What type of lawyer should I get to write a letter demanding the return of my property or else I will sue them in civil court?

Any California lawyer can write  a simple letter like the one you propose, provided you are willin to pay the attorney for his/her services.  Given that this is s small claims case, and you're not sure the thieves will comply, I'm not sure it's worth it.  You can sue in small claims court, but many small claims courts can only award money damages; you would have to sue in a court of general jurisdiciton to get an order compelling the thieves to return your dog (('m not sure if this is true in California).  If they didn't appear in court, yo9u would almost certainly win by default.  Thereafter, if they were ordered by the court to return the dog and didn't, the court could hold htem in contempt of court, and they could face many penalties, up to and including jail.  Needless to say, this is not as simple as it sounds and you will have to expend a lot of time pursuing this matter before you could ever get them incarcerated for contempt in a case like this, particularly as it would probably be very difficult to locate people who are vagrants.. If the dog is no longer in their possession, the only relief you could obtain from them would be a money judgment.  You would hae to sue the person who now has the dog to get it back, and you might not win, depending onwhehter that person bought the dog having no reason to believe that it was stolen.