I am very sorry about what happened with your girl. My Misty passed away from Hemangiosarcoma too. In her case we did get some warning. But it is true that sometimes Hemangiosarcoma can take them very suddenly indeed, and can often be the cause of many inexplicable deaths.
With this cancer they sometimes show no signs of being ill before total collapse.
Dear backwoods rocker, I am so very sorry for your loss. We lost our precious girl suddenly in 3/2014. I immediately called the vet as I was afraid she had been poisoned as she died in the backyard. The vet thought a sudden death in our 8 year old might be hemangiosarcoma of the spleen or heart. Necroscopy found it was exactly that in her heart. This was a cancer of the blood vessels, and nothing could have been done. Sudden loss is so very hard. (((HUGS)))
Dear backwoods rocker, I am so very sorry for your loss. We lost our precious girl suddenly in 3/2014. I immediately called the vet as I was afraid she had been poisoned as she died in the backyard. The vet thought a sudden death in our 8 year old might be hemangiosarcoma of the spleen or heart. Necroscopy found it was exactly that in her heart. This was a cancer of the blood vessels, and nothing could have been done. Sudden loss is so very hard. (((HUGS)))
This must be a common occurrence and common for people to look up the sudden death of their dog from feelings of guilt like me. Our Border Collie Maddie died suddenly today at exactly 4pm Central time. She was eating, drinking water and enjoying treats like always. She had laid down below our TV as usual to take her after dinner nap. My husband was 4 feet away from her and I was cooking when I heard a weird whimper like she does when she is dreaming heavy. Except this whiney whistling whimper sounded different and high pitched than the dreaming type. I ran into the den to see what was happening and my husband asked me if the dog was dying!!! I yelled her name loudly over and over, Maddie! Maddie! and she never lifted her head made another sound. She took two gasping death breaths and was gone. She never acted sick other than licking a lot for the last 4 days like she had maybe a urinary infection. I checked to see why she was licking so much and noticed that she was doing it due to urine leakage so we were heading to the vet on Monday. We have had her for 10 years and we are not sure if she was 3 or 7 when we rescued her from a kill shelter in 2005 so she was old and was diagnosed with heartworms when we got her. Even though she was getting old it is none less shocking and heartbreaking when your dog suddenly dies like this when they are otherwise acting "normal". We had to put her in the deep freezer until we can get to the animal crematory on Monday. She dies 2 hours after they closed today. We live in the Texas Hill Country and cannot dig a hole to bury her in. We have limestone rock in every spot we tried to start digging. It has been a really bad day, my lovely cousin Donna also died this morning, we were dealing with those feelings and then our dog died. A very, very odd day. Maybe my cousin needed a pup in heaven!
This sudden death is all so horrible for us humans. At least our beloved pets didn't suffer much. My fiance' and I just lost our 8 month old Rhodesian Ridgeback pup this past Monday evening, and we are devastated. Her death was like a lightning strike out of the blue. She was a beautiful, happy and apparently healthy pup. Before we knew what was happening, she was gone. The vet suggested undiagnosed heart failure, but her puppy check ups had all passed fine. He said the necropsy would cost us "almost as much as the pup purchase price", which was $1800 in our case, so we declined. It wouldn't bring our Bella back, and we can't go further in debt for something like this. My fiance' and I almost feel the little girl had a stroke or aneurysm since she went almost instantly and her heart had checked good. While this is not supposed to happen, it does... take nothing for granted, and take lots of pictures!
My scottish terrier, who was 7 years old, 8 months, 2 weeks, died suddently 12/29/14. He was not ill, showed no signs of injury, no vomit, no bowel movement...he was found lying still on the grass in our backyard. He was let out of the house to get some sun and to continue his barking at the UPS man who was ringing our doorbell. Our daughter found him lying there with his eyes opened and mouth partially open. We just don't know what could have happened. He goes to the vet, takes his monthly meds for ticks/fleas, eats regularly. He was a great dog; had him as a puppy...very smart, energetic, special to us. He is sorely missed! I haven't been able to eat for 3 days now. Today we had a UPS delivery and no barking; it hurts a lot but I know he is at a much better place. I'm trying to focus on being thankful for the good times we had together and the time we had. He did not suffer but went peacefully; his time was up. :(
From your description of what happened, it does sound like it could have been either a cardiac or cerebral event, but the only way to tell for sure what it was would be to have your vet perform a necropsy (autopsy). Many people don't want to put their pet through this, after all it won't bring them back and it does cost money to have done. If you feel it would give you closure, however, contact your vet and arrange to have it done.
Again, my most sincere sympathies to you on your loss.
Ghilly