It is possible my last dog had this. I assumed it was arthritis as she was about 13 when it got obvious. She was not able to control her back end as well but was not in any pain.

I got a wide band and would loop it around her middle to help her walk outside.

I also got her a dog wheelchair.

She was not so keen on that but with me helping her total movement. A vet even laughed when watching her pee as she just lifted both back legs and went I had the middle balanced and she took the weight on her front legs.

She lived on until she was 15 then as her sister had arthritis that we could not control the pain of and as she was now also deaf and blind I let them both go together. If her sister was out of the room she howled until someone came to get her she would not have been happy by herself.