The Jockey Club can use a lip tattoo to identify and provide information on a Thoroughbred horse--at a price.
     You can get the information by calling The Jockey Club Information Systems (EquineLine) at (800) 333-1778. They can identify the horse from his tattoo (if he is, in fact, a Thoroughbred). It'll cost you $35, and for that you'll get his registered name, the state in which he was foaled, the name of his breeder, a five-generation pedigree, and his race record (in abbreviated form). Click here to order on-line.
     That's the basic package. For another $15 you can get information on his female family, a complete report on each lifetime racing start, and his public auction sale history. 
     If you already know the horse's name, you can just order the products that tell you what you want to know without paying for the tattoo identification. You'd probably be more comfortable calling the number above and talking with someone who can help you order the right thing, but if you want to try it alone, click here.
     And they take credit cards.

     If you just want to know the year of birth based on the tattoo, here are the letters and the foaling years that they designate: