Why does my dog a bloody diarreha?

Ok so I rescued my new dachshund from the animal shelter like 5 days ago. He's been doing great so far. But I've noticed that he's been having diarreha and it's been bloody. I just took him to the vet for a wellness exam, and the vet said he was healthy. I just dont understand why he's got bloddy diarreha. Can someone plz help me??

I'll never ever begin to understand how someone can have a dog pooping blood... and instead of taking the dog to a DOCTOR (ie: veterinarian)... no... the clueless owner has to ask a bunch of strangers on an internet board what to do....

From a shelter, this could be parvovirus or coronavirus (or severe worms). Schedule with the vet again and take in a "poop sample". This is particularly important if the diarrhea is more foul smelling than would be expected or the blood is dark, not fresh (sometimes, fresh red blood just indicates the dog is straining to go and his backside is raw). From my experience with rescue dogs, a dog can be "fine" one day and the next be showing symptoms of parvo. If you don't trust the vet you saw, choose another. Look on the internet for a local kennel club if you need a vet recommendation. Usually show dog folks will know who the best vets in your area are.

check if your dog has eaten any clothing or tissue paper but don't worry dachshunds usually eat stuff like that but it will pass sooner or later you just need to check on your dog every once and a while to make sure he doesn't eat anything like clothes or tissue paper again because it is very hard for a dachshund's stomach to break down stuff like that just make sure he has a little more water then usual and he will be fine

you need to take him back to the vet...how long has be been like that?

VETS!!!! NOW!!!!!!

WHY ARE YOU WASTING YOUR DOGS TIME ON HERE WHEN WITHOUT QUESTION YOU SHOULD BE AT THE VETS!!!!!!!!