I would like to share with you the reason behind them picking on the Female cat... Yes they have all been de sexed... I took her to the vets to see if there was a medical reason behind this! Maybe the cats know some thing we don't! As it turned out she had an infection in her bottom which would of caused the scent glands to change. This was the reason behind the agression.
Regards
Amanda
RESPONSE:
Thank you so much for the update! Yours is a prime example of why a visit to the vet is often warrented when there is a sudden change in cat behavior!
And a big thanks for opening your hearts and home to cats in need!