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My Cassie dog got sick all of a sudden and would not eat, the second day i took her to the vet and he said she had a blockage and put her stool softener and antibiotics, for the next three days she was able to eat and be a normal puppy and all of a sudden she wouldnt come out of her dog house. I took her back to the vet and they said they had to do emergency surgery, her small intestine was eating itself like a telescope, they removed five inches of dead small intestine and she started eating again, the night after surgery she died in her sleep, the vet does not know what caused this. Any one else see this, she was half blue tic,quarter black and tan quarter plott

It's called intussusception.
http://www.medicinenet.com/intussusception/article.htm

Happens most often in infants, not sure on the occurence in dogs. For the most part is is ideopathic, meaning there is no known cause. Obviously something casues it, they just don't know exactly what.

Your pup was either likely correctly diagnosed too late, and the ischemic bowel resulted in sepsis and irreversible organ failure, or, there was a post op complication, like a blood clot, etc, that caused her death. It is an uncommon condition, and it would be hard to fault your vet for overlooking such a condition on the original visit. Were you offered an xray??
Everytime we take our dogs to the vet, we have the option of agressively or conservatively treating / diagnosing a suspected illness. Xray, CT scan with contrast, blood work, would all have helped with an early diagnosis. Unfortuneately, they do cost $$.

Either way it sucks. Sorry for your loss.