying or neutering.Also please chip your pet, this way you can get it home safely when found. I had a female little beagle,that was too young too be spayed , so while waiting for her to get to that age.She ran out the door and there was the neighbors little Romeo namedBo Jangles waiting outside , and they ran off into the sunset together needless to say I became the grand parent of 9 brand new puppies.. You can call the humane society to see if they can recommend a low cost neutering clinic. I don't know if they still do it but they use to have mobile units go to different areas of AZ and spay and neuter free. Altered Tails in Phoenix is very reasonable. Just Google low cost neutering , and you should get more info. Good Luck

Have you tried letting them have " play dates"? I train service dogs, getting dogs to stop running away is tough short of fencing or, electric monitoring under your grass/rocks unless they've been taught boundaries. They can learn but it takes daily work. Play dates may help with the fact the dog wants to be social with the other animal. And yes I have seen the mix, it'll be big but beautiful. I may take a puppy if you have them. A new breed of service dog. 😉BTW, spaying is always a good option and relatively cheap at the bigger shelters who offer vet care as well.