Canine parvovirus is a contagious virus infection that mainly affects puppies. It produces gastrointestinal (and sometimes cardiac) problems and can be lethal, especially for puppies. The canine parvovirus (CPV) is highly infectious and your dog doesn’t even have to meet an infected dog to catch it since it can spread via faeces. The canine parvovirus occurs all over the world.

The canine parvovirus wasn’t recognized until 1978, and the disease seems to have appeared in the 1970s. If the virus actually developed then or if there is some other reason why it wasn’t recognized until then is yet not known. What we do know is that by 1980 it had been found all over the world. It might be a mutated feline distemper parvovirus, but the experts still do not know for sure.  The canine parvovirus is very similar to the feline distemper parvovirus; the only difference is two amino acids found in the capsid protein VP2. The canine parvovirus can also be mutated form of some other less known parvovirus, perhaps the feline parvovirus (FPV) or a parvovirus found in wild mammals.

There exist several identified strains of canine parvovirus, including CPV2a, CPV2b and CPV2c (a Glu-426 mutant). If your dog gets a normal routine test it will normally not be possible to tell exactly which strain that has infected your dog.

CPV infections in dogs

 
CPV comes in two forms; the intestinal form and the cardiac form. The cardiac form is rare in countries where vaccination of breeding dogs is common, since it develops in puppies that receive the parvovirus in uterus or shortly after being born. Cardiac CPV can lead to sudden heart failure; usually before the puppy reaches an age of eight weeks. The heart failure is caused by parvovirus attacking and destroying the heart muscle.

The intestinal form of canine parvovirus enters the dog via its mouth, e.g. through faeces, infected soil or shared toys. It will then infest the lymphoid tissue in the throat, where it multiplies before spreading to the bloodstream. The canine parvovirus is known to attack cells that divide them selves rapidly in the dog, such as the cells found in bone marrow, lymph nodes and intestinal crypts. This weakens the immune system of the dog and can make it possible for bacteria that normally inhabit the intestines to enter the bloodstream where they cause sepsis. An infected dog can release parvovirus through its faeces for up to 3-4 weeks after being infected. Some dogs become asymptomatic carriers that regularly spread the virus without showing any signs of illness.  

CPV vaccination for dogs

Really young puppies can be protected by antibodies from their mother, especially if they nurse. Unfortunately, the effects of these antibodies often wear off before the immune system of the puppy is capable of handling the canine parvovirus. Most veterinarians recommended giving puppies a long series of vaccine shots, from the time that the anti-bodies from the mother starts to wear off to a point in time when the effect of these anti-bodies are definitely gone.

Canine parvovirus and certain breeds

Some breeds seem to be more inclined to CPV than others. Examples of such breeds are the Labrador Retriever, Rottweilers, Pit bull terriers, and Doberman Pinschers. 

CPV treatment and medicine

The exact treatment will depend on how early the disease is diagnosed, and which type of CPV your dog develops. In sever cases, hospitalization can be necessary. In milder cases, home treatment with IV fluids and colloids can be enough. IV fluids are often combined with antibiotic injections, e.g. cefoxitin, timentin, metronidazole, or enrofloxacin. Anti-nausea injections (antiemetics) can also be necessary, e.g. metoclopramide, ondansetron, dolasteron, or prochlorpromazine. Severe protein loss in dogs can be treated with fresh frozen plasma and transfusions of albumin from a human.  A transfusion of blood plasma from a donor dog that has successfully combated CPV in the past can give passive immunity. If you cannot find a suitable dog, you can purchase frozen serum. Anecdotal evidence indicates that oseltamivir (Tamiflu) might be able to limit the ability of the canine parvovirus to invade the crypt cells of the dog, but this has not been confirmed.

Vaccinating dogs against canine parvovirus is extremely important!

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