Cat wa****ng its fur off

Hello, all: I was chatting with a neighbour the other day.  I was asking 
why her cat, that I see in her kitchen window, has a cone type collar on. 

She said that her cat washes itself so much that its been taking the fur 
off.  Her vet thinks it might be a skin allergy and has suggested steroid 
treatment, but my neighbour wants to avoid drugs if possible.  So the cat 
is always wearing this cone to prevent itself from wa****ng.

While talking to her I wondered if she might be able to put something on 
the cat's fur--tal*** powder, for example--that wouldn't taste good and 
would discourage the cat from wa****ng.

I don't know.  Has anyone had this problem?  Any suggestions?  I feel
badly 
for the poor cat which, my neighbour tells me, is a very sweet natured 
animal.

Many thanks.

David in Toronto