Speaking as a stage 5 , late stages advance rapidly. Your mobility limitations become mobility loss,...then a wheelchair, eventually confined to bed, where I find myself now. A trained Parkinson's service dog will be quite expensive, require a caregiver for the dog, In retrospect, bond with a companion dog as soon as possible. I must say this, Parkinson's eventually gets ugly. Enjoy the "now" with an unconditional love of a companion dog. "May the sun shine warmly upon your face, and until we meet again, may God hold you in the pam of his hand".

Be careful with one aspect - get a trained dog and one that meets your individual needs. A friend of mine obtained one which was not trained and with his first stagger he and dog collapsed.
His new dog is fantastic and both dogs get along together

I trust that my dog knows how I'm doing before me. He has never been trained but have had him since he was weeks very smart and I believe they gravitate towards people who are ill sad depressed

Dogs are great! Even the untrained ones provide vital service. My grand dog came over the other day. He’s took off at a dead run from the back door, jumped up on my bed, and nursed me through a particularly bad day.

Totally agree Phil. He doesn't even get mad when he's water goes everywhere but he's bowl