Poppy 13 yr old Border Terrier

[Bridget and Poppy]

Hi folks, I'm Bridget and I have a 13 yr old border terrier Poppy who has been diagnosed with Addisons. I am looking for advice please regarding her condition and ways to help her.
So Poppy suddenly stopped eating which prompted the trip to the vets. I was on the verge of taking her because she has been drinking and peeing excessively, been wobbly on her legs and has had confusion which I put down to being dementia. Symptoms had been there for a good few months gradually getting worse.
The only thing the vet found wrong was high blood pressure and after a nights stay on fluids she was sent home with tablets for high blood pressure. The vet also suspected a brain tumour because of the way she moves. 5 days later she stopped eating and was shaking violently.
The vet checked her blood glucose it was 2.6, she has never had any problem like this before.
I insisted they checked for Addisons. Her cortisol was 54 rising to 71 have the stimulation test.
She has had 2 steroid injections and has come home on prednisolone.
I'm struggling to get her to eat. She is drinking and peeing herself. After 4 days I went back to the vet, they ran bloods and her lytes were ok so she got sent home with appetite tablets, which have worked ok, but today I'm struggling to get her to eat.
The vet is 99% sure she has a brain tumour and says the Addisons is Atypical and she probably has a tumour on her adrenal gland. They said she is too old to develop Addisons.
Can I hear some views from you please. Does the treatment sound correct?
I'm very worried about Poppy. Thanks in advance x

[Catherine]

Did she have blood tests for her kidney and liver in case it is kidney disease? It could be more than one thing going on. Was Poppy's urine tested in case she has a urine infection as well?

Have you read this: http://cimda.co.uk/smf/index.php?topic=581.0  and 
http://cimda.co.uk/smf/index.php?topic=575.0  and  http://cimda.co.uk/smf/index.php?topic=909.0

Apart from the Preds. what other medication is she having?

You can use the search facility on the main page of this website and it will bring up lots of posts that might help. Addisons is more usual in younger dogs but it has been seen in dogs as old as 14.