Hai

We've got to extreme measures to work out our cat's sudden baldness. The vet has tried drugs, which had a short term improvement. Change of diet to Hydrolised food. No effect, but he's enjoying the food. And currently we're on Feliway to de-stress him. 

Well, I think we've found the change to his environment. We only really found out about this "visitor" when S accidentally set the old flap to No Exit one day and forgot to change it back. 

We came back to a smashed flap.
We've gone full change from a simple open/ close flap to one that now reads the cat's chip. 

Although this is proving a wee bit of a challenge on some occasions at the flap, largely it is working. We're working on the happiness factor of the cat and there are no more  "visitors", till that is it smashes this flap door.