I just wanted to say how sorry I am for you. I know what it's like to loose a beloved dog. You joined the month Sassy died so I'm not sure if you know my story but anyways Sas was 10 years old, she was pretty old considered a senior. We had tried everything for her arthritis but it just took its toll on her. She couldn't even get up anymore and she limped with every step that she MANAGED to take.
Anyway, I really don't know about the circulation thing and I hate to say it but it might be her time. I hope to god that your vet can give you some options on what to do with Cassie. Only you will know when it's time in the long run..
((hugs))
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