5 Signs of Parvo in Dogs

Jennifer Coates, DVM
Feb 19, 2016
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Signs of Parvo: What to Look For

By Jennifer Coates, DVM

Parvo, officially known as canine parvovirus, or CPV, is a highly contagious viral disease. Dogs who are sick or recovering from parvo pass incredibly large numbers of the virus in their feces, and virus particles can survive for months in the environment. Susceptible dogs are infected orally when they come into contact with a contaminated area. Puppies and young dogs who have not received all of their vaccines are at highest risk for developing parvo.

That’s the bad news. The good news is that parvo does not have to be deadly. If dogs with parvo receive prompt and appropriate veterinary treatment, many can be saved. 

Learn the signs of parvo in dogs, so that you can work with your veterinarian on treating and beating the parvo disease. 

Poor Appetite

Often, one of the first signs that a dog is getting sick is a loss of appetite. This is especially true with parvo. In the early stages of the disease, the virus invades and starts to replicate within the lining of the intestinal tract and other parts of the body. The immune system is also gearing up to respond. All of this can lead to a fever, low energy levels, and, most notably, a loss of interest in food. 


Most dogs with parvo vomit. Initially the vomit may contain remnants of the dog’s last meal, but as vomiting continues all that comes up is a foamy mucus that may contain bile, a yellow-brown digestive fluid, or blood. Blood can be bright red or partially digested, which gives it the appearance of coffee-grounds. As dogs with parvo become dehydrated, they may try to drink, but anything they take in typically comes right back up.

Diarrhea – Possibly with Blood

Diarrhea develops as the virus and the resulting immune response damages the lining of the intestinal tract. The intestines can no longer absorb water and nutrients and become leaky. Fluid from the body can pass into the intestines, worsening diarrhea and dehydration. Blood vessels within the intestinal wall may be damaged, causing blood to become visible in the stool and providing a route for bacteria to enter the dog’s circulatory system.

Damage to Other Body Parts

Parvovirus doesn’t just invade the lining of the intestinal tract, it also attacks other rapidly dividing cells. In young puppies, this can include heart muscle, leading to chronic heart disease or sudden death. Bone marrow, which produces important parts of the immune system, can also be affected. The combination of a weakened immune response and bacteria entering the bloodstream through a damaged intestinal wall often results in bacterial pneumonia for dogs with parvo.

Preventing Parvo

Most cases of parvo can be prevented with a series of vaccines that start when a puppy is around 7-8 weeks old. Puppies receive three or four parvo vaccines roughly every three weeks until they are 3-4 months old. Dogs should be revaccinated one year later. Then most dogs only need a parvo booster every three years, or they can have an annual vaccine titer to check their immunity.

For serious and potentially fatal diseases like parvo, the benefits of prevention always outweigh the costs associated with illness and treatment.

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