I believe I read in Miniature Horse World's article about DNA that the lab could run a sample like that. You would have to call the office to see how they would like you to fill out the DNA request form. Good luck.
More or less... I was going to hardship a mare that I never got the papers on so I called AMHA. Since she was registered in the current owner's name, I wouldn't be able to hardship her because her DNA is on file. I also couldn't find or get an answer from her previous owner so I was up crap creek without a paddle. I ended up selling her as 'grade.'