Canine Vaccinations

Vaccinations can be a hotly debated topic among dog owners.  Obviously we want to protect our pets against everything possible, so it would make sense to vaccinate them with everything that is available.  However, some vaccinations can do more harm than good.  Therefore to do the best for your pet, you should become as knowledgeable as possible about the different vaccines, their efficacy and the possible reactions that your pet could have to them, so that you can make an intelligent decision about what vaccines your pet should have without just taking someone else's word for it.  I have been asked numerous times what vaccine schedule my own dogs are on and why, so I have decided to put together a comprehensive summary for each of the following vaccines and what they are supposed to protect against.  Before I get into the specifics of each vaccine, I want to mention that each breed of dog has different sensitivities to different vaccines, so you need to research for your specific breed.  I also want to urge you not to let your dog receive a Rabies vaccine at the same time as a combo shot (usually DHPPv or DHLPPv).  All of those vaccinations given at the same time put a lot of stress on your dog's immune system and they are more likely to have a reaction to the vaccine.

Distemper (D)
Hepatitis/Adenovirus (H/A2)
Parainfluenza (P)
Parvovirus (Pv)
Bordetella (KC)
Leptospirosis (L)
Coronavirus (C)


"First Milk"

Before discussing vaccinations, it is important to have an understanding of Colostrum.  Colostrum is the first milk that puppies receive from their mother in the first 24 hours after their birth.  This milk is rich in nutrients, vitamins, and fluids that the puppies desperately need.  It also contains the mother's antibodies against disease.  Newborn puppies' immune systems are not fully developed when they are born, so they must rely on the antibodies that they receive from their mother through the Colostrum.  The problem is one of timing.  The mother's antibodies will only protect the puppies for so long and then they must be vaccinated.  If they are vaccinated while the mother's antibodies are still effective, the vaccine's effectiveness will be blocked, therefore, the puppies will not be protected in the long run.  If the effectiveness of the mother's antibodies runs out before the puppies have been vaccinated, they will be susceptible to disease.  This is why we give booster shots.

Window of Susceptibility from

The antibodies from the mother generally circulate in the newborn's blood for a number of weeks. There is a period of time from several days to several weeks in which the maternal antibodies are too low to provide protection against the disease, but too high to allow a vaccine to work. This period is called the window of susceptibility. This is the time when despite being vaccinated, a young animal can still contract the disease.

The length and timing of the window of susceptibility is different in every litter, and even between individuals in a litter. A study of a cross section of different puppies showed that the age at which they were able to respond to a vaccine and develop protection (become immunized) covered a wide period of time. At six weeks of age, 25% of the puppies could be immunized. At 9 weeks, 40% of the puppies were able to respond to the vaccine and were protected. The number increased to 60% by 16 weeks, and by 18 weeks, 95% of the puppies could be immunized.

As you can see, it is really impossible for us to determine, when in the presence of passive immunity, an individual animal should be vaccinated. There are just too many variables. Even if we did blood tests on them, each animal in the litter would probably have a different titer. Some will have absorbed more antibodies, the antibodies may have broken down more quickly in others, or some may have used a portion of their antibodies if they encountered harmful bacteria or viruses. Additionally, a young animal may have a protective titer (level of antibodies) for one disease but not enough for another.


Canine Distemper

The following information has been gathered from

Symptoms begin with:

The virus is attacking interfaces of the body with the environment (the “mucous membranes”) and starts with the respiratory tract, hence the pneumonia, but it does not stop there. The virus moves on to produce:

After completing what is called the “mucosal phase” of infection where environmental interfaces are attacked (as described by the above GI and respiratory disease), the virus proceeds to the central nervous system for its “neurologic phase” leading to:

This means that the dog appears to recover only to break with neurologic disease 1-3 weeks later. Younger puppies or individuals with weak immunity often die during the mucosal phase while stronger individuals may have relatively mild mucosal signs and not appear ill until the neurologic phase strikes.


The infected dog typically infects other dogs via coughing infected respiratory secretions though the virus is shed in most other body secretions including urine. The virus enters the new host via the nose or mouth


Many bizarre protocols have emerged over time as we grope for meaningful anti-viral therapy. The fact remains that recovery from distemper is all about immunity and the only real treatment is supportive care while the patient mounts its own immune response. If the patient has pneumonia, antibiotics are used on the secondary bacterial infections. Airway dilators are used as needed. Physical therapy is used to promote cough. If the patient has diarrhea, intravenous fluids are used to prevent dehydration etc.

Distemper is extremely variable in its ability to produce symptoms and recovery occurs at any stage. This has led to assorted therapies being credited with effect when what was more likely witnessed was the natural removal of the infection by  the host’s immune system.

Neurologic distemper is particularly difficult to treat. Still, it is possible for dogs to recover with livable deficits even from neurodistemper; euthanasia is best left for progressive, incapacitating neurologic symptoms.


If confirming diagnosis and therapy are the pitfalls of distemper, prevention is the easy part.  Effective distemper vaccination has been available since the 1950’s. Prior to widespread vaccination, distemper was the scourge of the canine community, wiping out entire townfuls of pet dogs. Today, distemper is a rare disease except in the shelter, rescue, and pet store world.

The “distemper shot” is the basic immunization for dogs. It is generally combined with vaccine for canine parvovirus as well for parainfluenza and adenovirus 2.  Puppies are vaccinated beginning at age 6-8 weeks and then every 2-4 weeks thereafter until age 16 weeks.

***Studies are currently being done that prove that immunity obtained from the Distemper vaccine last at least 7 and a half years and possibly for the lifetime of the dog.  Please do not give annual Distemper booster shots.  They are not needed.



The follow information has been gathered from

Canine adenovirus type 1 causes canine hepatitis. The virus invades the dogs liver, causing swelling, cell damage sometimes liver hemorrhage and often acute death due to shock. An infected dog will shed the virus in the feces and urine. Other dogs become contaminated via the mouth or nose and the virus then lodges in the tonsils. The virus is not airborne. The incubation period is 4 to 7 days.

Symptoms include fever, lethargy, tonsillitis, abdominal distension and pain, loss of appetite and a pale color. Often there is vomiting. Some dogs will develop the classic hepatitis blue eyes. This is due to edema (fluid swelling) of the cornea of the eye. In severe acute cases, especially pups, death can occur in 1 to 2 days. If dogs can survive the initial few days, they should recover and have lifelong immunity. However, regular vaccination is a preferential.

Canine adenovirus type 2 is related to the hepatitis virus and is one of the causes of infectious tracheobronchitis, also known as kennel cough. Vaccination against adenovirus-2 will not prevent infection with this virus but limits its severity so the chance of secondary bacterial infection and complications occurring is minimized. In most cases of kennel cough, the disease is multifaceted and will include a combination of bacterial and viral agents.

Normally, symptoms of kennel cough will develop within a week after a dog has been exposed. The most common symptoms are a dry, hacking cough followed by retching, and coughing up a white foamy discharge. The cough is brought on by an inflammation of the trachea (windpipe) and bronchi (the air passages to the lungs). Some dogs also develop conjunctivitis ("pink eye"), rhinitis (inflamed nasal mucous membrane), and a nasal discharge.

***Studies are currently being done that prove that immunity obtained from the Distemper combo vaccine last at least 7 and a half years and possibly for the lifetime of the dog.  Please do not give annual combo booster shots.  They are not needed.



From Canine parainfluenza virus (CPIV) is an important cause of kennel cough in the USA and is commonly isolated from outbreaks of the disease.  Experimentally, the disease is only very mild or sub clinical. However, in the field CPIV infection may predispose dogs to combined infections with other viral and/or bacterial agents, leading to more typical signs of kennel cough.

This is one of the vaccines that is given in the Distemper combo shot. 

***Studies are currently being done that prove that immunity obtained from the Distemper combo vaccine last at least 7 and a half years and possibly for the lifetime of the dog.  Please do not give annual combo booster shots.  They are not needed.



The following information has been gathered from

Because the canine parvovirus is not enveloped in fat the way the distemper virus is, canine parvovirus is especially hardy in the environment. It is readily carried on shoes or clothing to new areas (which accounts for its rapid worldwide spread shortly after its original appearance).  It is able to over winter freezing temperatures in the ground outdoors plus many household disinfectants are not capable of killing it indoors.

The virus kills one of two ways:

Even though infection is somewhat unusual in adult dogs, adult dogs should still continue their vaccinations as this is a life threatening disease for which treatment is expensive and no chances should be taken.


The biggest problem in protecting a puppy against this infection ironically stems from the natural mechanism of protection that has evolved.  Puppies obtain their immunity from their mother’s first milk, the colostrum, on the first day of life.  This special milk contains the mother’s antibodies against parvovirus and until these antibodies wane to ineffective levels, they will protect the puppy.  The problem is that they will also inactivate vaccine.

Vaccine is a solution of inactivated virus, either live and weakened (“attenuated” or “modified”) or killed.  This virus is injected into the puppy. If there is still adequate maternal antibody present, this vaccine virus will be destroyed just as if it were a real infection.  There will be a period of about a week when there is not enough maternal antibody to protect the puppy but too much to allow a vaccine to work.  (This period is called the “window of vulnerability.”)  Then after this, the vaccine can be effective.

The next problem is the age at which vaccine can be effective is different for each individual puppy.

To get around this, vaccinations are given to puppies in a series, every 2-4 weeks until age 16 weeks. By age 16 weeks, we can be certain that maternal antibodies have waned and vaccine should be able to “take.”  It should be recognized that some individuals, especially those of well vaccinated mothers, must be vaccinated out to 20 weeks (unless a “high titer” vaccine is used.)

After a puppy is born, maternal antibody levels drop by half approximately every 10 days.

Puppies that were born first or were more aggressive at nursing on the first day, will get more maternal antibody than their littermates.

Mother dogs vaccinated at approximately the time of breeding will have the highest antibody levels to pass on to their puppies.

*** REMEMBER, the more maternal antibody a puppy has, the less likely a vaccine is to work.

It should be noted that giving vaccine more frequently than every 2 weeks will cause interference between the two vaccines and neither can be expected to be effective. This includes giving vaccines for different infections. Vaccines should be spaced 2-4 weeks apart.

It is commonly held that puppies need a certain number of vaccines for protection to be achieved (usually either 3 or 4 is the “magic” number). The number of vaccines given has nothing to do with protection. In order for protection to be achieved, vaccine must be given when it can penetrate maternal antibody.

***Studies are currently being done that prove that immunity obtained from the Distemper combo vaccine last at least 7 and a half years and possibly for the lifetime of the dog.  Please do not give annual combo booster shots.  They are not needed.


"Kennel Cough"
"Infectious Trachebronchitis"

The following information has been gathered from


Kennel cough is a bronchitis characterized by a harsh, hacking cough which most people describe as sounding like “something stuck in my dog’s throat.” It is analogous to a chest cold for humans and is only a serious condition in special circumstances (see below); in general, it  resolves on its own.

Classically, dogs get infected when they are kept in a crowded situation with poor air circulation but lots of warm air (i.e. a boarding kennel, vaccination clinic, obedience class, local park, animal shelter, animal hospital waiting room, or grooming parlor). In reality, most causes of coughing that begin acutely in the dog are due to infectious causes and usually represent some form of Kennel Cough.



Bordetella infection can be picked up by rabbits, guinea pigs, pigs, cats (if they are very young and housed in groups), and other dogs. It is not contagious to humans though it is closely related to Bordetella pertussis, the agent of Whooping Cough. Among dogs it is fairly contagious depending on stress level, vaccination status, and exposure to minor viruses.

Our hospital recommends keeping all dogs current on their Bordetella vaccinations as you never know when they be in an unexpected situation.


Although most cases will go away on their own, we like to think we can hasten recovery with antibiotics to directly kill the Bordetella organism. Alternatively, Kennel Cough may be treated with cough suppressants to provide comfort during natural recovery. Or antibiotics and cough suppressants can be combined.


In very young puppies, especially those with a recent shipping history (i.e. pet store puppies) are especially prone to severe cases of infectious tracheobronchitis (frequently progressing to pneumonia).

In dogs where the distemper virus is involved (usually shelter or pet store puppies), there is tremendous potential for serious consequences.


There are basically two options for Kennel cough vaccination:  injectable and intranasal.

Injectable is a good choice for aggressive dogs, who may bite if their muzzle is approached.  It provides good systemic immunity as long as two doses are given after age 4 months (with an annual booster). Injectable vaccination may only lead to less severe infection and not complete prevention.

Intranasal vaccination may be given as early as 2 weeks of age and immunity generally lasts 10-12 months.  (Usually this vaccine is boosted annually.) The advantage here is that the local immunity is stimulated, right at the site where the natural infection would be trying to take hold.

It takes 4 days to generate a solid immune response after intranasal vaccination so it is best if vaccination is given at least 4 days prior to the exposure.  Some dogs will have some sneezing or nasal discharge in the week following intranasal vaccination. As a general rule, nasal vaccination provides faster immunity than injectable vaccination.

Parainfluenza, Adenovirus type 2, and canine distemper, all members of the Kennel Cough complex, are all covered by the standard DHPP vaccine, the basic vaccine for dogs.  Adenovirus Type 2 serum also immunizes against Adenovirus Type 1, the agent of infectious canine hepatitis.




The following information has been gathered from

Dogs become infected by leptospires when abraded skin comes into contact with the urine of an infected host. The organisms quickly spread through the bloodstream leading to fever, joint pain, and general malaise which can last up to a week. The organism settles in the kidneys and begins to reproduce, leading to further inflammation and then kidney failure. Depending on the type of leptospire involved, other organ failure (especially liver) can be expected as well.  Make no mistake, leptospirosis is a life-threatening disease.

TYPICAL SYMPTOMS:  Fever, depression, loss of appetite, joint pain, nausea, excessive drinking, jaundice, excess bleeding brought on by low platelet count.

Fortunately, Leptospira interrogans is sensitive to penicillin, a readily available antibiotic. After penicillin has been used to stop leptospire reproduction and limit bloodstream infection, tetracycline derivatives are used to clear leptospires from the kidneys. Since tetracyclines and penicillins are not a good concurrent combination, often a combination of a penicillin with a fluroquinolone type antibiotic (such as enrofloxacin) is used to cover both phases of the infection.

Intravenous fluids are crucial to support blood flow through the damaged kidneys so that recovery is possible. Any areas at home that have been contaminated with urine should be disinfected with an iodine based product and gloves should be warn in cleaning up any urine. Prognosis is guarded depending on the extent of organ damage.


Vaccination options
Vaccination against Leptospira interrogans is only available for the serovars (strains) called canicola, grippotyphosa, pomona and icterohaemorragiae.  As a result of long standing use of this vaccine, it is hard to assess how important it is to vaccinate against leptospirosis. (As you might imagine, most recent outbreaks involve serovars (strains) for which vaccination does not exist.)

Vaccination against the four serovars mentioned is commonly included in the basic distemper shot (DHLPP - the “L” stands for “leptospirosis”).  The vaccine can be made up to omit the leptospirosis portion.  Of all the sera in this basic vaccine, it seems to be the leptospirosis portion that is associated with hives, facial swelling, and even life-threatening vaccination reactions much more than any of the other fractions. If there is any question of an animal having a vaccine reaction, leptospirosis vaccine is left out of the mix.

Vaccination will reduce the severity of disease but will not prevent infected dogs from becoming carriers.



The follow information has been gathered from

Symptoms, diagnosis, treatment, and control

The incubation period is only one to three days. The disease is highly contagious and is spread through the feces of infected dogs, who usually shed the virus for six to nine days, but sometimes for six months following infection. Symptoms include diarrhea, vomiting, and anorexia. Diagnosis is through detection of virus particles in the feces. Treatment usually only requires medication for diarrhea, but more severely affected dogs may require intravenous fluids for dehydration. Fatalities are rare. The virus is destroyed by most available disinfectants. There is a vaccine available, and it is usually given to puppies, who are more susceptible to canine coronavirus, and to dogs that have a high risk of exposure, such as show dogs.

The following information has been gathered from

This vaccine is not recommended for the following reason:



The following information has been gathered from

Giardia is a protozoan parasite that lives in the intestine of affected animals. It is unclear whether there are several species of this parasite or whether there is one species that affect several different animals, including people. These small parasites are very easy to miss on a fecal exam and may not be present in the stool of animals infected with the organism. Repeated fecal exams are sometimes necessary to identify this parasite. Not all animals in which infection can be demonstrated have clinical signs. This leads some people to believe that the parasite may not cause disease . Most vets think that there may just be other factors, like the animal's immune response to the parasite that cause some animals to develop disease and not others. Clinical signs of giardia include weight loss, inability to gain weight appropriately during growth, diarrhea, vomiting, lack of appetite and greasy appearing stools. The most commonly used medication for giardia infection is metronidazole (Flagyl). The organisms come from the environment and live in moist to wet areas. They are susceptible to quatenary ammonium disinfectants, Lysol and dilute chlorine bleach. Keeping the dog's environment dry helps a lot.

This disease may be contagious to people from infected dogs so good sanitary practices, like washing your hands after handling an infected puppy, are very important. If a family member develops similar clinical signs, a physician should be consulted.

From Canine Giardia

A waterborne protozoal parasite found in ponds, puddles, swimming pools and in the backyard. Giardia is transmitted to other animals by feces. Causes gastrointestinal problems in dogs. Symptoms can include diarrhea, weight loss, abdominal pain and vomiting.

From Canine Giardia spp. Vaccine

Around 90% of dogs respond to treatment for Giardia infection, most infected dogs are asymptomatic, and the disease is not usually life-threatening. The vaccine does not prevent infection but may reduce shedding and clinical signs. The zoonotic potential of Giardia remains unclear. Based on existing evidence, the UC Davis VMTH does not currently recommend routine vaccination of dogs for Giardia spp, and the vaccine is not stocked by our pharmacy.



The following information has been gathered from

The dogs most serious long term potential regards “glomerular disease.” This is a type of kidney damage that occurs when the immune system is stimulated over a very long time by a latent infectious organism (or other immune stimulus).

In dogs, Lyme disease is a minor infection not nearly worthy of the attention it has received.  Still, it is important not to discount Lyme disease in the dog completely lest one overlook an easily eliminated cause of chronic joint disease especially in dogs of the Northeast U.S.

The process that transfers the disease to the dog requires a minimum of 48 hours which means that if the tick is removed within 48 hours of attachment, the spirochete (disease) cannot be transmitted and the host will not get the disease.


Treatment of Lyme disease utilizes a 2-4 week course of doxycycline, a medication which is inexpensive and has limited side effects potential. Amoxicillin is another effective alternative, also inexpensive and with minimal side effects. If Lyme disease is a consideration, many veterinarians simply prescribe the medication. Obvious improvement is seen within 48 hours. Further, most tick-borne infections capable of causing joint pain, fever, and signs similar to Lyme disease generally all share doxycycline responsiveness so a simple course of medication actually covers several types of infection.


Tick control on the host is an effective means of infection prevention.  It is crucial in Lyme endemic areas to use tick controlling products.

On the West coast of the United States, there is minimal Lyme disease and virtually none from Calfornia to East Texas.

Vaccine prevents infection in dogs vaccinated before any exposure to Lyme spirochetes. This means it is only helpful for dogs not yet exposed such as puppies and dogs from non-endemic areas travelling to endemic areas. Annual boosters continue the vaccine-based immunity.

Argument Against Vaccination



From Rabies is the most feared disease, and is almost always fatal. Attacks the brain and central nervous system. Transmitted to humans through a bite or scratch of an infected animal. 

The law of when the Rabies vaccination is required differs across states, so you will have to check at what age it is required in your state to have your dog vaccinated against Rabies.  We personally don't give our dogs the Rabies vaccination until they are at least a year old (so their immune system is fully functioning) and we do not give it within 2 weeks of any other vaccine and the dog much be in perfect health when it receives the vaccine.  This vaccine can cause allergic reactions in animals and we want to give our dogs the best chance to accept it. 

***Studies are being done currently that prove that the immunity obtained from the Rabies vaccination lasts at least 3 years, so please don't get annual Rabies vaccinations when they are not needed.