Disclaimer: Wheaten Health Australia cannot provide recommendations for treatment or diet. This must be done by a qualified veterinarian.
If your wheaten is diagnosed with PLE or PLN (or both), your vet must consult with Dr Littman, the US specialist in PLE/PLN on tailoring a treatment. Bear in mind that not all the drugs recommended for PLE/PLN in the US may be available in Australia and that a special regimen may have to be put together for your wheaten. Some drugs available in the US may also be known by other names in Australia.
Wheatens with PLE/PLN will require a diet that helps them to retain protein. Wheatens with PLN, for example are recommended to have Hills Prescription Diet Ultra-ZD, which is available from a veterinary surgery. Ultra-ZD's protein source is hydrolised (turned into water) to help retain the protein in the bloodstream. The most important thing is to keep your wheaten eating. If a wheaten doesn't eat, he or she won't retain protein.
Some vets may recommend fluids to flush out the kidneys of toxins. Be aware that this might not work so please discuss the pros and cons of this action with your wheaten's vet. At least one Australian wheaten ceased eating after being put on fluids and was euthanised shortly afterwards.