Parvo in Dogs: Evidence-based Look at Canine Parvovirus

Parvo in Dogs - What You Need to Know About Canine Parvovirus

Parvo in Dogs - What You Need to Know About Canine ParvovirusParvo in dogs, or its more accurate yet less known title Canine Parvovirus (CPV), is a highly contagious viral disease found in dogs, which can be fatal.

Studies have shown that parvo in dogs commonly causes acute gastroenteritis [1], an intense inflammation of dogs’ intestines and stomach, among other serious problems.

Parvo can be contracted by dogs of any age, but is most often seen in unvaccinated puppies and in very old dogs [2].

What is parvo in dogs?

Parvo as a virus is not exclusive to dogs. There are many different types of parvoviruses out there – each mammalian species seems to have its own.

Canine Parvovirus specifically, however, is a very common disease among the dog population. It is a very hardy virus that can survive in the soil for months, and in some cases, even years [3]. It can also be passed on from dog to dog, especially from contact with feces. Other sources are dirty flooring and kennel equipment in dog shelters, pet stores and breeding kennels.

Part of the reason that Parvo persists in the environment outdoors is because of wildlife. Canine Parvovirus can infect other members of the canine family, such as wolves, coyotes and foxes [4]. If these guys live in your area, they can spread the disease quickly and “silently.”

Is my dog at risk of contracting CPV?

Parvo in dogs has become a disease that almost exclusively affects puppies and young dogs [2, 3]. Some very old dogs may be at risk too, especially if their vaccination status is unknown, or if they suffer from a compromised immune system.

Puppies are at the most risk because the immune protection they received from their mother wanes by 6-8 weeks of age. Puppies under 16 weeks of age also have not had their full vaccination series, which means that they have only partial immunity [5].

Bottom line: Puppies are most prone to CPV, but if your dog is not vaccinated for Canine Parvovirus, he is at risk of contracting the disease regardless of age.

Signs and symptoms of parvo in dogs

There is a 3-7 day period between Parvo exposure, and your dog becoming physically ill.

When the virus enters the dog’s body, it seeks out the most rapidly dividing cells around. This is normally within the lymph nodes in the dog’s neck. The parvovirus replicates there, and spreads throughout the body.

Immune system attack

Your dog’s bone marrow contains “baby” cells that make up the complex immune system of the canine. Parvovirus makes its way to the bone marrow and attacks these cells.

This is also to the virus’s advantage, as it shuts down the dog’s (the “host’s”) defenses at its source, and drops the white blood cell count to a very low level.

Intestinal signs

The cells that line a dog’s intestines are in charge of absorbing nutrients from digested food. They also provide a barrier between the dog’s body and any bad stuff that may be in the digested material from the “outside world.”

When faced with parvo, these cells turn over very quickly, and are prime targets for parvovirus. Once the cells are infected, the barrier breaks down, reducing nutrient absorption and allowing more access to the body for bacteria.

The intestinal form usually brings on heavy vomiting in dogs, sudden weight loss, diarrhea, and loss of appetite.

Parvo normally shows up in the intestinal form, and will affect dog’s ability to absorb nutrients from food. The dog will become dehydrated and weak very quickly, and you may notice the wet tissue around the eyes and mouth becoming red. Their heart may also start beating unusually quickly. Low body temperature and abdominal pain are also signs of Parvo.

Cardiac infection

Parvo can also affect the dog’s heart.

The cardiac form caused by parvovirus is less common, but it attacks the heart muscles of young puppies, usually those between 6 weeks and 6 months old, and typically leads to death.

How is parvo in dogs treated?

Parvo in Dogs - What You Need to Know About Canine ParvovirusThe sooner your dog is treated for parvovirus, the better the prognosis for your canine’s survival.

Parvo in dogs is very treatable but treatment must be initiated quickly and aggressively. This treatment requires hospitalization, and the dog is isolated from other animals to prevent spreading the infection. The course of treatment can last from a few days to a couple of weeks, depending on the case, and can be very expensive.

The goals of parvo treatment are to provide supportive care in maintaining hydration, keeping the dog comfortable, and preventing secondary bacterial infections.

Treatments of canine parvovirus include antibiotics, antiemetics (medication for nausea), intravenous fluids, gastroprotectants (antacids), anthelmintics (a drug that fights parasites) and Tamiflu® (Oseltamivir), to name a few most common ones. Some dogs may require plasma or whole blood transfusions. Nutritional support is also paramount to keep the dog’s energy levels up.

With hospitalization and aggressive care, the survival rate of dogs with parvo is about 80 percent.

Death usually occurs from severe dehydration, bacterial toxins in the blood, a secondary bacterial infection, or intestinal hemorrhaging. Since puppies have a less developed immune system, their prognosis is much lower than that of adult dogs. Sometimes puppies suffer shock and die suddenly after being infected with the disease.

Potential new and cheap treatments for canine parvovirus are currently in the works, according to Colorado State University.

How to keep your dog safe from parvo

Parvovirus in dogs is not something to be taken lightly. It is a devastating illness that progresses quickly, and can be fatal.

It is impossible to completely shield your new puppy from Canine Parvovirus, because it is everywhere [6, 7]. However, you can take a few simple measures to reduce their exposure to parvo:

  1. Don’t frequent high dog-traffic areas, such as pet stores and dog parks
  2. Only socialize with fully-vaccinated adult dogs
  3. Keep access to the outdoors to a minimum
  4. Eliminate access to feces or waste from other animals

During his first weeks, your puppy will be developing immunity to parvo through vaccinations, and through the strength of its growing immune system.

Vaccination is highly effective against parvovirus [8]. Puppies begin their vaccination series for parvo around 8-9 weeks of age, and every 3 weeks after that until they are about 16-20 weeks old [9].

Below is a sample vaccination schedule:

  • 9 weeks of age – First parvovirus vaccination
  • 12 weeks of age—Second parvovirus vaccination
  • 15 weeks of age—Third parvovirus vaccination

If your puppy started the parvo vaccination series before 8 weeks of age, he should have a fourth vaccine around 15-16 weeks of age. This is because lingering antibodies from the Mother can keep the vaccine from working properly.

Some dog breeds are more likely to contract parvovirus than others. These include Rottweilers and Pit Bull terriers among others [10]. These puppies should receive one more vaccination, up to 20 weeks of age.

Once your puppy is 1 year of age, a vaccine can be given that will last for 3 years. This vaccine should be repeated on-time, every 3 years for life.

What about puppy play dates?

The “Golden Opportunity” for puppies to be the most successfully socialized with other dogs is before 16 weeks of age. This also happens to be the period when puppies are most vulnerable to diseases like parvo [9]. So, what do you do?

Socialize them! That’s right. If your puppy has one or two vaccinations “on board”, it is OK to go ahead and socialize them. Remember to keep their exposure to a minimum as previously mentioned, and also:

  • Join a “puppy kindergarten” class
  • Socialize with adult dogs that you know are fully vaccinated
  • Keep up with your puppy’s vaccination schedule

For more information, please check out the American Veterinary Society of Animal Behavior’s Position Statement: Puppy Socialization and Vaccination (PDF)

The bottom line on parvo in dogs

If you notice any of the symptoms mentioned above, whatever the age of your dog, contact your vet immediately.

With proper care early in the virus’s development, parvo in dogs can be treated and beaten. With increased knowledge and vigilance among dog owners, Canine Parvovirus is being seen less and less in most veterinary clinics. More research is done to treat parvo in dogs, and the future looks better for our loyal companions [11].

There’s no point stressing about this, however. With a little bit of knowledge, proper vaccination, sufficient attention and preparation, your puppy will be safe from parvovirus.

[toggle title=”References“]
  1. Decaro N, et al. Occurrence of severe gastroenteritis in pups after canine parvovirus vaccine administration: a clinical and laboratory diagnostic dilemma. Vaccine. 2007 Jan 26;25(7):1161-6. Epub 2006 Oct 25.
  2. S. Nandi and Manoj Kumar. Canine Parvovirus: Current Perspective. Indian J Virol. 2010 Jun; 21(1): 31–44. Published online 2010 Sep 3. doi: 10.1007/s13337-010-0007-y
  3. Charles Hong, et al. Occurrence of Canine Parvovirus Type 2c in the United States. J Vet Diagn Invest. 2007 Sep;19(5):535-9.
  4. Mech LD, et al. Demographic effects of canine parvovirus on a free-ranging wolf population over 30 years. J Wildl Dis. 2008 Oct;44(4):824-36.
  5. Felsburg PJ. Overview of immune system development in the dog: comparison with humans. Hum Exp Toxicol. 2002 Sep-Oct;21(9-10):487-92.
  6. Yufei Geng, et al. Co-Circulation of the Rare CPV-2c with Unique Gln370Arg Substitution, New CPV-2b with Unique Thr440Ala Substitution, and New CPV-2a with High Prevalence and Variation in Heilongjiang Province, Northeast China. PLoS One. 2015; 10(9): e0137288. Published online 2015 Sep 8. doi: 10.1371/journal.pone.0137288
  7. Sanjay Kapil, et al. Canine Parvovirus Types 2c and 2b Circulating in North American Dogs in 2006 and 2007. J Clin Microbiol. 2007 Dec; 45(12): 4044–4047. Published online 2007 Oct 10. doi: 10.1128/JCM.01300-07
  8. Waner T, et al. Assessment of maternal antibody decay and response to canine parvovirus vaccination using a clinic-based enzyme-linked immunosorbent assay. J Vet Diagn Invest. 1996 Oct;8(4):427-32.
  9. De Cramer KG, et al. Efficacy of vaccination at 4 and 6 weeks in the control of canine parvovirus. Vet Microbiol. 2011 Apr 21;149(1-2):126-32. doi: 10.1016/j.vetmic.2010.11.004. Epub 2010 Nov 9.
  10. Houston DM, et al. Risk factors associated with parvovirus enteritis in dogs: 283 cases (1982-1991). J Am Vet Med Assoc. 1996 Feb 15;208(4):542-6.
  11. Decaro N, et al. Canine parvovirus–a review of epidemiological and diagnostic aspects, with emphasis on type 2c. Vet Microbiol. 2012 Feb 24;155(1):1-12. doi: 10.1016/j.vetmic.2011.09.007. Epub 2011 Sep 12.

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