My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. I can give you some informaiton.
As you know your dog is quite elderly so that speaks volumes to the care you have given her. It’s possible your dog is suffering from vestibular disease. Symptoms include standing with legs spread out, swaying, head tilt, abnormal eye movement, walking sideways, falling over and may include vomiting. There are a few things that can cause this condition such as an ear infection, some medications and old age. Have your Vet check your dog for this condition. Here are some great sites on this condition:
The good news is that if this is the problem and it is due to old age, the condition normally resolves itself over a few weeks. Your vet will most likely prescribe dramamine or bonine to help with the symptoms. You can read about dramamine and bonine usage, precautions and dosage here:
However, organ failure can also lead to disorientation and hindquarter weakness as well in an older dog.
I strongly suggest you have your dog seen by your vet as soon as possible. I would expect at a minimum bloodwork is going to be done.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.