Not completely on point, but somewhat related;
When we were younger, my wife and I had Newfoundlands. The breed are wonderful dogs. We got our first from a local kennel, who had connections to another breeder back east. As we understood, the breeder back east desired to continue the bloodlines of the famous "Dory O" kennels out of Newfoundland. Seemed like a noble cause, but as it turned out, the breeder back east was just another money grubbing scheister lawyer that was primarily in it for the money. Anyway, both breeders got back in touch with us when our Newfie was about four years old and wanted to breed him. OK, so we were requested to take him to the vet for OFA hip X-Rays as part of the documentation of the breeding/bloodline process. Our Newfie weighed 175 pounds. The anesthesia dosage charts only went to 50 or 60 pounds. So what does the vet do ? He simply "tripled the dose" and promptly killed our dog.
Large breeds do not have to have that much anesthesia. I have been told that our dog should have been given only about 1.5X the amount that would be used for a 60 (or so) pound dog. If you have a big breed, you take him/her to the vet, please make sure your vet is up to speed on the subject of anesthesia for big breeds. We were not and were heartbroken.