I like to keep ____ as a pet because ___________________________ 写单数还是复数?比如I like to keep dogs as a pet because it is ve

I like to keep ____ as a pet because ___________________________ 写单数还是复数?比如I like to keep dogs as a pet because it is very cute.
I like to keep dogs as a pet because they are very cute.哪个正确呢?
I like to keep dog as a pet because they are very cute.
那这样对么