There are dogs living at the top of Doi Pha Hom Pok national park.  Presumably to keep the lone ranger there company.

 

There are dogs living in Khao Sok national park at one of the ranger stations there as well.

 

They're the two examples that I can recall but there are probably more I forgot about.

 

I think if you do see dogs there they will more than likely belong to the rangers there, and possibly you are more likely to see them at the remote ranger stations where rules are a bit more lax.

Yes - there dogs kept or allowed to stay by Rangers - I can give you several examples of dogs in National Parks up and down the country     this shouldn't happen - it is just another example of how unprofessional Thailand is when it comes to managing their National Parks and wildlife reserves.

        

Saw another dog at the top of Phu Kradeung last week.  I admired the effort on the dog's part, that's a hell of a walk to get there.

As long you pay the farang entrance fee for the dog you can take him with you