Few Thoroughbreds (if any) are totally American made. And that’s reflected in most five-generation pedigrees, which can be accessed for free from several national databases, including equineline.com and Bloodstock Research Information Services. How can you find foreign horses in a pedigree? Look for the symbols and notations on the page.

What in the world do those asterisks and equal signs and parentheses mean? History and added information?–?all courtesy of The Jockey Club.
As time marches on, the * in front of a horse’s name is moving further off the page, but it still often appears. It indicates that the horse was imported to North America. Foreign-born horses shipped to the U.S. or Canada prior to the mid-1970s have the * to denote a foreign birth. Examples, to name but a few, are *Ribot, *Gallant Man, *Alibhai, *Mixed Marriage, *Lady Angela and *Mahmoud.
In 1975, things became more precise with the addition of country abbreviations placed behind the horse’s name in parentheses. This code notes the country of birth of the imported horse and eliminates the need for the *.
Then came another symbol to clarify origin. Just because a foreign-bred horse comes to this country doesn’t mean the entire family follows suit. So add the = sign. Sometimes appearing randomly in Jockey Club records (thus rarely used in pedigrees which appear in Mid-Atlantic Thoroughbred), the symbol may be seen in front of the name of a horse never imported to the U.S. or Canada.
And on occasion, the horse’s name may include the = plus a country code after the name – again, to designate the foaling country while also pointing out that the horse never stepped foot in this country. To add another example, *Ribot’s sire appears as =Tenerani (ITY) and his dam as =Romanella (ITY). They never came to America.
If U.S. horses travel to foreign countries, they have the (USA) code placed after their names – so Americans in Paris (or Dubai, or Epsom, or Rome, etc.) are thus duly noted. Just trying to keep the worldwide Thoroughbred population straight.