Hi E & J! Hmm, well even a short separation from one bunny going off to the vet & returning with odd smells about them can cause another bunny to reject the other. It can take up to a month for the hormones to dies down, so you have a ways yet. I think a combination of both things has caused some discourse amongst your rabbits. Have you tried slow introductions with them or did you just put them back together like normal was pre-surgery? If they are not house side-by-side you might want to try that at first and put enough space between so noses don’t get nipped. YOu can also switch cages back & forth so they get used to each others scent again. If it gets too bad, try the stunt-bunny double i.e. stuffed toy with the others’ scent on it too see if the other bun warms up to it. Try slow, supervised introductions and keep a towel handy for separation. You might even want to hold off until the hormones die down. Take a peek at our BONDING section too. I sure hope things settle down for you and your two get to be best buds once again.