Throwing Up & Diarrhea in Dogs

There can be many reasons why a dog is throwing up and has diarrhea. Vomiting and diarrhea can happen from eating something bad or, in the worst case, be symptoms of a life-threatening illness. Parasites, viral or bacterial infection and cancer are just some of the reasons why a dog may be vomiting and have diarrhea that persists beyond a few days. While only a veterinarian can accurately diagnose your dog's health, there are some things that you can observe that will help in determining the severity of your dog's condition.



A dog vomits when its stomach or first part of the small intestine is irritated. In an attempt to get rid of the irritating substance, the muscles reverse their movement to push the material back up rather than down the digestive tract. Sometimes, the vomiting is more severe because the irritating object gets stuck in the digestive tract, causing the muscles' natural movement to stop abruptly and push up violently. Diarrhea usually happens when there is irritation in the lower part of the small intestine and the large intestine. The irritating item causes the muscles to contract faster, which forces feces to come out before excess water has been absorbed and digestion is complete. The most common cause of dogs vomiting and having diarrhea is eating irritating items such as greasy table foods, leaves, sticks, dirt and trash. The vomit and feces will usually contain bits of the irritating item. Vomiting and diarrhea from eating the wrong thing usually resolves itself within a few days. Treatment involves hydration and avoidance of the irritating item in the future.


A more serious cause of vomiting and diarrhea in dogs, particularly young dogs, is the presence of parasites such as roundworms and whipworms. Most dogs have parasites some time in their lives from contact with infected substances, but immunity keeps the parasite population under control. Sometimes, stress or illness reduces the dog's natural immunity and allows the parasite population to increase. When a dog has roundworms, its vomit and diarrhea may contain some of them, which look like white coiled spaghetti. Whipworms are harder to detect because they fasten themselves to the wall of the gut and lay fewer eggs, which makes finding eggs in the feces more difficult. A dog with a whipworm infestation will usually have urgent and painful diarrhea where the feces are bloody and look like mucus. The veterinarian may prescribe a variety of deworming drugs, such as Drontal Plus and Panacur, which is taken in rounds.

Viral or Bacterial Infection

Viral infection of the digestive tract can also cause dogs to vomit and have diarrhea. A dog can pick up a viral infection from contact with an infected dog, secretions or simply being in an environment where the virus is still living. Types of viral infection that cause vomiting and diarrhea include canine distemper and canine parvovirus. Vomiting and diarrhea may also be caused from a bacterial infection, such as salmonellosis and staphylococcus. Symptoms beyond vomiting and diarrhea vary depending on the specific type of infection but may include loss of appetite, fever, lethargy and abnormal discharges. Treatment likewise depends on the infection but may include antibiotics, hydration and intravenous feeding of food and vitamins.


In older dogs, long-lasting vomiting and diarrhea can be symptoms of cancer. Cancer can reach the digestive tract and lead to irritation, causing the dog to vomit. Tumors may cause vomiting and, if located in the lower intestine, diarrhea. As with humans, the most obvious symptoms of cancer include the presence of a lump, swelling, a persistent wound and abnormal bleeding. Sometimes, at least in the early stages of cancer, there are no obvious symptoms. Vomiting and diarrhea that persist beyond a few days, especially if accompanied by one or more of the classic cancer symptoms, should be quickly checked by a veterinarian. Treatment options include radiation, chemotherapy, surgery and anti-cancer drugs.