Lady Liz...my thoughts are with you going into the crash course of learning that Liver disease entails I was in the same position as you this time last year.
I'm actually surprised your vet didn't put her on a corticosteriod like prednisone/prednisolone.
as it's the main drug of treatment of the baseline condition. Denmarin is a support medication that may help the liver to regenerate some function...and other meds are used if the disease progresses to alleviate specific symptoms...it's all about tweaking meds and diet around to try to replicate the liver's function as best we can and not put it under further stress.
The most important part of living with liver disease is diet and it can be quite challenging at times. It's great that your girl is tolerating the hepatic food well as this makes it a lot easier! I'm guessing you're using Hills L/d as you mentioned canned.
She might not need to be sedated for an ultrasound...my boy just used to lie there and enjoy the "belly rub" ...and he didn't need sedation for x-rays either!!
If the ultrasound indicates changes to the liver...you then have to weigh up if a biopsy is the way to go...it's not an easy decision as there are a lot of risks involved when a dog's liver is already compromised...but if she's well enough to handle it, it can provide some definative answers and should be done sooner rather than later (my boy was already too compromised to be able to have one and the risks of bleeding too great)
One of the things that stood out in all my research was the efficacy of including oatmeal in the diet. It helps to regulate the passage of nutrients through the GI tract as well as protect the neural pathways from damage due to protein digestion by-products.
I wrote about my experiences in these threads...they're long and rambling and not necessarily what you might experience...but I included some links to some of the research I did, and others offered excellent links and advice too. I'm happy to be part of your on-line 'support' team if you want it
http://www.dobermantalk.com/doberman-health/49530-zillahs-gone-back-downhill-rapidly.html
http://www.dobermantalk.com/doberman-health/50921-pounds-poops-zils-road-recovery.html
I'm really hoping and praying that you're not dealing with liver disease, but just a temporary inflammation that will clear up with treatment. I hope you continue to keep us updated on how all her tests go...fingers crossed they're showing improvement.
keep a positive attitude and go get that ultrasound done. (((hugs)))