"Hedgehogs are not pets."
Translation:Pindsvin er ikke kæledyr.
I think it's mostly the difference between pet (kæledyr) and domesticated animal (husdyr). Et kæledyr generally refers to an animal one keeps in their home and loosely means "Cuddle Animal", whereas et husdyr is more like an animal that's been bred for generations for humans needs, generally for work and food. (According to the Danish Wikipedia)
Which makes a lot more sense in this context - hedgehogs are not cuddle animals. It was confusing before because it seemed that house animal (husdyr) would mean house pet.