About 3 weeks ago my small cat (6.7 pounds, not fixed) had to go the vet for an emergency with little eye. We got the sauve and came home. As soon as I let her out of the pet carrier she started attacking her former best friend. She will even seek out the large cat if the large cat is not on her pillow. Up until the time I took her to the vet they even slept on the same pillow on the bed. Now the large cat(17.9 pounds, fixed)has to defend herself even if she wants to go the litterbox. PLEASE help they are driving me crazy.