What if my dog has worms and they go untreated? - Advanced Animal Care

We can usually see some GI issues—vomiting, diarrhea, inappetence, things like that—that tell you that your dog has an upset stomach. If left untreated, especially in smaller dogs with hookworms, we can see what's called hookworm anemia. And that is something that can end up being fatal, so you always want to make sure that if your dog does have diarrhea or you see worms, you're getting to your vet pretty quickly.