That's really good news! Thank you for the advise. Will post with results!
There are several things that can mimic DM, and the thing that makes me think that it might not BE DM is that DM usually comes along gradually and not overnight, as you have described.
Before a positive DM diagnosis can be made it is advisable to test for thyroid function. Magnetic resonance imaging (MRI) and computed tomography (CT scan) are necessary to rule out other spinal issues that have similar symptoms but are unrelated to DM, but until you are convinced that her thyroid function is normal, I wouldn't spend the money at a canine neurologist when it may turn out that a daily or twice daily dose of Soloxine can fix the whole thing.
Hypothyroidism can be responsible for all of the symptoms that your Whippet has presented with, including the drooping eye. Neurological symptoms are part and parcel of hypothyroidism, so before you spend a lot of money at a canine neurologist, definitely do a thyroid panel to rule that out. Also, you said that it has slowly progressed over the last 6 months which fits with it being thyroid related.
Please post back and let us know how your girl is doing.
Ghilly
I meant Degenerative Mylepoathy.
Do you mean Dermatomyocitis? As far as I know, that only can be determined for sure by a skin biopsy. Was that done? It can affect Collies and Shelties. There are definitely other diseases this could be.