I would not recommend any company serious about selling in the veterinary market use an anonymous forum to solicit information used in product creation or marketing. I now wonder about taking anything Vetigel says terribly seriously, if the company thinks reliable professional market information can be found from anonymous posters on a website focused on STUDENTS. And, seriously, do you expect an answer to the question to be anything other than "anywhere between 0 and 100"??? And, as it's been pointed out, they all cause bleeding to some extent; just cutting the skin causes some bleeding.
(edited for grammar)