Well it depends if she likes it
Nasty.
Yes.
by licking my butt
Because it feels good and probally taste nice
no.
mask on ok
No
licking butt
Its called a Rim Job, a rim job is licking thee butt hole.
Your dog is not going to get sick from licking a cat's butt. Animals are always licking their butts.
Licking the butt before administering a pill is not necessary and is generally not recommended. Proper methods for giving a pill to pets or administering medication should be followed to ensure safety and effectiveness. If you have specific questions about medication administration, it's best to consult a veterinarian for guidance.
This is normal, this is how they clean themselves. If, he is constantly linking there could be a problem, take your dog to the vet.