I have visited Dog Mountain a number of times when our dog was younger, including to a fundraiser for the local efforts to build a dog shelter. Our dog won something like the most enthusiastic tail wagger or similar - because of how cute our daughter was, showing her, I suspect. Stephen's stories and pictures are magical, and we brought our children to the library to hear him read his stories and meet some of his dogs, and were excited to see the full range of his work on display at the mountain. It was a great place to take our dog cross-country skiing when she was younger. I also paid a special visit to post a card when a dear neighbor's sweet dog passed away, to sit quietly in the sacred space and reflect on love.
If there is no special event, you could spend anywhere from 20 minutes to (perfunctorily) browse over books, see the chapel, and stretch your legs for a minute, to two or more hours, if you take your dog for a real walk or ski, sit to meditate, or spend more time looking at books and art.
The tragedies around the mountain, due to depression the owners had associated with financial troubles leading to needing to lay off staff, and then for Gwen, related to her loss of Stephen, are heartbreaking. The staff have been committed to trying to keep the Huneck's dream alive - a beautiful spot for dogs and those who love them, open without charge. I don't know how it can continue, but it would be marvelous if enough people stepped up to the plate and helped. This is a lovely sanctuary, and keeping it free helps people come whenever they are moved, without thinking about whether it will be a long enough visit to justify the expense, or too long a drive to go spend money when you aren't sure what you'll get from it.
It is also a great place to have a picnic, but it doesn't sell food - or at least, didn't the last i knew. So bring food and a blanket, if you wish to picnic.
There are reasons to visit the St Johnsbury area anyway, but even if you are just passing through, especially if you have kids+/- dogs in the car who need to stretch their legs, be sure to check the hours as they might be highly variable in this transition time, and stop by. Young children will be delighted by the fanciful chapel, where your dog can walk right in with you. And especially if you do not take your children to any house of worship, this is a low-key and welcoming, inclusive place to let them experience a sacred space built by humans. And if staff don't come up with a plan for sustainability, you may not have a chance to visit it later, so visit it now!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.