You can train with any blood. A good dog does not just track blood, but is able to differentiate on the specific wounded animal you are tracking - by all of that animal's individual scents, not just the blood. An experienced tracking dog that knows what he is doing will track the right animal through a herd of the same species by the individual scent of THAT specific animal.
Oskar and my wife at the end of a very difficult trail with the happy hunter. You can see where this deer is hit. We started tracking 15 hours after the hit in a 100 acre CRP field under EXTREMELY dry conditions. The hunters (4 guys) searched pretty hard before calling and couldn't find him. This was about an 800 yard track..The stripped hair on the ground behind the deer isn't from coyotes, its from Oskar attacking the carcass:
Here is a better picture of the dog.
He's our sweetie. Sleeps in the bed and gets his belly rubbed every morning first thing. DONT SPOIL YOUR TRACKING DOG!
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Here's my favorite - Oskar on his first woods walk in Indiana - 9 weeks old.
Ryan