Yeah, Sherri, it's super-scary in old dogs! Rowley had HGE and he was back to his old self in about three hours. Rudy had it and he had to spend the day at the vet, getting sub-q fluids. Sunny is at the e-vet overnight so he can be monitored and get not only fluids but IV metronidazole, and he has to go back to the regular vet tomorrow -- the soonest he can come home is tomorrow night. Those old guys, their bounce-back-ability isn't what it once was!
The bloodwork showed nothing terrible or scary. BUN is a little elevated but not much, and consistent with dehydration from HGE. Nothing indicates kidney disease or failure. The e-vet will get a urine sample from him and run a urinalysis and if they find a UTI, he will get abx, I would think Clavamox? -- for ten days. I do think he will make a full recovery from this but it will take time. Poor Sun, he was not a happy camper when I left him at the e-vet, but a tech from our clinic was there and she was taking him back to a kennel to get his meds started.
Judy, AFAIK they hardly ever know what causes HGE, it's really just diarrhea gone berserk, as my vet put it. It can be caused by a virus, but it's most often just a routine gastrointestinal upset that turns into major gi irritation and spirals into HGE. The resultant dehydration and drop in body temp is what does the damage.