My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today. I am sorry no one answered you earlier. Different experts sign in at different times.
At her age a few different things are possible. 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:
A stroke is also a possibility which you can read about here:
If for some reason it doesn't come up that way, it should on this page:
Organ failure can also lead to incoordination as well and at 15 sudden organ failure is a possibility. I would have her seen and have bloodwork done. If the vet does not mention vestibular disease, you should bring it up as fets sometimes miss that diagnoses.
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