Parvovirus in Dogs and Why Vaccination Matters

Parvovirus in Dogs and Why Vaccination Matters

What is Parvovirus?

Parvovirus is a highly contagious viral disease that affects dogs—especially puppies. It's caused by a tiny, tough virus that can survive in the environment for up to 8–12 months.  

Dogs infected with parvovirus shed the virus in their diarrhoea, which can contaminate everything, surfaces, bedding, feeding bowls, grass and concrete. Once the environment is infected, it becomes a serious risk to other unvaccinated dogs.

A Quick History of Parvovirus

Parvovirus was first recognised in dogs in the late 1970s. Before vaccinations became available, it spread rapidly and caused many deaths, particularly among puppies.

The first parvovirus vaccine was developed in 1979, and vaccination has since become very effective at preventing infection and disease. Even today, though, we still see cases of parvo—especially in unvaccinated pups. It's a serious illness that causes:

  • Loss of appetite

  • Vomiting

  • Bloody diarrhoea

  • Rapid dehydration

  • Weakness

  • Death

Treatment can be intensive and costly, and sadly, some puppies don’t survive despite the best care.

Why Vaccination Is So Important

Parvovirus vaccination is almost 100% effective at preventing the disease when given correctly.



Puppies are especially vulnerable to parvovirus, and here’s why:

When a pup is first born and suckles from their mum, they receive temporary antibodies from the first milk (colostrum). This is called passive immunity. These antibodies protect the puppy for a short time—but they gradually wear off over the first few months (indicated by the red line on the graph maternally derived antibody MDA).

To build long-lasting protection, we rely on vaccines to stimulate the puppy’s own immune system to produce antibodies without causing diseases (called active immunity). But here’s the tricky bit:

Maternal antibodies interfere with the response to vaccination.  Vaccination is only effective once maternal Ab has dropped to a certain level.  This level is lower than the antibody level that protects the pup from parvovirus.  There is a ' danger window' where the pup is not protected by the antibodies from mum and they don't yet respond to parvovirus vaccination.  


The Vulnerability Window (Why Timing Matters)

Let’s look at this in action:

  • Puppy 3 (yellow) didn’t get much colostrum so has lower maternal antibody levels. Puppy 3 is vulnerable to parvovirus infection early (around 4 weeks) and will respond to a vaccine from 8 weeks of age.

  • Puppy 2 (orange) has moderate level of antibodies from colostrum and becomes vulnerable to parvovirus infecton around 8 weeks and will respond to vaccination from 12 weeks.

  • Puppy 1 (red) got the most colostrum and has the highest maternal antibody levels.  Puppy C isn’t vulnerable to parvovirus infection until 12–13 weeks of age and won’t respond to a vaccine until 16 weeks of age.






There’s no easy way to know which window your puppy is in, so the safest approach is to vaccinate every 3–4 weeks, starting at 6–8 weeks of age until they're at least 16 weeks old.

Vaccination Schedule

✅ Puppies: Vaccinate every 3–4 weeks from 6–8 weeks of age until 16 weeks
✅ Booster: One more booster at 6–12 months 
✅ Adults: Boosters every 3 years

Until your puppy is fully vaccinated, it's best to avoid public places like dog parks, footpaths, and pet shops—anywhere the virus might linger.

Balancing Safety and Socialisation

It is important for puppies to be socialised with the most important period being between 3 and 16 weeks of age.  This critical window overlaps with the puppies vulnerability to parvovirus. There’s a delicate balance between keeping your pup safe and helping them grow into a well-adjusted dog. 

The NZ Veterinary Association chart is a useful overview: https://nzva.org.nz/assets/For_the_public/Puppy_Socialisation.pdf

What If a Puppy Has Had Parvovirus?

If your home has had a case of parvo, thorough cleaning is essential:

  • Dispose of faeces and vomit carefully to avoid spreading the virus.

  • Disinfect surfaces, bowls, and bedding using a diluted bleach solution (approx. ½ cup bleach to 4L of water). Let it sit for 15 minutes before rinsing.

  • Keep in mind: it’s very hard to sanitise carpet or grass. Homes with a recent parvovirus case remain high-risk environments for unvaccinated puppies for up to a year.

In Summary

Parvovirus is a serious, highly contagious disease that’s best avoided through timely vaccination. By following the correct vaccination schedule, keeping young pups away from high-risk areas until they are fully vaccinated and maintaining good hygiene, you’re giving your dog the best protection.

💉 Vaccination saves lives—especially for your growing puppy.

Have questions or need to schedule a vaccination?
Contact us.










 



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