The pandemic has taught us many things … from how to “Zoom” to how little many Americans understand science, especially the concept of herd immunity.
Now, I know you may not like to think of yourself as part of a herd, but you are, at least in terms of infectious diseases. Herd immunity is defined as the condition in which a specific population has greater resistance to the spread of a contagious illness because a high percentage of the individuals have pre-existing immunity, either through vaccination or previous infection. Ok, wake up! I promise we’re going to talk about pets, not just pandemics.
I was thinking today how lucky I am to practice in an area where we almost never see dogs infected with canine distemper virus or parvovirus. And how lucky I am to practice in an area where most pet owners willingly follow their veterinarians’ advice about vaccination. Unfortunately, the down side of rarely seeing these dangerous and often deadly diseases is that owners may not know much about them, or may get complacent about preventive vaccination.
Let’s start with canine distemper virus (CPD). First misconception — CPD has nothing to do with a dog’s temperament. It is a highly contagious virus in the same genus as that which causes measles in people. (Measles is another disease where vaccination for human herd immunity has been essential in reducing the incidence, and where vaccine hesitancy has resulted in new outbreaks in the U.S.) Canine distemper virus infections have been reported in a wide variety of animals, including cat, dog, jackal, coyote, hyena, lion, tiger, leopard, ferret, fox, weasel, raccoon, seal, sea lion, dolphin, and giant panda. There is no evidence that CPD is contagious to people, but because it has been known to infect some primates, and because it is related to measles, epidemiologists keep a watchful eye.
In dogs, mild cases may be no worse than a cold with fever, cough, runny nose, and red eyes, or a minor stomach bug with vomiting and diarrhea. Severe cases may have extreme vomiting and diarrhea, pneumonia, blindness, and/or neurological symptoms such as incoordination and seizures. There is no specific cure for canine distemper virus. All veterinarians can do is provide supportive care. Young dogs are most susceptible, and mortality rates can be as high as 50 percent.
Canine parvovirus (CPV) is another disease that primarily affects young dogs, though unvaccinated dogs of any age are susceptible. There appears to be an increased risk for certain breeds including Rottweilers, Dobermans, Labs, American Staffordshire terriers, and Arctic sled dogs. It poses no risk to humans, but other canids, such as wolves, coyotes, and foxes, are susceptible. Exposure is through contact with respiratory secretions and/or feces of infected dogs. The virus is very hardy and can persist in the environment long after the carrier dog has left.
Once infected, a pup will get sick within one to two weeks, with lethargy, depression, fever, vomiting, severe bloody diarrhea, and pain. This can rapidly progress to severe dehydration, sepsis, blood clots, heart failure, shock, and death.
I was in veterinary school in Philadelphia when canine parvovirus first emerged. It was a heartbreaking time. We had no vaccines. We had no way to treat it other than supportive care. We were in a major city with many, many dogs and many, many parks that we would call “fecal fields,” so the disease spread like wildfire. The school set up an isolation “parvo ward.” We had to wear full isolation gear. Booties, gowns, caps, and masks. The cages were filled with dying puppies. The smell was … Ok, I will stop here. All I can say is that one day in a puppy parvo ward will make anyone a lifelong advocate for vaccination.
As far as treatment goes, remember people getting monoclonal antibody treatment for COVID-19 infections? Well, there is a canine parvovirus monoclonal antibody treatment now available that can be given to pups after exposure, or after testing positive for CPV. It appears to be well-tolerated and effective in reducing clinical signs, but treatment for CPV, like for CDV, is still primarily supportive care. Intravenous fluids, control of secondary bacterial infection, pain relief, antivomiting drugs, and nutritional support. When I was in that dreadful parvo ward in the late 1970’s, most of our patients died. Nowadays, with five to seven days of hospitalization and intensive (and expensive) therapy, 75 percent survive.
For canine distemper, vaccines became commonplace in the late 1950s, but in areas where vaccination rates are low, dogs still get infected, still shed and spread the disease, still die from it. The same is true for canine parvovirus. In the early days, we actually gave dogs the feline panleukopenia vaccine to try to protect them, as the viruses are similar. A true canine parvovirus vaccine was developed soon after, and quickly became part of our core vaccination protocol.
Herd immunity: Your dog needs a series of vaccines to protect him through puppyhood as the maternal antibodies he may have gotten from his mother wane, and his own immune system matures. The American Animal Hospital Association Guidelines advise puppies receive a series of at least three distemper-parvo combination vaccines between 6 and 16 weeks of age, at two- to four-week intervals. Certain breeds or high-risk individual dogs may get boosters up to 20 weeks old. Unvaccinated adult dogs should get a series of two injections. After that, all dogs should get a booster one year later, then every three years.
If you have “vaccine hesitancy,” talk to your veterinarian. There are a few legitimate circumstances where we do not advise vaccinating an individual dog, but these are rare. Don’t leave your pup unprotected. Pets travel to the Vineyard from all over the country, even from abroad, and bring diseases with them. Don’t be that person with magical thinking who believes the Island is somehow immune. (We all know how that went with COVID-19.) Contribute to herd immunity. Keep your pets healthy. Get them vaccinated.
