That depends, STDs can be spread through anal sex if the people involved are not STD clean, there could be damage done to the receiver if not done properly, condoms are recommended to prevent the man from getting a bacterial infection, if it's a woman receiving anal sex, nothing (fingers, toys, penis) should go from anus to vagina without being washed first to prevent vaginal infections.
That depends, STDs can be spread through anal sex if the people involved are not STD clean, there could be damage done to the receiver if not done properly, condoms are recommended to prevent the man from getting a bacterial infection, if it's a woman receiving anal sex, nothing (fingers, toys, penis) should go from anus to vagina without being washed first to prevent vaginal infections.