Oddly enough, there's no known cause for HGE. Also, chances of a recurrance are very slim. There's also no test for it other than ruling everything else out. Seemed kinda weird when the vet told me, but all of the info I can find online echoes what she said. They looked everywhere for a cause.... Kidneys, liver, CBC, fecal swab, x-rays on her gut, thyroid, etc. At least after this is over I'll know that she's in really good shape. My other Rottie looked all over the house for her sister when I got back from the vet, now she's acting really depressed and won't leave whatever room that I'm in. I feel sorry for the girl.