There are many forms of Paganism and witchcraft, just because one group does something does not mean all groups do. Wicca is a very loving, peaceful, "harm none" religion. Wiccans do not cast spells or do things to harm others. There are many Wiccans who are vegetarian or even vegan to adhear to the Wiccan Rede of no harm. The most dangerous spell a Wiccan has been known to cast is a love spell over someone who isn't aware such a spell has been cast. Even that is a small percentage.
There are some types of witchcraft where blood and animal parts are used, but not in Wicca. Each path is different, so if you don't want to use blood, cast certain spells, or use certain items you don't have to. Do some soul searching, meditation, and read a few articles or books by reputable Pagan authors to gain further information and draw your own conclusions.