How far and how fast can I run with my dog (malinois cross)?

Two concerns with running with a dog - (1) joint health, ask the vet particularly about symptoms of hip or elbow dysplasia as running can ruin iffy joints (but not fully developed sound ones) and (2) wear on the pads, they will build up callous over time.

To that end, I would run whenever possible on shock-absorbing, non-abrasive surfaces like packed earth or grass (a trail through the woods or a bark-chip path through a part is lovely) and watch how much running you do on asphalt or concrete until you have more confidence in the dog's joint health and can start to see a harder pad callous developing.

My Malinois (my avatar) and I currently log 5-10 miles of him running next to my bike each week, plus at least two couple-mile runs and often a hike. He could do 5-10x that if I had the time! Just work up slowly and be sure to check feet after each run and take extra caution when the weather warms up again!

Improve Your Running Technique Now!

As the first answerer said, the dog has much more speed then you, and almost constant stamina so I guess you can run for as long as you'd like and as fast as you'd like, your dog is always going to want to run more.

Dogs are built for long distances running and stamina. Wolfs in the wild, which are direct ancestors of the dog can run after prey at full trot or run for hours, even days, until they literally run the prey into exhaustion.

A Border Collie working as a sheepdog clocked up 70 miles in one day at peak fitness, so your dog will do whatever you do!. Theres a sport called Canicross, they have some info online and I'm sure you'd both enjoy it.

http://www.cani-cross.co.uk/

The dog can run further and faster than you so whatever you'd like.

Just keep running Forrest!