You poor thing, this is so terribly difficult, and I can see your dilemma, and your struggle.
So long as there's life, there's hope -you are thinking. She still shows flickers of her normal doggy self, so it's hard to say "That's it, we're done."
I don't know about this specific problem she has. But it sounds as if it is always going to be -to a greater or lesser degree "managed" and never cured of course. It's hard to give up.
As I know little or nothing about this condition, you could ask for some advice from the vets, if you wish, on the Ask a Vet expert forum. Here is the link:
http://www.medhelp.org/forums/Animal-Health---General/show/112
Your decision is an extremely tough one, but only you can judge what to do. Does she eat and drink well, and seem to have some activity level, even slight? She is so young, you hate to give up, but again, you are the one that sees her actions and can judge things, even better than the vet. If you ever do decide that its time, you should find peace in knowing that you have done everything possible to help her, and she is a very lucky dog to have such a concerned and loving owner. You will still feel guilty, but deep down you will know you did everything you could, and it will help.
We can't "put them to sleep" when they are still getting something worthwhile out of life. With a chronic, or incurable sickness, that always means they will suffer -some. Even the fittest, healthiest -dogs (and people) suffer some....in life.
It's if or when they get to the point where there is no hope, and the condition, symptoms, suffering, no longer respond to medication, -even palliative -that we have got to be very very brave, let our love lead us. We have got to make that decision to let our loved one go free, away from that suffering.
There is always guilt. Even when it's clear there is no future (it was in my case when my dog had incurable cancer, could no longer pee suddenly, and after having tried every single thing to help him, no meds worked any more, and it was obvious there was no other way out. Because, even though in pain that night, he still wagged his tail -still barked and greeted the vet who came to the house to put him to sleep --those little signs of his normal self made me feel some guilt "Have I done the right thing?")
Looked at rationally and with compassion too -it was clear I had done the right thing. But I found it hard to switch from someone who for all those years had done everything to help and protect him -to someone who was now having him killed!
In fact, that decision to have him borne from this world and its suffering, to whatever is that Great Mystery beyond....was my final act of protectiveness towards him.
In my heart I knew that.
Anyway, it might be worth keep going, while there is any positive response to medication or treatment, and the benefits are not outweighed by the side effects. And like lindapalm said....if your dog is still eating, doing business etc, ok, still having some worthwhile life (sleeping a lot is ok, so long as there is decent life of some kind in between) and suffering is not the biggest thing in her life......
I am so very sorry for your situation but your so great for doing all these things for your girl.
I have seen the passing of two dogs in the family and will eventually have to say goodbye to my puppy, that I've had since she was 10 years old but hopefully not for another few years. One thing I think about when that moment eventually will come, is that I love her and nothing, not time nor distance can ever seperate a love like ours. I'll listen to my heart.
Trust me, you will know when it is time because she will tell you. When she no longer seems to want to fight and she has no passion for life, then it's time. Even though it'll be so hard for you, it's not fair to make her suffer just to keep her here with you. At the moment she doesn't sound like she's suffering and as long as you feel their is still hope, then I would try.
You can never be a murderer, you love her and she knows it regardless. Just don't forget all the fun moments or adventures you two had together. Also think about when she goes to doggie heaven which I believe there is, she'll be doing what she loves without discomfort or pain. Don't ever feel like it's not okay to cry either but don't linger in the goodbye because you'll see her again.
You will know when it's time, just keep your eyes open and listen with your heart. She will tell you. I've seen it twice, you'll know the sign/signs.
If you ever need someone to talk to, don't feel afraid to message me.
Little update:
Qiji is still with us and still going back and forth.
We have a better handle on monitoring (and medicating) her pain. Just filled a new script not too long ago which would last one month at peak dosing. We are going to re-examine where she is when the next re-fill is needed.
I know money shouldn't come into it, but since we are not treating the disease, only the symptoms, it makes sense for $8.00/month to let her continue as long as she can vs $250 to 'put her down' & cremate her. DEFINITELY won't let her suffer if the pain meds stop working, but it's worth a go at this point.
Enjoy every minute you have with her, hopefully there will be many more.