Thanks in advance!
From memory the story is about a guy with a horrible disease (I think all the men in his family had it). He discovers a fang that belonged to his grandfather and ends up getting his blood on it. Out pops a dog god/demon who "eats" the disease and takes his body in exchange.

cheers

Could it be Konoyo Ibun?

Thats it!!! Thanks a bunch weird1 😀