While they were all answered elsewhere as you indicated, I'll comment here.
First, you cannot get/transmit HIV from/to a dog, HIV is HUMAN specific acquired immune deficiency- emphasis on "human" which should be more than enough clue.
A personal also cannot get pregnant from another animal.
Participation with vestiality, or zoophilia is a lot more common than people think, even larger numbers may not actively participate themselves but instead- consume the porn depicting it.
In my opinion the commercial porn is the abusive part as the animals are disposable and disposed of after filming.
As long as the dog is large enough and no force is involved, and the animal is not injured, there is nothing inherently bad about sexual contact other than what the crazy religious dogma says about sex in general.
As far as internet percentages etc goes, it doesn't matter what people come up with for percentages they imagine sound right, I have never caught anything from a dog in the fourty plus years I've had close contact with dogs every day. If they are vaccinated and dewormed and in good health there is little to be concerned about and dogs do not get/transmit any of the thirty of so human STD's.
Meanwhile humans can easily transmit fatal diseases just touching the same doorknob or elevator button- influenza kills thirty thousand a year for example and that's just from casual touching or breathing the same room air.
Please anyone who reads this don't answere.
I posted this same series of questions in another forum and they were all answered.
If you still feel the need to give me support, don't answere #4, for I have already been given the answere to that question..
Thanks.
-The_Mad_Hatter