Barking for their supper

I have two Bichon Frise's, Chloe aged 14 years and Flo, rescued from a puppy farm, is 'very old'. Chloe has recently been diagnosed with Cushing's disease and is on medication. Part of this disease is that she is always hungry. Before Cushings she was a very laidback girl especially at meal times.
She has now started barking while I am preparing her meal and Flo joins in. I have tried many ways of stopping this - to no avail.
Firstly, is this a usual change in behaviour with Cushing's? Have you any information on this disease?
Secondly, do you know how I can stop my dogs barking while preparing their meals?
Terri Sherlock, by email

Cushing's syndrome is a collection of clinical signs resulting from excessive levels of cortisol within the body. The most common signs are a ravenous appetite, excessive thirst, marked increase in the frequency of passing urine, pot-bellied appearance, and loss of fur from the flanks.
The change in appetite can be really marked. I will never forget the Irish setter which came to me initially because of his bloated abdomen. I subsequently diagnosed him with Cushing's syndrome and we started on treatment. Once he was stable, the owners then realised just how ravenous he had been - they noticed that he was no longer stealing food from their children's hands!
There are two possible explanations for why Chloe is barking when you are preparing her food. Assuming the Cushing's syndrome is well controlled, it may have become a behavioural habit, started when she was so hungry that meal times were the highlight of the day for her. The alternative is that she is still hungry because the Cushing's syndrome is not fully under control, or there may be another underlying reason for hunger such as diabetes mellitus. If you feel that she might still be hungry, then further investigation may be recommended by your vet.
If it is a habit, it will be difficult to break. Could you put the dogs in the garden or another part of the house before you start preparing their food, or will they simply bark at the door?
For further information on Cushing's syndrome, I would suggest look at the website http://www.Canine-cushings.co.uk.
Alison Logan, vet