oK my two cats are litter mates. they've been together since birth. Jada had surgery so she had to stay over night at the vet. when my husband brought her back her sister Bella started hissing and doing that growling noise cats do. She has been doing this since Wednesday!! I dont understand why she is doing that to her. Every time Jada walks near Bella hisses. She even hissed at my husband. The thing is Bella was NEVER like this. Its a totally different cat!! What could be making her do this? Doesnt she know its Jada and smell her scent?? Need advice!!