Odd Aggression

Noomi does not like change. She has a rather strange way of showing this, growling, howling, and hissing loudly and aggressively - at Lily.  If pressed, she runs away, grumbling and growling all the while.  Lily, is pretty immune to these displays, as if she knows that they aren't properly aggressive.  I'm glad she does, it fools me.  

The latest incident was when I was about to go into hospital, and my sister had arrived in the house to look after me when I came out. Ann has her own cat.  Both cats were perfectly fine, until nearly bedtime when they managed to get into the guest bedroom.  Then Noomi lost her mind. A few minutes earlier the pair had been snuggled up together on my lap, now Noomi was a growling, hissing maniac. In the end I had to let her escape into the yard overnight (it's fenced, but I normally have them both in at night). 

This nonsense carried on for several days.  Lily being the more mature of the two, Noomi growling and grumbling whenever she caught sight of Lily.  Then, it was all over. Ann had returned home, and the two were best buddies again.  I can only assume this was redirected aggression.  The smell of Ann's cat had set her off, and Lily was the only target available. 

Update 2020

Just reading an article about a cat in the newspaper who had to go to the vet and her companion is now similarly upset. Apparently, it is quite common for them to refuse to believe eyes over smells.  Did not know this!