Immunization Awareness Month: Familiarizing with How Vaccines Work

mt. carmel animal hospital How Vaccines Work

Let’s take a look into how vaccines work in detail in honor of immunization awareness month.

To understand how vaccines work, knowing how the body fights illness is essential. When germs invade the body, they attack and multiply. Therefore, this invasion (or infection) is what causes disease. Our immune system uses our white blood cells to fight this invasion. There are many types of white blood cells, but the macrophages, B-lymphocytes, and T-lymphocytes are most involved in fighting off infections. The immune system works off memory after that. Let’s take a look into how vaccines work in detail in honor of immunization awareness month.

How do Vaccines Work?

Vaccines help protect against specific diseases by imitating an infection. This imitation infection helps teach the immune system how to recognize and fight off a potential infection. As a result, the vaccinated body remains with a supply of B-lymphocytes and T-lymphocytes that will remember how to fight the associated disease.

However, it usually takes a couple of weeks for the body to make B-lymphocytes and T-lymphocytes after the vaccination. This means your pet has no protection yet and can still contract the disease we are vaccinating against if they are susceptible within that two-week period.

Side Effects of Vaccines

Because vaccines function by stimulating the immune system, sometimes the vaccine can provoke minor side effects such as fever, lethargy, and soreness at the vaccine site. These symptoms are prevalent and nothing to be concerned about. Rarely, the immune system is on overdrive, causing serious reactions. These include vomiting, diarrhea, and facial swelling, leading to anaphylaxis. These reactions typically happen within an hour of vaccine administration. If your pet experiences any of these symptoms, call us immediately and bring your pet in for treatment.

Vaccine Schedules

Like people, pets also need vaccines. The ideal way to stay on schedule with vaccinations for your pet is to follow your trusted veterinarian’s recommendations. Keep in mind that there are two vaccination categories: core pet vaccines (recommended for every pet) and non-core vaccines (based on your pet’s lifestyle). Talk to us about setting up the best vaccination schedule for your pet, as many vaccines can be given to pets as young as 6 weeks old.


  • Rabies – The 1-year rabies vaccine can be administered in one dose, as early as 3 months of age. This is a core dog vaccine that both Pennsylvania and Maryland laws require. Plus, prevention is key because rabies is 100% deadly to dogs, with no treatment. Once your pet has the vaccination, subsequent vaccines can be done every three years.
  • DAPP – Parainfluenza, and Parvovirus. Distemper and parvovirus are both highly contagious and potentially fatal diseases, which is why this is another core vaccine. At least 3 doses are given to pups between 6 and 16 weeks of age at intervals of every 3-4 weeks. For dogs over 16 weeks, 2 doses are given 3-4 weeks apart. In addition, puppies need a booster 1 year after completing their initial series; all adult dogs require a booster every 3 years.
  • LeptoThis dog vaccination for Leptospirosis is first administered as early as 8 weeks, with a second dose 2-4 weeks later. For dogs over 16 weeks, 2 doses are provided (also 2-4 weeks apart). This vaccine should be given at least once yearly for dogs in high-risk areas. Dogs can contract a leptospirosis infection if they are exposed to rodents and standing water. While this vaccine is non-core, we are in a highly endemic area and recommend it for all dogs.
  • Lyme – This is another non-core vaccine that is highly recommended for dogs in this area because we live in an area with a lot of ticks and a high prevalence of Lyme disease. One dose is administered as early as 9 weeks, with a second dose 2-4 weeks later. In addition, 2 doses (2-4 weeks apart) are administered to adult dogs. Once the initial series is completed, this is an annual vaccine.
  • Bordetella (kennel cough) – Bordetella bronchiectasis is a bacterium that causes the upper respiratory symptoms in dogs commonly referred to as kennel cough. Although it’s usually not a severe condition, Bordetella can be dangerous in young or immunocompromised dogs. This vaccine is given to dogs that are exposed to other dogs at places such as kennels, groomers, training classes, dog parks, etc.
  • Canine Influenza (CIV) – Canine Influenza is a non-core dog vaccine reserved for dogs with high risks of exposure. These dogs typically are around other unknown dogs frequently or are in an area known to have active cases of CIV. In young pups, the first dose is administered as early as 8 weeks; and the second dose is given 2-4 weeks later. Adult dogs would also receive one dose followed by a booster 2-4 weeks later. Subsequent vaccines are given on an annual basis.


  • Rabies – A single dose as early as 8 weeks of age is provided to cats under 16 weeks (revaccinate 1 year later). For an adult cat over 16 weeks, a single dose with a yearly booster is only given. After that, the vaccine can be given every 3 years. As with dogs, Maryland and Pennsylvania laws require this core cat vaccine. Moreover, rabies is 100% deadly to cats with no available treatment. So, prevention is key!
  • Feline Distemper (Panleukopenia) – Panleukopenia is a highly contagious disease that typically affects kittens and can lead to death. This is why this is a core vaccine and is in the combination FVRCP vaccine. This vaccine is given as early as 6 weeks and every 3-4 weeks until the kitten is 16 weeks old. Plus, 2 doses (3-4 weeks apart) are given to adult cats. It is then given annually or every 3 years, depending on your cat’s lifestyle.
  • Calicivirus – Calicivirus is a contagious upper respiratory condition that can produce joint pain, fever, oral ulcerations, and anorexia. This is another portion of the core FVRCP vaccine and is on the same schedule as the Feline Distemper.
  • Feline Herpesvirus – Feline herpesvirus causes feline viral rhinotracheitis (FVR), a contagious upper respiratory condition. Once a cat has become infected with rhinotracheitis, it is a lifelong carrier. While the virus may become latent, stress or illness can cause the virus to become reactivating. Cats with even latent infections can still spread the virus to other cats. This is the last portion of the core FVRCP.
  • Feline Leukemia Virus (FeLV) – Feline Leukemia Virus is a virus that impairs a cat’s immune system and can lead to cancer in some cats. This disease is spread through the saliva of infected cats, so this vaccine is best for cats that are exposed to other cats with unknown FeLV status. Cats that spend any time outside should be vaccinated for FeLV. This non-core cat vaccine can be administered to kittens as early as 8 weeks, then 3-4 weeks later, and to adult cats (2 doses, 3-4 weeks apart). Subsequent vaccinations should be done on an annual basis. Any cat being vaccinated for FeLV for the first time should be tested prior to ensure it is not already infected with the virus.

Here at Mount Carmel Animal Hospital, We’ll Treat Your Pets Like Family!

Mount Carmel Animal Hospital has been serving the Northern Baltimore/Southern York community for over 30 years and is proud to be an independently operated, small animal practice committed to excellence in veterinary medicine and client service. From grooming to wellness services, along with Canine Life Skills Training Courses, and surgical procedures, we have the expertise that will best serve the needs of you and your pet. Contact us at 410-343-0200 and follow us on Facebook!

This entry was posted on Thursday, August 4th, 2022 at 6:23 pm. Both comments and pings are currently closed.