Pet Vaccinations 101

Pet Vaccinations

What vaccines does my pet need?

Are vaccines and annual boosters really necessary?

What does each vaccine prevent against?

Are there adverse side effects to over-vaccination?

These are just a few of the questions we get on a regular basis regarding vaccines. Keeping track of the various pet vaccines and their associated inoculation schedules can be confusing and a bit overwhelming. Coupled with the often heated and sometimes emotional national discussions regarding the safety and efficacy of vaccines, you may wonder if it’s worth vaccinating your pet at all. Well, we’re here to tell you it is!  We want to cut out all of the confusion and give you the facts about vaccines and why they are an essential part of your pet’s preventative wellness care, helping your furry companion lead a long and healthy life!

What are vaccines? How do they work?

Vaccines offer the greatest protection against specific infectious diseases caused by a virus or bacteria. We offer vaccinations for common dog and cat diseases that attack the immune, gastrointestinal, and respiratory systems.

Vaccines are made from chemically-altered forms of the virus or bacteria that won’t cause a disease, but stimulate the body’s immune system to produce antibodies against the disease instead. Antibodies work by destroying the disease-causing virus or bacteria if it tries to infect the body, then “remembers” it, to fight against the disease in the future. The protection provided by vaccines gradually decreases over time and is specific to each vaccine. This is why boosters are required. Many vaccines are on an annual booster schedule, however some require a booster every six months (like kennel cough) and others can be once every 2-3 years.

Of course, not all pets need all vaccines. The vaccines your pet needs depends on their age, health status, lifestyle, and what diseases are present in our area. At Leesburg Veterinary Hospital, we tailor vaccine plans to each indivdiual pet, so we are not “over-vaccinating,” but providing the best comprehensive protection for that pet based on their lifestyle and risk factors.

We’ll discuss LVH’s recommended vaccines and immunization schedules below.

Importance of Pet Vaccines Vaccinations Leesburg Veterinary Hospital

Vaccines offer the greatest protection against specific infectious diseases caused by a virus or bacteria. We believe strong communication between you and your LVH veterinarian is the key to getting your pet on the appropriate vaccination schedule. Image: Ellen Zangla Photography


The Disease

Rabies is an extremely serious (most-times fatal) virus that infects the brain and spinal cord of all mammals (including humans!). Rabies is spread through the saliva of mammals, most commonly by wildlife such as foxes, bats, raccoons, skunks, cattle, wild dogs and feral cats. Your pets would most likely get rabies by getting bit by a wild animal infected with the virus.


Seizures, aggression, depression, excess salivation, weakness, coma


Vaccination is the most effective way to prevent the transmission of the disease in animals.  Vaccinating animals is the best safeguard to prevent the spread of rabies to human as well.

Because of the serious health risks to both pets and humans, the rabies vaccine is required by law in most areas of the country, including Virginia. Virginia law states that all domesticated dogs and cats must be rabies vaccinated by four months of age by a licensed veterinarian (this is why rabies vaccines cannot be administered by our LVTs at technician appointments). All dogs living in Loudoun County must be licensed with the county. This license runs concurrently with each pet’s rabies vaccination schedule, therefore if a dog does not receive their rabies booster, they will not be lawfully licensed in the county. While cats do not need a license, their rabies vaccine should always remain up-to-date. This includes indoor cats too! There have been cases where rabid bats have gotten into people’s homes or indoor cats have accidentally gotten outdoors, potentially exposing themselves to rabid animals.

Related to older pets, there are very few cases where we would not keep an older pet updated on their rabies vaccine. We still advise cats with kidney disease, hyperthyroidism, many cancers, diabetes, etc. to keep their rabies vaccination status current. Of course, every pet’s medical history and conditions are different. Our veterinarians will determine the best option for your pet.

Importance of Pet Vaccines - Rabies Vaccine - Leesburg Veterinary Hospital

Rabies Vaccine Schedule                                     

Puppies and Dogs:

  • 1st vaccine between 12-14 weeks of age
  • Booster at 1-year exam
  • Every 3 years thereafter.

Kittens and Cats:

  • 1st vaccine between 12-14 weeks of age
  • Booster at 1-year exam
  • Every 1 or 3 years thereafter (Your veterinarian will work with you to determine the best rabies vaccine schedule for your pet).


Canine Immunizations


DHPP is a combination vaccine. When not named using the acronym above, it is commonly referred to as just canine distemper. The vaccine also protects against hepatitis, parvovirus, and parainfluenza. Along with rabies, DHPP is considered a “core” vaccine by the American Animal Hospital Association. Core vaccines are recommended for all pets because they protect against serious, highly contagious, and oftentimes fatal diseases.

Importance of Pet Vaccines - What is Canine Distemper DHPP Vaccine - Leesburg Veterinary Hospital

D = Distemper

A life-threatening virus that attacks the respiratory, digestive, and brain/nervous system of dogs. Distemper is highly contagious, spread from one dog to another through respiratory secretions from coughs, sneezes, and eye discharge.  Symptoms include vomiting, diarrhea, pneumonia, and seizures.

H = Hepatitis

Caused by canine adenovirus-2 and adenovirus-1 and transmitted among dogs by contact with secretions such as saliva, urine, or feces.  Hepatitis causes liver failure, eye damage, and respiratory problems. Symptoms are similar to those in the early stages of distemper.


A highly contagious and life-threatening virus that attacks the digestive and immune systems and is spread through infected feces. The disease is more commonly seen in puppies. Symptoms include severe vomiting and diarrhea and usually requires several days of hospitalization to treat.

P = Parainfluenza

A highly contagious viral respiratory infection that is a contributor for “kennel cough” in dogs. We’ll go into kennel cough in greater detail when we discuss its other contributing virus, bordetella.

 DHPP Vaccine Schedule

Puppies will receive a series of three DHPP vaccines by the time they are five months old. Healthy pups nursed from a healthy mother receive antibodies in their mother’s milk that will protect the pup and help him/her build immunity until the first round of vaccines at 8-10 weeks old:

  • 1st DHPP – 8-10 weeks
  • 2nd DHPP – 12-14 weeks
  • 3rd DHPP – 16-18 weeks
  • Booster at one year exam, then every 3 years thereafter
Importance of Pet Vaccines Vaccinations

Puppies will visit the veterinarian several times before they are 6 months old. At these wellness exams, puppies will receive their initial vaccines or a booster if needed. These visits are a great time to discuss any questions or concerns with your veterinarian as you adjust to life with a new pup! Image: Ellen Zangla Photography



The Disease

Leptospirosis is a contagious bacterial disease carried by wild animals such as deer, raccoons, mice, and cows. It is spread through an infected animal’s bodily fluids (urine, specifically) or by drinking contaminated water from lakes, streams, etc., and is absorbed through the skin and mucous membranes. Leptospirosis can be passed from pets to humans.


Severe diarrhea, vomiting, dehydration, weakness, liver and kidney failure


Pets exposed to potentially contaminated water such as streams or ponds, go walking on hiking trails, or swim in our local rivers and lakes are at risk for leptospirosis. We recommend all of our canine patients who fit this criteria be vaccinated against leptospirosis. 

Leptospirosis Vaccine Schedule

Leptospirosis is available as part of the distemper combo vaccine (DHLPP). Puppies will receive the leptospirosis vaccine as a 2 series booster during the DHPP vaccination between 12- 16 weeks of age as discussed above, then once annually. Since the distemper vaccine is only given every 3 years after year 1, the leptospirosis vaccine is given individually on the years when distemper is not needed.


Lyme Disease

The disease

Lyme disease is a bacterial infection transmitted through tick bites, most commonly by the deer tick.   Lyme disease can be transmitted to both dogs and humans from tick bites. It is not transmitted directly from animal to animal or from dogs to people.


Lyme disease is a debilitating disease causing joint pain and arthritis, decreased appetite, fever, lethargy, and in more rare cases, kidney or heart failure


Lyme Disease is extremely prevalent in Loudoun County. While we have one of the highest rates of Lyme infection in the country, it is preventable through a combination of regular tick checks by you, vaccination, annual blood testing, and a year-round preventative such as Frontline. We highly recommend all of our canine patients be vaccinated against Lyme Disease. Remember, deer commonly roam in residential neighborhoods and yards, so even dogs that are mainly indoors can contract Lyme Disease when they’re out to go to the bathroom.

Importance of Pet Vaccination - Canine Lyme Vaccine - Lyme Disease

Lyme Vaccine Schedule

The initial Lyme vaccine can be given during the puppy exams with a booster 2-4 weeks after:

  • 1st Lyme – 12-14 weeks old
  • 2nd Lyme – 16-18 weeks
  • Annually thereafter

*An update on our Lyme Vaccine:

Leesburg Veterinary Hospital strives to practice the best medicine.  A more protective Lyme vacccine (Zoetis’ crLyme vaccine) is now available to the veterinary profession and we have chosen to offer this vaccine in our preventative medicine repertoire. To receive the full protective benefits of this annual vaccine, a first time inoculation is advised, followed by a booster in 3-4 weeks.  For pets who have already been vaccinated with our previous Lyme vaccine, an initial inoculation followed by the booster with the new vaccine is recommended by our doctors. 

Bordetella (Kennel Cough)

The Disease

An infection of the trachea (windpipe) and the large air passages of the lungs. It is caused by the bacterium bordetella bronchiseptica, and the virus, parainfluenza.   Kennel cough is highly contagious and earns its name because it is easily transmitted through direct contact or through the air and rapidly spreads where dogs are confined together, such as kennels, dog parks, pet stores and grooming facilities.


A harsh, dry cough, sneezing, retching, gagging, vomiting


Vaccination is the best preventative measure against kennel cough. We recommend the kennel cough vaccine for all dogs that have the potential to come into contact with infected dogs in public places.

Bordetella Vaccine Schedule

For puppies:

  • 8-10 weeks old – Intranasal vaccine
  • Booster at 12-14 week exam with injectable vaccine
  • Then every 6 months if exposure risk is high.

For adult dogs:

  • A series of two injectable vaccines, 2 weeks apart
  • Then every 6 months, if exposure risk is high.

Recommended time to get vaccine before potential exposure: TWO WEEKS prior to boarding, visiting parks, puppy classes, etc.


Feline Immunizations


The FVRCP is the core vaccine for cats. It is a combination vaccine, protecting against three serious airborne viruses – viral rhinotracheitis, calicivirus, and panleukopenia. It is commonly referred to as the feline distemper vaccine.

Importance of Pet Vaccination - What is the Feline Distemper FVRCP Vaccine - Leesburg Veterinary Hospital

R = Rhinotracheitis

An upper respiratory infection caused by the common feline herpes virus. Symptoms include sneezing, drooling, runny nose and eyes, lethargy, and decreased appetite.

C = Calicivirus

An upper respiratory infection with symptoms and clinical signs similar to rhinotracheitis. This virus prefers the oral cavity, so oral ulcers are also common; if left untreated, pneumonia can occur. Kittens and senior cats are most susceptible to the virus.

P = Panleukopenia (feline distemper)

Commonly referred to as feline distemper (but not related to canine distemper), this viral infection is extremely common and highly contagious among non-vaccinated cats. It is common in kittens who have not been vaccinated yet or strays that have exposed to feral cat colonies, other shelter cats, etc. The virus is especially harmful to young kittens as the virus attacks the new white blood cells in the bone marrow and intestinal tract, causing fever, respiratory illness, and severe vomiting and diarrhea.

FVRCP Vaccine Schedule
  • 1st FVRCP Vaccine – 8-10 weeks old
  • 2nd FVRCP Vaccine – 12-14 weeks old
  • 3rd FVRCP Vaccine – 16-18 weeks old
  • Booster at 1 year exam, and every 3 years thereafter (Your veterinarian will work with you to determine the best rabies vaccine schedule for your pet).

Feline Leukemia Virus (FeLV)

The Disease

A virus that only affects cats, it is the most common cause of feline cancer (lymphoma), responsible for various blood disorders, and immune deficiency. Because it suppresses the immune system, it predisposes exposed cats to serious infections. FeLV is spread from one cat to another through bodily fluids – saliva, blood, and to some extent, feces and urine. Transmission can also occur from an infected mother to her kittens, either before they are born or during nursing. Cats at greatest risk for infection are those allowed outdoors where an infected cat may bite them or those exposed to cats of unknown infection status.


Decreased appetite, weight loss, poor coat condition, enlarged lymph nodes, inflammation of the mouth and gums.


Keep indoor cats indoors! If you do allow cats to go outside, supervise them and provide an enclosed space to keep them from wandering or fighting with other cats. We strongly recommend the FeLV vaccine for all cats that spend any time outdoors.

FeLV Vaccine Schedule
  • 1st FeLV Vaccine – 12- 14 weeks old
  • 2nd FeLV Vaccine – 16 – 18 weeks old
  • Booster annually
Importance of Pet Vaccinations - Leesburg Veterinary Hospital

Our furry feline friends need vaccines to stay healthy too! Your LVH veterinarian will work with you to determine the best vaccines for your cat’s lifestyle. Image: Ellen Zangla Photography.


Are there risks associated with over-vaccination or adverse side effects to vaccines?

Vaccinations are one of the best tools we have in preventive veterinary medicine. Vaccines have protected millions of animals from illness and death caused by infectious diseases. The key to using vaccines appropriately is to determine which diseases your pet may be at risk for and then vaccinate for those diseases no more than necessary. As we mentioned above, the vaccines your pet needs depends on their age, health status, lifestyle, and what diseases are present in our area.

Vaccines work by mildly stimulating an animal’s immune system in order to create protection from specific infectious diseases. Because of this, pets may experience mild side effects after receiving a vaccine, usually starting within hours of the vaccination. This includes:

  • Discomfort or localized swelling at the vaccination site
  • Mild fever
  • Decreased appetite and activity
  • Sneezing, mild coughing, runny nose, or other respiratory signs may occur 2-5 days after an intranasal vaccine

These symptoms should last no longer than a day or two. Many pets experience no symptoms at all.

Far less common, more serious allergic reactions may occur. These reactions usually occur more quickly, within minutes or hours of vaccination and require immediate veterinary care. These symptoms include persistent vomiting and diarrhea, itchy skin that looks bumpy (similar to hives), swelling of the muzzle, face, neck, or eyes, severe coughing, difficulty breathing,

With that in mind, we believe the benefits of vaccinations far outweigh the risks and are vital in keeping your pet healthy against infectious diseases. More importantly, we believe strong communication between you and your LVH veterinarian is the key to getting your pet on the appropriate vaccination schedule.   With the facts in hand, you can now feel prepared to discuss the various vaccines or ask questions at your next appointment!









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