Do you have the papers from when you bought Yoshi? Did you make the police aware of the monetary value of the dog as well as your how much you love him? Maybe the police would be a little more interested if they knew the value of the dog. I wouldn't make that info public as it might make someone less honest want to keep him even more.
I can't help but wonder if you had a famous name or your dog was some big prize winner worth big bucks if you'd gotten more help from the PD.
__________________ Mammadoodle to my Yorkiedoodle Barney and our crazy cat Ms. Sassy Pants.  RIP Audrey-Belle 
Within the heart of every stray lies the singular desire to be loved |