Hello mate, I have a 12 week saluki x greyhound and since I've hade her most foods seem to go straight thro her with clear mucus and a little blood in her poo, she has been to the vet as she dropped a bit of weight, the vet assured me there was nothing to worry about I've put her on skinners puppy field and trial and she eats well has put weight on and her poo is nearly back to normal, hope your pup is ok let us no.
Cheers joe.