LS,
our two cats are fighting heavily since 2 days, while having lived in
harmony for 4 years.

It started at the moment when they had to go to the vet for thair yearly
vaccination.
It is a female (ragdoll) of 4 years old and a male (european shorthair) of 7
years old.
The female attacks the male and he tries to hide as much as possible.
When a confrontation occurs he first makes a spitting noise at her, then she
follows him making very loud aggressive noises.
This behaviour does not seem to go away automatically.

Is there anyone who has experience with this?

Thank you, Marcel