I'm sure the family is coming at this with more information than we have. The fact that they have put up flyers in the area that he disappeared in makes me think that the last contact with him was in that area.
His last contact was on April 1st which was a Monday morning, who was it with and what did he say? Was it with a family member or was it to his job saying he wasn't coming in?
There just isn't enough urgency on the part of LE for me to think that there is consideration of criminal activity.
If he left voluntarily, why would he leave on foot, leaving his vehicle, that makes no sense at all.
The service dog description was on the Oconto County sheriff department web site.