Having her desexed seems like a rather radical solution. Phantom pregnancies are exceedingly common in all breeds of dog and this is usually not something to be alarmed about. Problems usually arise when the phantom pregnancy is in its advanced stages, because when this happens mil is produced and various problems can arise.

Usually phantom pregnancies ‘go away’ on their own accord and your dog will return to normal behavior. In my experience, allowing them to nest can exacerbate the problem, so try and prevent her from hiding behind armchairs etc. The advice your vet gave you is appropriate – make sure she has nothing which she could mistake for a ‘puppy’. I expect your dog to return to normal given a few weeks of patience, but if any other physical symptoms arise or it continues for longer than this, you should return to your vet.