intestine issues

I am very concerned about recent events that occured over the weekend and I need some advice. On Friday April 13th I left my house to go to the dentist. Had dinner with some friends came home about 9:30p.m. When I arrived My 16 month old bullmastiff was acting very strange. Lathargic not moving well (limping) not wanting to play or acknowledge anyones presence disoriented vomiting and he had loose stool. After continuously checking him out top to bottom I decided it was time to call the E.R. Vet. We arrived at the vets office shortly after 10:30 p.m. He had fever and she said his intestines were swollen and he most likely had an infection. She gave him a morphine like pain shot and a shot of antibiotics. Told me if he wasnt better the next day to bring him back. Sure enough the next day no different. I called and told them he was no better he was getting worse by then he could no longer barely stand. So we took him back. The other vet saw him and said maybe he had a blockage in his intestine that I needed to take him home and give him this bayrium type medicine and bring him back at 8a.m. Sunday morning for X-RAY and ultrasound. The vet then gave him another pain med shot and another antibiotic shot. Needless to say Sunday morning when I awoke to take him back to the vet he was dead in my bathroom. I called the vet we took him in for an autopsy. The cause of death was heart attack brought on by a ruptured intestine...a chicken bone had been lodged in his small intesting note: I did NOT allow my dog to eat chicken bones, so I am baffled on how he managed to get it. I was told by the vet that even if they would have found the blockage on Friday there was no saving him. Is this true? Shouldn't they have performed an ultrasound that first day? I have read articles how animals with blocked or ruptured intestines have had surgery to repair the intestine. I am devestaed at the loss of my "child" and now I am feeling betrayed by the vet who vowed to me that he would do whatever he could to save my baby. I just want some answers on could this be a case to where by the time I noticed something was wrong was it too late, or could something have been done? Thank You for your help.