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It's Not just a shot . . . understanding your pets' vaccines

Grizzle and white dog on lead, Noah's blue backdrop
Happy dog, ready to go play!

As springtime approaches across most of our viewing area and the temperatures increase, both people and pets will be spending more time outside. While fresh air and sunshine are great mood enhancers and important for our well-being, it is important to note that dangers lurk for pets who have not been properly vaccinated!! Deadly, highly contagious diseases, such as canine parvovirus, canine distemper, and feline panleukopenia are common in the environment and pose risks, especially for new puppies and kittens.

People routinely ask veterinary teams about the “shots” that their particular pet’s needs. Diving into the various vaccines that are available to protect our four-legged friends is far too much for just one blog, so we will break this up into multiple installments, reviewing the different vaccines, understanding how they work to safeguard our pets, and, finally, handling those concerns and urban myths about vaccination.

So . . . let’s jump right in and learn a little IMMUNOLOGY!

As all animals go through life, they will encounter things that are foreign to them. It could be pollen from local plants inhaled into their lungs, parasites that they pick up from forays outside, or even microbes, like viruses and bacteria, that have the potential to cause disease. Our bodies are well designed to help fight off these invaders through a tough exterior barrier (our skin), generalized cells that patrol our bodies looking to gobble up these invaders (the technical term is phagocytosis), and an adaptive immune system that can learn and eliminate those foreign entities.

Brindle and white pit bull on red chair
When is this lecture gonna be over??

Vaccinations take advantage of this well-oiled process by using viruses and bacteria that have been altered to NOT cause significant disease, but still prime the immune system so that it will recognize the wild-type, or disease-causing organisms. In some cases, only bits and pieces of the germ might be used and in others, such as rabies vaccines, the virus has been “killed” by inactivating it with formaldehyde or heat. Once our immune systems “sees” and recognizes these disease causing organisms, it can generate a rapid response to help protect the body. In short, our bodies are constantly battling against almost invisible enemies who use sneak attacks, hide within our own cells, or change their appearance in order to wreak havoc. If we can marshal enough antibodies and immune response cells to beat them back, we will win this war . . . but if the viruses or bacteria can get a foothold and multiply faster than our ability to stop them, that’s when disease strikes!

Electron microscopy of canine parvovirus
Canine parvovirus particles seen by electron microscope

For our pets, it is vitally important to protect them from serious and life-threatening diseases. For example, canine parvovirus (CPV) is very common in the environment, so your dog is exposed anytime he or she leaves your home and yard. What makes matters worse is that this tough little virus can remain active in the environment for 1-2 years! We can even be unwilling transportation for the virus if our shoes come into contact with it while walking the neighborhood, hiking, or visiting places where other dogs have been.

Canine parvovirus likes rapidly dividing cells, so it will preferentially look to infect the gut (transmission is via the fecal -oral route) where the crypt cells of the dog’s intestine are constantly dividing and replacing themselves. Additionally, CPV will make its way to the bone marrow, where it infects and kills the cells responsible for producing certain white blood cells. Clinically, what we see is a pup with profuse, bloody diarrhea (from the loss of the intestinal cells), unchecked bacterial infection throughout the body (from the lack of white blood cells to fight it off), and a pup vomiting because he/she feels REALLY crappy! Puppies die from dehydration and overwhelming sepsis (bacterial infection). Treatment for this terrible disease consists of hospitalization with IV fluids to replace losses, IV antibiotics to fight off the bacterial infections, and a lot of “TLC”. Even with optimal treatment, multiple days in the hospital, plasma transfusions, etc, about 1 pup in 10 will still die from this disease. When optimal treatment is not available for whatever reason, the mortality rate climbs steeply, often reaching 80-90% in puppies.

Similarly, feline panleukopenia can affect our kittens. In fact, most veterinary scientists believe that the canine parvovirus type 2 (what I have described above) actually is a direct descendant via mutation of the feline panleukopenia virus…that is, they both belong to the family, Parvoviridae. Like canine parvovirus, feline panleukopenia is deadly to unvaccinated cats and kittens.

The good news in all of this is that we have safe and effective vaccines for both of these diseases! Puppies and kittens should receive 3-4 booster vaccinations starting at about 6-8 weeks of age and then given every 3-4 weeks until they are 16 weeks or older. Some breeds of dogs, especially those with black and tan markings, like Rottweilers, are often encouraged to get additional boosters (up through 20 weeks of age) as these animals seem to have a genetic predisposition for an immune impairment against canine parvo. It’s estimated that Rottweilers are 6 times more likely to contract parvo when exposed compared to other dogs!

Cream Pomeranian in baby stroller
Great day for an outdoor cruise!

Adult boosters should be given at about 1 year of age (both dogs and cats) and then most veterinarians will recommend a 3-year booster schedule after that. While we have strong suspicions that immunity to canine parvovirus or feline panleukopenia lasts longer than 3 years, it’s important to remember that not all dogs respond properly to vaccination, individual pets may respond differently at different points in the lives, and, occasionally, the vaccines are not handled/mixed/stored properly, rendering them inert. The 3-year schedule is a nice compromise between protecting as many dogs and cats as possible while still avoiding “over-vaccination” of our pets. Alternatively, it is possible to check antibody levels in our pets for these diseases (this is called titer testing), but there are controversies surrounding how to interpret these tests and the costs are usually significantly higher than vaccinating. We will discuss this in detail in an upcoming blog.

As you can see, vaccinating our pets is much more than just sticking them with a needle . . . it’s an attempt to create immunization so that we can keep our furry friends safe from diseases that are waiting to pounce! Next time, we will tackle canine distemper as well as rabies.

What’s your biggest concern when it comes to vaccinating your pets?


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