Deer Brook Trail begins on Route 73, 1.9 miles south of the High Peaks sign in Keene, 0,1 north of a steel bridge over the Ausable. It is an ATIS trail and passes through private land. The private land is not part of the AMR, so dogs may use this approach to Lower WJ. There is very limited parking along the highway at the trailhead. The lower part of the trail (most often used to access Snow Mt) has both high and low water routes, neither should give your dog any problems. As you approach the top of the Deer Brook Trail there is a connector trail to the W.A. White Trail for the climb to Lower WJ. I do remember the steep section near the top of Lower WJ that Zac mentioned. Most dogs should be able to handle this.