Parvovirus, commonly known as parvo, is a highly contagious viral disease that can affect dogs. Parvo affects a dog’s gastrointestinal tract and in rare cases, its cardiac system. Dogs are most commonly exposed to parvo from contaminated feces of other dogs. An infected dog sheds viral particles in its feces before showing any symptoms, which allows the virus to spread quickly between dogs. This has led to some confusion around whether dogs can carry parvo without being sick from it themselves.
Overview of Parvo in Dogs
Parvo is caused by the canine parvovirus type 2 (CPV-2). There are three main strains of the virus: CPV-2a, CPV-2b, and CPV-2c. All strains are extremely contagious and potentially fatal in dogs.
The virus attacks rapidly dividing cells in a dog’s body, most severely affecting cells in the intestinal tract. Destruction of the intestinal cells leads to the common symptoms of parvo, including:
- Vomiting
- Bloody diarrhea
- Loss of appetite
- Lethargy
- Rapid weight loss
- Dehydration
In rare cases, the virus can attack the heart muscle cells, leading to acute cardiac failure.
Parvo has an incubation period of 4-14 days. This means after a dog is exposed to the virus it will take 4-14 days for symptoms to develop. During this incubation time the dog may be shedding viral particles in its feces while appearing outwardly healthy.
Can Dogs Carry Parvo Without Getting Sick?
The short answer is yes, dogs can carry parvo while not showing symptoms themselves.
During the incubation period, an infected dog is shedding viral particles before the virus has multiplied enough to make the dog ill. So during this time, the dog is infectious to other dogs while appearing healthy.
Additionally, some dogs may be exposed to parvo but have immunity from vaccination or previous infection. These dogs may have enough antibodies to prevent the virus from making them sick, while still carrying and shedding low levels of virus particles.
However, it is less common for a dog to remain a long-term carrier of parvo. Once a dog recovers from parvo, the virus is typically cleared from their body within 10 days. In rare cases, a dog can shed the virus for up to 6 weeks after recovery. But there is little evidence to suggest dogs become persistently infected or lifelong carriers of parvo.
Risk Factors for Parvo in Dogs
While any unvaccinated dog is at risk of contracting parvo, certain factors increase a dog’s risk of exposure and infection:
Age
Puppies under 4 months old are most susceptible as they have no vaccine protection against parvo. The virus attacks rapidly dividing cells, so the fast cell turnover in puppies’ developing intestines makes them especially vulnerable. Over 70% of parvo cases are puppies under 1 year old.
Incomplete Vaccination
Without a complete series of parvo vaccinations, dogs are unprotected against the virus. Different vaccines provide protection after a different number of doses, so it’s important to follow the exact vaccination schedule recommended by your veterinarian.
Intact Male Dogs
Intact male dogs are twice as likely to contract parvo. It is believed their increased investigative behaviors and roaming puts them at greater risk of encountering contaminated feces. Neutering eliminates their motivation to roam and mark territories.
Multi-Dog Homes
The more dogs in a household, the greater the risk of parvo exposure. Even one infected dog can quickly spread parvo to other household dogs. Strict biosecurity and isolation procedures should be followed with symptomatic dogs.
Unhygienic Conditions
Kennels, dog daycares, shelters, and parks can be hotbeds for parvo if proper cleaning and disinfection protocols aren’t followed. The virus can survive for months in the environment, so contaminated soil or feces can serve as a source of infection long after an infected dog has left the area.
Diagnosing Parvo
If you suspect your dog has been exposed to parvo, see your veterinarian immediately. They can run diagnostic tests to check for the presence of the virus.
Physical Exam
A full physical exam may reveal symptoms consistent with parvo, like fever, lethargy, vomiting, and diarrhea. Your vet will assess dehydration levels and check other vital signs.
Fecal Tests
Your vet can test a fecal sample for the presence of parvovirus through:
- ELISA: This rapid test can provide results in under an hour.
- PCR: The polymerase chain reaction test detects parvo DNA. It is extremely accurate but takes 1-2 days for results.
Blood Tests
While less common than fecal tests, blood can also be analyzed for parvo antibodies to confirm infection.
If parvo is confirmed, your vet will recommend hospitalization and treatment to combat dehydration and preserve intestinal health. With proper care, most dogs recover fully within 1-2 weeks.
Preventing Parvo Transmission
To prevent infected but asymptomatic dogs from unknowingly spreading parvo, follow these guidelines:
Vaccinate All Puppies and Dogs
Ensure your own dogs complete their entire vaccine schedule according to your veterinarian’s recommendations. Avoid taking puppies to high-risk areas until at least 1 week after their final parvo vaccination.
Carefully Choose Daycares and Kennels
Select facilities that follow stringent biosecurity and sanitation protocols. Ask about their parvo prevention policies.
Clean Up After Your Dog
Always pick up and properly dispose of dog waste, especially in public areas. The parvo virus can survive for years in soil contaminated with feces.
Limit Contact with Unknown Dogs
Avoid dog parks, daycares, and boarding until puppies are fully vaccinated. Be cautious allowing your puppy to meet neighbor dogs; their vaccine status is likely unknown.
Isolate Symptomatic and Exposed Dogs
Dogs showing any signs of parvo or known parvo exposures should be immediately isolated from other dogs. Thoroughly clean contaminated surfaces with bleach. Wash hands and change clothes after contact.
Talk to Your Veterinarian
Notify your vet if your dog becomes ill or if you’re concerned about a parvo exposure. They can advise the best diagnostics, treatment, and containment protocols.
Conclusion
While uncommon, it is possible for dogs to carry parvovirus while displaying no symptoms. This typically occurs during the incubation stage of infection or in vaccinated dogs with enough antibodies to fight off disease. However, these dogs can still shed viral particles in their feces and infect other dogs. Strict biosecurity measures and vigilance are needed to prevent asymptomatic carriers from spreading parvo. But with proper vaccination protocols, safe socialization, and good hygiene, parvo can be prevented in healthy dog populations.
