I brought one of my cats home from our vet yesterday
( she just had an exam ) and
when I let her out of the pet carrier my male started hissing and growling at her and hasn't stopped . This is the second day. He acts as if she is a new or different cat. What's up with that???
This is very common. Your male cat smells the other animals from the vets clinic. Try to wash of the cat with a wash cloth and some cat shampoo. This may help. vetcare