2.5 Year Old Aussie Problems with legs and urine

I'm waiting on a call back from the vet and wanted to get some insight while waiting. I have a 2.5 year old female Aussie. Today she has been having issues with her back legs. I've had to help her up the stairs because she kept slipping and it was like her back legs wouldn't work. She had pee dribbling as well all the way up the steps. Her legs and behind have been wet today, which I first assumed was from sitting outside in the snow when she was outside, but I now believe it to be pee because she hasn't dried and is leaving piddle spots where she lays, even on her bed. When she's sitting she's keeping her legs out to the side. She seems to struggle with standing from laying down. She is limping a little off and on. When she is seeming to walk mostly normal without limping, her legs seem stiff. My first thought was UTI but could that cause the issues with her legs or could this potentially be signs of something else? I appreciate taking the time to read this and any input given.    

Hello!   There are a number of things that could be happening here and I'm pleased that you have that vet calling back.  One possibility for example, is that the nerves supplying the bladder and hind-limbs have been damaged or disrupted somehow - for example, the spinal nerves.  A neurological examination would help to reveal such a thing.  Other possibilities may include muscle damage, bladder pain / infection or severe arthritis.   Please will you know what your vet decides?