Parvovirus in Dogs: Symptoms and Prevention

Parvovirus, also known as Parvoviral Enteritis or “Parvo” for short, is a virus that can cause severe infection in puppies and dogs. It invades and destroys rapidly growing cells in the intestine, bone marrow, and lymphoid tissue resulting in nausea, vomiting, and severe hemorrhagic (bloody) diarrhea.

The invasion of the bone marrow cells causes a decrease in the white blood cell count, leading to increased susceptibility to bacterial infections and potentially to a shock-like condition called endotoxemia. The disease can vary from mild to fatal if not properly treated.

Is Parvo Contagious?

Parvovirus is extremely contagious to other dogs. Infection is generally attributed to the ingestion of material contaminated by dog feces and can occur when a dog smells or licks the ground.

Direct contact with another dog is not necessary for infection. Parvovirus is shed in the feces of infected dogs for approximately two weeks after initial ingestion and can live in the environment for years. The virus is species-specific and is not contagious to cats or humans.

Which Dogs Are Most at Risk of Catching Parvovirus?

Dogs at the highest risk for infection are unvaccinated puppies or those who have not yet completed their vaccine series. It is most common in dogs less than 8 months old. Especially susceptible breeds include Doberman Pinschers, Rottweilers, German Shepherds, Staffordshire Terriers, black Labs, and Dachshunds.

Dogs of all ages can be infected, but puppies and younger dogs are most susceptible. Intact male dogs may also be susceptible for unknown reasons. Unsanitary and/or overcrowded kennels may increase the chance of infection.
Parvovirus is an acute and serious disease, not a chronic condition. Virtually all cases need proper diagnosis and hospitalization. If your dog is having active symptoms, it is important to see your veterinarian. Parvovirus can be fatal if not properly treated.

Symptoms of Parvovirus in Dogs

Clinical signs in dogs are seen 3 to 14 days after exposure to the virus.

Symptoms may include:

• Vomiting
• Diarrhea (often containing foul-smelling blood)
• Loss of appetite (anorexia)
• Depression and lethargy
• Fever
• Weakness

Diagnosis of Parvoviral Enteritis in Dogs

Diagnosis is usually based on clinical signs. Diagnostic tests are needed to recognize parvovirus and exclude other diseases.

Tests may include:

• Complete medical history and physical examination
• Testing feces for the presence of the virus
• Blood tests and abdominal X-rays to determine the severity of the infection or exclude other causes of the symptoms
• Fecal analysis to evaluate for concurrent parasites

Treatment of Parvoviral Enteritis in Dogs

Your veterinarian will probably recommend hospitalization. Therapy is dependent upon the severity of the clinical symptoms and is aimed at treating the dehydration, controlling vomiting and diarrhea, and preventing secondary infection. If the bacterial infection can be prevented and dehydration treated, clinical signs will usually resolve in 2 to 5 days.

Therapy may include:

• Intravenous (IV) fluid therapy, antibiotics and/or other drugs used to replace electrolyte and fluid losses and control nausea and vomiting.
• As an alternative to hospitalization with IV fluids, outpatient treatment with antibiotics and drugs to control vomiting may be attempted. In general, the survival rate is lower with this therapy compared to dogs that are hospitalized with IV therapy and care.
• In very severe cases, referral to a 24-hour critical care center may be recommended.

Home Care for Parvo

At home, allow your dog to rest and regain their strength. Once vomiting and diarrhea have stopped, encourage water intake. Offer your dog a small amount of water and a bland diet. Your veterinarian may recommend a prescription diet.
It takes a few days for stool to normalize. Nevertheless, it is important that you pick up feces and keep the environment clean. It is likely that the feces will contain the virus and other dogs may contract the disease.
If your dog is not eating or drinking, is continually tired, vomiting, and/or still has diarrhea, call your veterinarian.

Preventive Care for Parvovirus

Prevention is possible by vaccinating your dog regularly to help prevent infection. (NOTE: Immunity to parvovirus develops after infection, but it is necessary to schedule booster immunizations (“shots”) with your veterinarian to protect from other viruses).

It is now recommended that the last vaccine in the puppy series be at approximately 20 weeks. Previously, the last vaccine for parvovirus was recommended closer to 16 weeks.

Parvovirus in vaccinated dogs is extremely rare, but not impossible.

Keep your dog away from the fecal waste of other dogs when walking along neighborhood streets or parks. If your dog leaves their own “deposit,” be sure to remove it and dispose of it at home.
You should also minimize contact of unvaccinated puppies with other dogs that may be sick or unvaccinated. This should include avoiding areas where other sick dogs may have been (parvo can live in the environment for 2 years). Your dog is most at risk until fully vaccinated (usually 20 to 24 weeks of age).