No you wouldn't have to declare, it's the dogs money afterall you are selling all of it's puppies. She would want it as a retirement fund to go on a holiday or something special.
Ps Your dog want's cash for the puppies and the money to be kept in a safe place, she doesn't trust financial Institutions.
This may depend on whether you are operating a business or a hobby and submit tax returns. There will be costs involved in breeding these animals so how were these costs funded?
You will have to declare this income Keith, as the sale of the pups will be deemed to be a windfall for which you are undoubtedly accountable for to your creditors.
If I were acting for you, I would want to understand the costs involved in breeding the pups, which ought to be deductible assuming you have been paying these whilst maintaining your IVA contributions. It is then up to your IP whether they claim the windfall or not.