Myasthenia gravis

I am grieving the loss of my beloved companion who was euthanized on May 18, 2011. He seemed healthy for his age (10 y/o plus)with the normal signs of aging: retinal atrophy, arthritis in front legs, some muscle wasting in his hind legs, and 6 or 7 non-cancerous fatty tumors. He was taking 1 Dasuquin and (2) 50mg Tramadol per day with excellent results. He had some trouble getting in the car without a boost and hesitated ascending stairs but could still manage with some coaxing. I would like your professional insight as to the manner of his diagnosis and treatment prior this death. Here is a timeline leading up to May 18.
My question is following the timeline.

February 2011: I research canine dental cleaning and schedule two dental exams. Both recommend that scaling is necessary but not imperative. I've brushed his teeth for years. I'm uncertain if I should proceed due to his age and needing anesthesia for the procedure.

April 26: He yelps when eating a small milk bone, and days later when given a piece of pizza crust. He shuns "treats". I examine his gums and teeth. He yelps when I touch his right jaw (no bleeding or visible signs of decay or cracked teeth).

May 1: I take him to vet for a blood panel and dental exam. The blood work is negative for infections, liver enzyme is a bit elevated. He yelps again during the exam but vet can't see any dental abnormalities. His weight is 86lbs.

May 3, 2011: Follow-up, head x-ray and consultation with his regular vet. His vet explains that she cannot find any cracked or abscessed teeth - if anything they look fine. She suspects Myasthenia Gravis and prescribes Prednisone (20mg) for 50 pill duration. She explains that it's an aggressive dosage: 2 pills (twice a day) for 4-5 days then 1.5 pills (twice a day) for 3 days then 1 (twice daily) for 3 days then 1 daily for 7 days then 1 every other day for 7 days. We decided to cancel and reschedule dental cleaning. I left feeling good about his prognosis.

May 7: He is taking Pred and Tramadol as prescribed. It's his 11th Birthday and he is eating like a horse, drinking alot of water and urinating frequently.

May 14: He chokes while eating this morning. We go on a road trip and he seems lethargic. I call to schedule a vet appointment for next morning.

May 15: He looks worse. Vet gives him IV fluid therapy, Cerenia, Pred injection, x-rays of chest. X-ray shows esophagus is enlarged and he has some fluid in his lungs. Vet gives Baytril 136mg (2 per day) That evening he eats and drinks some. He now weighs 75.3 lbs. I'm concerned.

May 16: I resort to feeding him by hand. He has some appetite but regurgitates all food and water. He staggers when walking. I'm conflicted - he is getting worse?

May 17: He won't eat. I take him to vet at 3PM. He receives fluid therapy, Pred injection, an injection for nausea. His vet is surprised by weight loss, and explains that his condition is deteriorating. He has (pneumonia). She explains his prognosis is grim. He refuses to eat at home.

May 18: He will eagerly drink water but will not eat. I even tried a McD's cheeseburger which he never refused. His breathing is labored, heart rate is rapid, coughing water and mucus, and he cannot stand at all. I decide that I can no longer see him suffer and take him to the vet.
At 3PM He passes peacefully.

Dear Doctor, my dog was the smartest most loving pet I've ever owned and my grief is consuming me. It's unbelievable that he would go from a seemingly healthy older dog to death in less than 1 month! I've read about Myasthenia Gravis/Megaesophagus and come to my own conclusions but I need closure so I can move past grief, blame and into acceptance.

Would you would make the same conclusions, decisions and prescribe the same medications (Prednisone 20mg) and (Baytril 136mg) in my dog's case? I have a schedule of date/times/and dosages if needed. Let me know if you need further clarification.

Thank-you for your advice!

Dear Dr. Marie, Thank you for your quick reply. I feel better knowing that everything was done to extend his quality of life. Now I can close this chapter and grieve properly.

I have two more clarifications:

1. Could he have had MG for months with no outward signs? I only noticed a behavioral change in April when he yelped, was tentative when eating hard treats, and seemed to lose fullness in his temples. I ask this because of the sudden nature of his megaesophagus and there was no other "signs". He was always a good eater - Gotta love Labs!

2. Are my questions and your replies able to be viewed by others? I would prefer that not be the case or could you remove his name if that is the case?

I rescued him but he repaid me a thousand times with love and devotion.
Thanks again.

Absolutely, you may publish my questions and your answers w/o names. I hope this information helps others with a similar situation.

You may title this article: My lab was diagnosed with Myastenia Gravis and Megaesophagus and died