Dogs can have their day!
Go mountain biking around Callahan State Park you won’t be disappointed. Dogs are allowed here. The park has many trails running through it. There's quite a variety of terrain, from challenging hills to bridges to level ground.
The trails are fairly wide, meant to be used by several people at once, so don't expect any single tracks. It’s a great place to hike and walk with your canine companions in MA. But, it is a multi-use park that has mountain bikers and horseback riders. The open field near the pond is a great gathering place for dogs to play with each other.