When it comes to the health and well-being of our pets, understanding the risks of infectious diseases is crucial to ensure our animals remain healthy and well. One valid concern for pet owners who share their homes with both dogs and cats is cross-species transmission, where a pathogen capable of infecting one species manages to jump to another species and establish infection.
What is canine parvovirus?
Canine parvovirus type 2 (CPV-2) is a highly contagious viral infection that emerged in 1978 and affects members of the Canidae family, which includes dogs, wolves, foxes and coyotes. This highly infectious viral infection causes severe gastrointestinal symptoms, including vomiting, hemorrhagic diarrhea, leukopenia (low white blood cell count) and immunosuppression.
The virus primarily targets rapidly dividing cells, which are commonly found in the gastrointestinal tract, lymphoid tissues and bone marrow.
- In the gastrointestinal tract, the virus attacks the lining of the intestines, particularly the crypts of Lieberkühn, where the cells responsible for nutrient absorption are located. Affected dogs develop severe inflammation, ulceration and cell death, causing gastrointestinal symptoms that include vomiting, hemorrhagic diarrhea, as well as an inability to absorb nutrients.
- Parvovirus suppresses the immune system by infecting and destroying young immune cells in the bone marrow and lymphoid tissues responsible for producing white blood cells (neutrophils and lymphocytes), which defend against infection. This makes the dog more vulnerable to secondary infections.
- Prolonged vomiting and diarrhea lead to dehydration and electrolyte derangements which can impact the ability of liver and kidneys to function.
- Damage to the intestinal lining causes bacteria and endotoxins to be released from the gut into the bloodstream causing systemic inflammation, septicemia and endotoxemia.
Untreated parvovirus is almost always fatal and requires prompt and aggressive fluid therapy, antibiotics and supportive care. Unvaccinated puppies under six months are most at risk.
Can cats catch parvovirus from dogs?
Cats cannot catch parvovirus from dogs. Most viruses are adapted to infect specific hosts, and the way they interact with their host cells determines their host range. The differences in cellular receptors and immune responses between cats and dogs, as well as the genetic makeup of the viruses, limit cross-species infections. Canine parvovirus and feline panleukopenia virus exhibit host specificity, which means they are adapted to infect dogs or cats, and cannot effectively infect the other species. This is because viruses bind to specific cellular receptors to enter host cells. Canine parvovirus and feline panleukopenia virus have evolved to bind to receptors present in their respective host species.
Cellular receptors and viruses are similar to a lock-and-key mechanism. Receptors on the surface of host cells act as the lock, and the virus acts as the key. The cellular receptor is a protein or molecule present on the surface of the host cell. The virus has a specific structure on its surface, often a protein or glycoprotein, that can interact with the cellular receptor. Just like a lock can only be opened by a key that fits its specific pattern, a virus can only infect a host cell if its surface structure is compatible with the cellular receptor.
The bad news is cats can catch feline panleukopenia virus (also known as feline distemper or feline parvovirus). Feline panleukopenia and canine parvovirus are both members of the Parvoviridaw family but have different host species. Both viruses cause severe gastrointestinal dysfunction, weaken the immune system and are life-threatening if not treated promptly.
Where did canine parvovirus come from?
Interestingly, the most widely accepted theory is that CPV-2 canine parvovirus (CPV) originated from a mutation of the feline panleukopenia virus (FPV) or a closely related virus, which allowed the virus to jump species from cats to dogs. This hypothesis is based on the close genetic similarity between CPV and FPV and the fact that the first CPV isolates could infect cats as well as dogs. It’s believed that a few key mutations allowed the virus to jump species from cats to dogs. Over time, further evolution led to new variants (CPV-2a, CPV-2b, and CPV-2c), which show a preference for infecting dogs.
How do cats and dogs catch parvovirus and feline panleukopenia?
- Fecal-oral/urine-oral: The most common route of infection is the oral/nasal route. The virus is present in feces, urine or saliva and can survive in the environment for a long time.
- Fomites: Contact with bedding, food bowls, cages, grooming equipment, and even by a person who has been in contact with an infected cat via the hands or clothes or tracking the virus into the home on their shoes.
- Vertical: The virus is passed from the mother to her unborn kittens or puppies.
Symptoms of canine parvovirus and feline panleukopenia
The incubation period can range from 2 – 14 days, but symptoms usually occur within around a week of exposure. When symptoms do present, the onset is rapid.
- Lethargy: Animals infected with parvovirus often become extremely lethargic due to dehydration and the body’s overall response to the virus.
- Loss of appetite: Infected animals lose their appetite, due to nausea.
- Vomiting: This is a common symptom and can lead to severe dehydration.
- Hemorrhagic diarrhea: Infected animals often have severe, bloody diarrhea, which can also lead to dehydration and electrolyte imbalances.
- Fever: A high fever is common as the animal’s body tries to fight off the infection.
Cats and dogs may hang off their food or water bowl, have a hunched appearance and the coat looks unkempt. Dehydration causes the skin to lose its elasticity and the eyes appear sunken.
Both canine parvovirus and feline panleukopenia are devastating diseases with a high mortality rate in kittens and puppies. Treatment aims at offering support while the body fights the infection. This will include aggressive fluid therapy, medication to control vomiting and antibiotics if a secondary infection is present.
Young kittens and puppies are at the greatest risk due to their immature immune system.
The virus is shed in the feces for several days to six weeks in the feces up to six weeks after recovery. Parvoviruses are extremely hardy and can be transported a great distance via fomites (footwear, clothing etc).
After a canine parvovirus outbreak, it’s crucial to follow appropriate husbandry practices to ensure the environment is properly disinfected and to prevent the virus from spreading further.
- Isolate any infected animals to prevent the spread of the virus. This includes avoiding shared food and water bowls, toys, or bedding.
- Clean all surfaces, objects, and areas the infected animal has come into contact with. Parvovirus is resistant to many common household cleaners. A 1:32 bleach dilution is effective against parvovirus, but it is important to clean all areas prior to bleaching as organic matter deactivates bleach.
- Dispose of any feces or vomit from the infected animal immediately and disinfect the area.
- Make sure all other pets in the house are up to date with their vaccinations.
Reducing the risk
Canine parvovirus and feline panleukopenia are both deadly, especially to kittens and puppies. The virus is shed in feces and can remain in the environment for up to a year at room temperature.
The only way to reduce the risk of parvovirus and feline panleukopenia virus is with vaccinations, which are both safe and effective. Puppies and kittens receive three vaccinations spread 4 weeks apart. After the initial set of three vaccines, puppies and kittens will receive an ongoing booster vaccination once a year.
Vaccinations stimulate the body’s immune system to protect against a number of harmful pathogens. They work by introducing a less harmful, inactivated or weakened virus to the body which stimulates the immune system to produce antibodies. If the cat or dog encounters the actual disease in future, the immune system is prepared to fight it off more effectively, reducing the chance of severe illness.
Keep puppies and kittens away from public areas until they have had all of their vaccinations.