[Ellie May]

Older Yorkies can be diagnosed with liver shunt, so that isn't impossible.
MVD (microvascular dysplasia) is small shunting throughout the liver that that is inoperable. It can produce these symptoms.

The treat thing is hard because there are a lot of foods that she shouldn't have at all. Red meat is high in ammonium which can cause the symptoms you are seeing. Organ meat is also not a good thing. Really watermelon, apple and green beans are safer than dog treats but if you do give the dry L/D (I personally wouldn't want to...I'd get the Royal Canin kibble), you can use the Royal Canin for treats. It is very palatable.

You can do a Protein C test (blood test sent to Cornell), to try and rule out a large shunt. If all your vet is doing is giving lactulose and changin the diet, you may need to find someone else because that really is not enough.

You can homecook for her with the help of a veterinary nutritionist.

You may get away with boiling or baking some sweet potato for her (tiny pieces).

Something like Hepatosupport has milk thistle and some vitamins in it which would be a big help. If you don't want to give that you can give milk thistle for humans with vitamins b and e.