My Mom first introduced me to it. She said that every time a cow got injured, they applied pine tar to the wound. Apparently it's an antiseptic, and keeps everything out while sucking out the bad stuff. (You see how deep my understanding goes, lol!) They ended up applying that information to horses as well. I've even seen it work on cats and dogs.
We had an old mare (I'd say mid-20's at LEAST) that, we think, got attacked by a cougar. (It looked similar to claw marks.) She was a slow mover, as she had bad arthritis. The gash on the side of her stomach was about a foot long, and a big flap of skin was draped over at the bottom, exposing a gaping wound. It was pretty nasty. My Mom just applied pine tar, stitched her up, and applied more pine tar to the outside. She healed very well, and got through it with no issues. Though I do admit that my mother's stitching skills weren't pretty, and the mare had a thumbs-width of skin that looked bunched up on her side.
She ended up living for about 5 more years before dying one winter.
Just curious if anyone else uses pine tar.
I've used it on abscesses and cuts, mostly.
On a side note, I did find "Pine Tar Soap" at an organic store! It smells like machine oil going on, but it definitely clears up any acne!