Catteries also won't accept cats without full vaccination certificates. Not too sure about the wisdom of not keeping up vaccinations on elderly cats. My 13yr old cat had been kept up to date with her vaccinations, but still contracted 'cat flu', and was desperately ill. She did however survive after being put on a drip and medication. The vet commented that had she not been up to date with the vaccination she would not have survived 24 hours. It appears that the vaccination against 'cat flu' is very good but not 100% perfect, but it does give the cat a fighting chance of survival with swift veterinary intervention.