Dog Shot Schedule: All You Need To Know About Your Dog’s Vaccinations

By: Dr Pippa Elliott
Last Updated:

The world can be a big scary place for a pup, and that’s without hidden dangers such as viruses lurking in the environment. Happily, you can shield your fur-friend from serious viral diseases by getting him vaccinated and keeping to the dog shot schedule.

But perhaps you’ve heard confusing, and sometimes conflicting advice about when to vaccinate, what to vaccinate against, and the risks of side effects. Actually, this is not surprising because dog shot schedules do vary and vets no longer take a ‘one-size-fits-all” approach.

Indeed, there are lots of factors that influence these choices, which is why your vet puts a lot of thought into their vaccine protocols and providing the most appropriate cover for dogs in that area.

Current Thinking About Dog Shot Schedules

To understand why schedules differ, let’s explore the latest trends in vaccine medicine and science.

Increasingly, vets use tailored vaccine schemes which weigh up the risk of disease in that area; the aim being to protect dogs but without giving unnecessary shots.

The factors the vet considers when creating a dog shot schedule include:

  • Which diseases are prevalent in that area
  • How long each vaccine component protects the dog for
  • Shots required by law (such as rabies vaccine in the US)
  • Special infection risks that an individual dog faces

To the eye, the dog gets the same needle every year…but it’s what’s inside the syringe that counts. For example, some years the shot is a cocktail, containing more than one ‘ingredient’, whilst other years the shot protects against a single disease. Thus, although your dog has a single yearly booster injection, the components vary year on year.

The Diseases Commonly Vaccinated Against

So what’s likely to be that syringe, especially when a puppy visits for his first shots?

The diseases most commonly covered in a dog’s shot schedule are:

  • Distemper: Also known as ‘hardpad’ from one of the side effects, distemper is caused by a paramyxovirus. Infection results in respiratory infection, severe sickness and diarrhea, and neurological damage. With intensive care, some dogs do survive but can be left with long-term problems such as seizures.
  • Parvovirus: This virus is particularly tough and can survive in the environment for years. Even totally indoor dogs are at risk because you can walk infection inside on shoes. The main symptoms are profuse bloody diarrhea, leading to severe dehydration and anemia, circulatory collapse, and death.
  • Canine adenovirus: Also known as infectious canine hepatitis, this virus causes liver damage. Some dogs may recover from mild infection, but the condition is often fatal. In addition, recovered dogs continue to excrete the virus for up to one-year, and therefore pose an infection risk to other dogs.
  • Parainfluenza Virus: This is equivalent to a doggie-flu virus and is often linked to pneumonia complications.
  • Leptospirosis: This disease is of special significance because it also poses a risk to people (as Weil’s disease). It causes catastrophic liver and kidney failure, varying in severity from fatal to carrier status (The latter refers to mildly affected dogs that shed leptospirosis in their urine, posing a risk to other dogs and people).
  • Bordetella Bronchiseptica: This is one of the causes of the respiratory illness known as kennel cough. The vaccine is slightly unusual in that it is not an injection, but drop administered up the dog’s nose.
  • Rabies: This lyssavirus infection is fatal and transmissible to people. In most US States rabies vaccination for pets is compulsory by law. However, in rabies-free countries, the vaccine is not given unless the dog is traveling to locations where the disease is present.
Ensuring your Dog follows their vaccination schedule means that you give it the best chance of a healthy life free of diseases.

How Vaccines Work

Vaccination works on the simple idea of training, in a safe way, the immune system to fight off infection should it come along for real. To do this the vet injects a small volume of the vaccine under the loose skin of the scruff.

The vaccine may either be ‘live’ which contains a harmless version of the bug, or ‘dead’ where the infectious agent has been made safe using heat or chemicals.

Both live and dead vaccines have advantages and disadvantages. For example, live vaccines tend to protect for longer, but carry a slightly higher risk of side effects. Whilst dead vaccines have fewer side effects but may not work for as long. Now you begin to see why the topic is so complicated!

How Often Does My Dog Need To Be Vaccinated

Great question!

For core vaccinations, the simple answer is the puppy or dog has a starter course of two injections, three to four weeks apart. Thereafter the dog has a single booster injection, year after year, thus:

Puppy Vaccination Schedule

  • Two Injections two to three weeks apart
  • Last injection given after 10 weeks of age (depending on the vaccine brand and country)
  • Then a yearly booster injection for life

Naive Dog (not previously vaccinated) Vaccination Schedule

  • Two Injections three to four weeks apart
  • Then a yearly booster injection for life

Each year your vet does the heavy-lifting brainwork and decides what goes into the syringe. This is because certain diseases (for example parvo and distemper) create longer-lasting immunity and can be given less often, than others (such as leptospirosis).

Therefore, a typical dog shot schedule might include a yearly leptospirosis vaccine with other elements (parvo, distemper, infectious canine hepatitis) added in every third or fourth year. Confused? Well, don’t be because it’s your vet’s job to have a headache for you.

What’s The Difference Between Puppy Shots and an Adult Booster Injection?

Actually, the difference isn’t so much about what’s in the syringe, but the way the immune system works. Indeed, an adult dog with lapsed vaccines also needs two shots, just like a puppy, to get adequate protection.

To understand why think of the vaccine as ‘teaching’ the immune system to protect the body. A single shot (or the first puppy vaccine) wakes up the immune system and sets it thinking. However, within a couple of weeks, the immune system has forgotten the lesson and gone back to sleep. If the dog encountered real disease now, he’d be vulnerable to infection.

That second shot, usually given three to four weeks after the first, makes the immune system do its homework. This time it learns well and remembers the information for a year or more, so the body can quickly mount a response in the face of real disease.  Then, every 12-months, a single booster injection reinforces the previous class so it’s not forgotten.

Essential Vs Non-Essential Vaccine Elements

Just when you thought everything made sense, here’s another level of complexity…ahem… further options. Also known as core and non-core vaccinations, these refer to whether a certain vaccine is considered essential or optional.

As the name suggests, essential or core vaccines are the no-brainer components, giving protection against deadly infections such as parvovirus, distemper, and adenovirus.

As an aside, this is also a great illustration of how things vary between countries, because in the US the rabies vaccine is core (indeed, in many states it’s required by law) but in the UK (a rabies-free country) it is not given (non-core) unless the dog travels abroad. Got it!

Dog being cared for by vet
It is always best to follow veterinary advice and get your dog vaccinated accordingly

Another interesting example is leptospirosis. In the UK, lepto is given as a matter of course, indeed, the latest vaccine protects against not just two strains (as previously) but four types of leptospirosis.

However, hop over to the US and many states consider lepto as non-core since there are large areas free from infection. Complicated, isn’t it!

Let’s see if you’re keeping up, with another example of a non-core vaccine, Bordetella (Kennel cough). Although kennel cough is unpleasant, it rarely kills. Thus, it’s considered non-core. However, if the dog is at increased risk, such as an elderly dog with a heart condition or a dog that mixes with lots of other dogs, then the vaccine is given. Easy!

Puppy Vaccination Schedules

How many shots and when depends largely on where you live. For example, UK puppies usually have two shots, whereas US puppies have three or even four. Why the difference?

Puppy vaccination schedules are a hot topic and subject of much debate. When vaccines were less sophisticated than in the modern day, repeated shots were required because of ‘maternally derived antibodies’ (MDA). This is the temporary protection the mother passes, via her milk, to the pups.

Not only do MDAs protect against disease, but they can render vaccines ineffective. MDA protection ebbs away after several weeks but the exact timing varies from pup to pup. In order to be sure the vaccine had ‘taken’, this meant giving repeated shots up to the date (often 16 weeks) when it was extremely unlikely that MDA would interfere.

Hence some puppy vaccination schedules (mainly those in the US) rely on monthly injections up to 16 weeks of age. However, extensive research on UK vaccines, tells a different story. UK vaccine datasheets created by the manufacturers recommend a different protocol.

Here just two vaccines are sufficient, with a final vaccine as early as 12 weeks (or even 10 weeks for the most advanced vaccine available.) The vaccine manufacturers have gone to considerable time, effort, and expensive to prove this schedule is sufficient. Moreover, in real life, UK dogs seem adequately protected. Go figure!

Vaccine Side-Effects

Obviously, you want the best for your pup and desire to protect him rather than make him sick. Indeed, over the years there has been a lot of discussion about the safety of vaccines and if they are over-used.

Hopefully, you now understand that the modern vaccine protocols minimize the risk of over-vaccination. But this is different to ‘no risk at all’, so what could happen if something goes wrong?

So what are the risks and how serious are they?

Minor Side Effects

In the same way that a human baby can become feverish and unsettled after vaccination, a similar thing can occasionally occur with puppies. This raised temperature and restlessness is brief, lasting no more than 24 – 48 hours, after which the pup bounces back. [*] Again, this is most likely to occur in the very young animal and rare in adults.

Around one-in-ten dogs will get a soft swelling at the injection site. This is present almost immediately and may take a few weeks to disperse. It is of no long-term consequence and represents an active immune system working hard to process the vaccine.

Also, around one in every 1,000 to 10,000 dogs may experience a tummy upset after vaccination. Again, this is self-limiting and quickly settles down with a couple of days of bland food.

Major Side Effects

Rare as they are (around one in ten-thousand) anaphylactic or shock-type reactions to vaccines can occur. This is the equivalent of a person with nut allergy eating a peanut.

The body reacts in an inappropriate way to the vaccine, sending the animal into circulatory shut-down and profound shock if not treatment is given.  This collapse usually occurs within 20 -30 minutes of the vaccination. Prompt emergency treatment for shock is needed and can be life-saving.

Unknown Factors and Potential Risks

There has been a concern, especially in the US, about cancers forming where a vaccine was injected. However, this is extremely rare and limited mainly to cats rather than dogs.  It also seems to be linked to certain types of vaccine (the rabies vaccine was in the spotlight for a long time), possibly because of an added ingredient used to stabilize the vaccine.

Research into this is on-going and given the extreme rarity in dogs, acknowledged but not dwelt on.

Occasionally cases emerge of dogs that several weeks after vaccination became sick with autoimmune disease. The latter refers to illness where the body attacks its own tissues. Again, there is no proven link but some vets avoid against vaccinating dogs that have recovered from auto-immune disease, just in case it is a trigger factor.

Again, given the rarity of these cases, there is no firm evidence one way or the other.

Finally, let’s be clear that the risk from diseases such as parvovirus is very real. If your pup picks up a serious viral disease then he will become very sick and quite possibly die. This is fact. However, the risk of serious complications from a vaccine is rare. So when deciding whether or not to vaccinate, always keep an eye on balancing a high risk (serious infection) against a low risk (vaccine complications) and make an informed decision for your best buddy.


Vaccine advice for pet owners – Veterinary Medicines Directive.
First Year Puppy Vaccinations. American Kennel Club
Routine Health Care of Dogs. Merck Veterinary Manual
Versican vaccine datasheet, NOAH
Contraindications and Warnings. Versican Datasheet. NOAH
Vaccines for Dogs. VCA Hospitals

In-Depth Papers:

VMD Position on Dog Vaccination Schedules: UK
WSAVA Position on Dog and Cat Vaccinations: US

Photo of author


Dr Pippa Elliott
Dr. Pippa graduated as a veterinarian from Glasgow University in 1987. Since then she has worked in companion animal practice and has a special interest in internal medicine. Pippa is housekeeping staff to a naughty puggle, three cats, and a bearded dragon.

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