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At what age does parvo not affect dogs?

Parvo in Dogs

There is good news and bad news about Parvo. Canine Parvovirus Type 2 (CPV) is a highly-contagious incurable viral illness and, sadly, the bad news is that around nine in ten puppies that contract it and do not receive prompt treatment will die.

The good news is that 85% of infected puppies who are treated go on to survive although treatment can be drawn-out and distressing.

The even better news is that parvovirus in dogs can be virtually eliminated by a simple vaccine given every two to four weeks until 16 weeks of age. Is it really worth the risk not to vaccinate?

There most common form of parvo dog disease hits the intestine and is characterised by vomiting, diarrhoea, lethargy, weight loss, and lack of appetite. Much rarer is cardiac parvovirus, which attacks the heart muscles of very young puppies, often leading to death. It’s usually found in puppies under six weeks old who contracted from their mothers in the womb. It can be difficult to spot, and often the only indication is the death of the puppy. If they survive the infection, signs of long term cardiac damage may not surface for several years, but its victims can later suffer from congestive heart failure.

With intestinal Parvo, it is not the virus itself which kills the patient, but the effects of dehydration and secondary infection.

Dogs of any age can be affected, but most acute cases of Parvo are seen in puppies aged between six weeks and six months simply because they have less developed immune systems.

The scary thing is that your cherished puppy could become infected by simply being walked through your local park or even down the street where you live. It is spread by direct – or indirect – contact with dog faeces. High concentrations of the virus are found in the stool of infected animals, so it only takes a sniff to contract parvo, but even soil on a shoe is all that is needed. This is because Parvovirus can live in the ground for several months, so dogs can still be infected even if the stool is no longer present.

Within two days of the virus entering your dog’s body, it moves to the lymphoid tissues, where it can then enter the bloodstream and move to the digestive system and bone marrow. This results in visible symptoms within 7 to 10 days.

Certain dog breeds seem more prone to CPV infection including Rottweilers Doberman Pinschers, Pit Bulls, Labrador Retrievers, German Shepherds, English Springer Spaniels and Alaskan sled dogs.

Since CPV is a viral infection and so cannot be cured, treatment is focused the symptoms and preventing secondary bacterial infections, which is why the best thing to do prevent it in the first place with proper vaccination.

Puppies get some natural protection from antibodies passed on by their mothers but should be vaccinated at six, nine and 12 weeks, and should be kept away from strange dogs until at least two weeks after the final jab. If your dog is one of the at-risk breeds, he will need jabs for up to 22 weeks.

What are common parvo symptoms?


Since the most common form of CPV is the intestinal form known as enteritis, parvo symptoms include often severe vomiting, diarrhoea, dehydration, dark or bloody stool, and in severe cases, fever. Blood tests may also reveal lowered white blood cell counts.

While most cases are seen in puppies younger than 12 weeks old, parvovirus enteritis can be seen in dogs of any breed, sex, or age. Death can occur a matter of hours after the end of the incubation period which can be between 4 to 14 days, so it is vital to spot parvo symptoms in dogs as soon as possible and seek your vet’s assistance.

Bloody diarrhoea – with or without vomiting – are not necessarily signs of parvo and so if you present your dog at the vets, expect them to carry out diagnostic CPV tests to rule out other causes. A full physical exam and further lab tests can determine the severity of the disease.

How is parvovirus disease treated?

As an incurable viral infection treatment is directed at supportive therapies. Because severe dehydration is the real killer, replacing lost fluids is probably the single most important treatment, usually by intravenous electrolyte solution. However, in milder cases, subcutaneous or oral fluids may be used for several days.

At the other end of the spectrum, really severe cases may require treatment with blood transfusions, and in almost all cases, antibiotics are used to help control secondary bacterial infections.

CPV was first observed in the Seventies and within two years of its discovery it had spread worldwide. Today it ranks among the most infection diseases among canines. Without intervention it can kill its victims within a few hours or a few days depending on the strain and the strength of the animal: smaller breeds have a lower survival rate and so you should react quicker at the first signs of severe vomiting and/or bloody stool.

Parvo itself does not directly cause pain but the symptoms can be distressing and uncomfortable. Your vet will administer pain relief if required while treatment progresses.

Indeed, if your pet ever shows sign of pain for any cause consult your vet immediately. It may be a visible sign of something seriously wrong. While dogs who survive Parvo generally go on to lead long and happy lives, cell death in the intestines and bone marrow of a puppy can stunt their growth, although it may be hard to tell if the eventual size is unknown, but it can also cause long-term kidney or liver damage and permanently weaken the immune system, leaving him more susceptible to other diseases in later life.

If your dog has survived parvo – and the prospects are good – be aware that he will still have the virus in his faeces for up to three weeks, so for the sake of other puppies out there be extra careful to remove the offending poos and dispose of them safely.

And as Parvo survivors become carriers of the virus they will continue to sporadically poop out the virus at various points for the rest of their lives. Bag it and bin it.

Preventing Parvovirus


All sickness is difficult for these little friends, but parvovirus is horrible, causing bloody, watery diarrhea. It’s extremely contagious, very expensive to treat, and, most important, parvovirus is preventable if puppies, their moms, and other dogs get the parvovirus vaccine.

Every dog parent should vaccinate their pups to keep them safe. If not, they need to know what parvo can do to their pups and be taught how to prevent the spread to other pups in the house.

What Is Parvovirus?

The Merck Manual of Veterinary Medicine calls canine parvovirus a “highly contagious and relatively common cause of acute, infectious GI illness in young and/or unvaccinated dogs.” This means that parvo can cause your pup to get sick suddenly.

It is just one of a large family of viruses that affect many animals and is a significant cause of death in young dogs.

Which Dogs Are Most Susceptible to Parvo?

Puppies ages 6 weeks to 6 months are the most likely to get parvo. Vaccinated moms pass on protective antibodies through nursing their puppies. That’s why it’s important for all dogs to be vaccinated against parvo. Older puppies are in danger of getting parvo until they receive a full set of vaccinations before they turn three months old.

The American Kennel Club reports that, for reasons that aren’t entirely clear, certain breeds are more likely to contract parvo, such as:

  • Rottweilers
  • Doberman Pinschers
  • American Staffordshire Terriers
  • English Springer Spaniels
  • German Shepherd Dogs
  • Labrador Retrievers

Signs of Parvovirus

As a veterinarian, I can tell you the most unforgettable sign of parvo is the large volume of smelly and usually bloody diarrhea. It haunts me, especially knowing that it doesn’t need to be that way — if all pups were vaccinated.

Other symptoms of parvovirus can include the following:

  • Vomiting
  • Fever (or too low of a temperature)
  • Lethargy (listlessness)
  • Anorexia (they don’t want to eat)
  • Weight loss
  • Weakness
  • Dehydration
  • Depression

What to Do if You Suspect Parvo

Contact your vet immediately. You don’t want to mess with parvo. The sooner you bring your pup in to see your veterinarian the better. When you call to make the appointment, they’ll need to know your pup has diarrhea and that you hope it’s not parvo so they can take measures to prevent the spread in the clinic to their other patients.

You’ll also want to do everything you can to keep other animals away from your puppy’s vomit and poop because that is how parvo spreads.

Unfortunately, animals begin shedding the virus within 4 or 5 days of exposure, often before showing symptoms. That’s why it’s even more important to take measures to prevent parvovirus from infecting dogs in the first place.

What’s troubling is that veterinarians are reporting a spike in the number of cases of parvo during the COVID‑19 pandemic. Skipping vaccinations is probably the cause.

How Does Parvo Spread?

Puppies are exposed to parvo in two ways:

  1. Direct exposure—sniffing, licking, or eating poop or vomit that contains the virus
  2. Indirect exposure — coming into contact with virus particles that are on things like food or water bowls, collars, and leashes, or even on people who handled infected dogs

This nasty virus can survive for up to a month indoors, and outdoors it can survive for up to a year! It must be cleaned up the right way. Not every cleaner kills parvovirus. Your veterinary team will know how to guide you through this process.

The Morris Animal Foundation , which does important work to fund research to help animals, recommends the following actions to prevent exposure:

  • Keep young dogs isolated until they finish their puppy vaccinations (no dog parks)
  • Keep puppies in clean environments
  • Make sure that all puppies and adult dogs are vaccinated

Because mothers pass along protective antibodies in their milk, it’s especially important that any female used for breeding is vaccinated.

Parvovirus Vaccines

I can’t emphasize enough how important it is to give puppies a full course of parvovirus vaccines. Compared to treating parvo, the vaccines are inexpensive, and they are highly effective. Canine parvovirus vaccines have saved millions of lives.

The single best and cheapest way to prevent parvo is to vaccinate your dogs and puppies. Every single one of them. If you’re thinking of breeding your dogs or if they haven’t been “fixed,” make sure that you get them vaccinated. Otherwise, you risk having sick dogs, and the cleanup will not be pleasant or easy.

This is another reason to get your pups from reputable rescue organizations, shelters, or breeders that can provide proof of veterinary care with all the core vaccines. Some will offer a free veterinary visit to double‑check that your new pup is healthy. Be aware that the veterinarian will need to see any veterinary records you do have and might need to charge for any additional services needed to check out your new pup.

Your veterinarian knows when puppies or dogs need each kind of vaccine, starting as young as 6 weeks of age, so vaccinate your pups when your veterinarian tells you it is needed. If you suspect your dog is pregnant, start saving up for the vaccines and dewormings that all her puppies will need to be healthy and happy in your home.

Diagnosing and Treating Parvo

Veterinarians often recognize the telltale signs of parvo right away: smelly, bloody diarrhea, vomiting, and lethargy in a puppy that should be bounding around exploring and enjoying its new world. Since there are other things that can cause these signs, it’s best if your veterinarian can test their poop for the virus and their blood to know just how sick your pup is. If you are on a tight budget, you’re better off asking your vet to treat your pup’s symptoms and asking how to clean your home and yard to prevent the virus from spreading to other pups.

Parvovirus Treatment

There is no cure for parvovirus, but the disease can be treated if caught early. Untreated puppies only survive 9% of the time, while up to 90% of the puppies treated in vet hospitals survive parvo.

Treatment is expensive, and infected pups are not happy. Not to mention the mess they make in and around the house with vomiting and diarrhea.

Most treatment involves providing fluids to prevent dehydration and supporting pups while their immune system fights the virus. Sometimes an infected pup will need antibiotics and a feeding tube. Scientists are looking for other treatment options for infected pups.

The first few days are critical. The AKC says that most puppies (68‑92%) that are treated by a veterinarian do recover — if they survive the first 3‑4 days. The Morris Animal Foundation says that if finances are a concern, ask your veterinarian to provide initial treatment at the clinic and ask them to show you how to treat your pup at home and keep others safe. This involves learning how to give fluids under the skin, cleaning your home, and keeping your pup away from other puppies and dogs. It may also mean giving your pup medications. This can still be quite expensive and can take more effort than you can give. In these cases, have an honest conversation about whether euthanasia might be the best solution under the circumstances.

Some studies show that parvovirus survivors might have more stomach and intestinal problems later in life.

A Parvo‑Free World

I look forward to a time when I never hear about another adorable pup suffering from the symptoms of canine parvovirus.

If everyone keeps their puppies up to date on vaccinations, strives to keep young dogs in clean homes, and supports efforts to vaccinate dogs, this future is possible.

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