Vaccines are biological agents administered to healthy dogs which trigger the dog’s immune system to produce antibodies which will fight off the invaders. A vaccine contains minute doses of the micro-organisms which cause disease, which are sufficient to stimulate the immune system into action, but not enough to cause illness. The antibodies produced by the vaccine remain in place to fight off the disease should the dog subsequently be exposed to it.

The conditions vaccinated against vary from country to country: in the UK we do not need to vaccinate against diseases which are not prevalent here, unless the dog will be travelling abroad. Each condition vaccinated against requires a different vaccine, but these are usually combined into a single injection as this reduces the stress for the dog.

Why You Should Vaccinate Your Puppy

Vaccinations safeguard the long-term health of your puppy. Even here in the UK where the majority of dogs are vaccinated, it is likely that your dog will be exposed to at least some of the diseases against which vaccination will protect him. Any vet will tell you that they continue to receive dogs suffering from parvovirus and other preventable diseases on a regular basis, so do not imagine that the risk is negligible.

Like all young animals a puppy is more vulnerable to infection and disease than an adult dog, so it is important that a puppy is fully protected before he is allowed out. As he ages a dog’s immune system will strengthen through exposure to the outside world, but a puppy needs the protection of vaccination to ensure his safety.

Vaccination is not a legal requirement, but most dog groups, day care facilities and boarding kennels will want proof of vaccination before they will be willing to look after your dog.

What Diseases Do Vaccinations Protect Against?

In the UK, there are 4 core vaccinations which are recommended for all dogs.


Unvaccinated puppies are particularly prone to this highly contagious disease which attacks the intestine and causes acute (and often bloody) diarrhoea and vomiting. Other symptoms are lethargy, a high (or sometimes low) temperature and loss of appetite. Parvovirus also attacks bone marrow which can compromise the dog’s immune system. It is found in the faeces of infected dogs and can live in the environment for many years.

If treated early there is a good chance that a dog will recover from parvovirus, but the treatment is intensive and very expensive, usually running into thousands of pounds; and an unvaccinated dog may not be covered by insurance.

Canine Distemper

Distemper is rarer than parvovirus, but it is a particularly nasty disease that attacks the nervous system, gut and lungs. It can cause severe pneumonia (lung infection) and encephalitis (brain inflammation) and is usually fatal. Dogs who do recover may suffer from relapses, brain damage or have lifelong health problems.

Distemper spreads in the air and through the bodily fluids (saliva and urine) of infected dogs. Symptoms are fever (high temperature), runny nose (often with pus), diarrhoea, coughing, thickened nose and paws (hardpad), tremors and seizures. Being a virus there is no antibiotic available and treatment is palliative, and as for parvovirus, very expensive.

Canine Hepatitis

Also called Canine Adenovirus Type 1 and 2, these viruses cause an inflammation of the liver and can also affect the upper airway. It is transmitted via the bodily fluids of infected dogs, and in its mild form a dog may suffer only a loss of appetite and slight fever. Some dogs develop cloudiness of the cornea (called blue eye), and there may also be discharge from the eyes and nose, and coughing.

In severe cases (usually young puppies) there is vomiting, diarrhoea, edema (fluid swelling under the skin) in the head and neck, and jaundice. These cases are often fatal.

Being a viral infection there is no effective cure, and as in parvovirus and distemper only palliative treatment is available; often including intravenous fluids and treatment for secondary symptoms.


Leptospirosis (also called Lepto) is a bacterial disease affecting the liver and kidneys. It is spread by infected dogs, mice, rats and cows and is also found in stagnant water, so it is more likely to affect dogs who live on a farm, catch rodents or do a lot of swimming. It can infect humans, when it is commonly known as Weil’s disease.

Symptoms include loss of appetite, fever, jaundice, muscle pain, excessive drinking, vomiting, bloody diarrhoea, bleeding from the mouth and eyes and difficulty breathing. Mild cases can be treated by antibiotics and an intravenous drip, but the disease can often be fatal. Infected dogs must be treated in isolation.

There are two further diseases which can be prevented by vaccination; the need to vaccinate depends on the individual circumstances.

Kennel Cough

Kennel cough is the name given to infectious bronchitis in dogs and can be caused by a number of different viruses and bacteria. Unlike the preceding diseases kennel cough is not usually a serious condition, except in very young puppies or dogs whose health is already compromised by illness or old age, when it can develop into pneumonia. Most dogs will only suffer from a dry, hacking cough which will clear up by itself in a few weeks.

Kennel cough is airborne and highly contagious and spreads like wildfire among dogs living in close proximity, hence its colloquial name. Many boarding kennels will insist on vaccination before accepting your dog, which is usually administered as nasal drops or spray. Immunity is effective within days and lasts for 12 months.


Rabies, which is a severe and usually fatal viral disease, is not present in the UK and there are stringent protections against its import, so it is not necessary to immunise your dog unless you are planning to take him abroad. In that case it is a requirement, and your dog must be at least 12 weeks old and microchipped (now a legal requirement for all dogs from 8 weeks old). A delay of 21 days from the date of the vaccination is required before travel. Regular boosters are also required.

The rabies vaccine is always administered alone. Further information on taking dogs abroad can be found here.  

Choosing the Right Vaccination

Most canine vaccinations are administered by injection, and a puppy will require two separate injections administered at defined intervals. The intervals depend on which vaccine is used for leptospirosis; lepto 2 or lepto 4.

In the UK the most common forms of leptospirosis are Icterohaemorrhagiae and Canicola, and the leptospirosis vaccine used to protect against these strains has been available for many years; it is called the lepto 2 or L2 vaccine. But in recent years the vaccine has been strengthened and protection against two other strains of leptospirosis, Australis and Grippotyphosa (reported to be the most common strain in much of Europe) has been added; this called the lepto 4 or L4 vaccine.

If the dog will be travelling abroad then the greater protection provided by the L4 is probably advisable, but you should consult your vet before making a decision on which vaccine to use.

When to Vaccinate a Puppy

At birth a puppy is partially protected from infection by the antibodies passed to them through the milk of their dam (it’s vital, of course, that she should be up to date with her vaccinations). But the puppies will only be protected for their first few weeks; as they are weaned and drink less of their mother’s milk they will need other methods of protection. This can only be provided through vaccination.

Legally a first vaccination must be given by a qualified vet. Before administering the vaccination, the vet will give the puppy a thorough examination and will comment on any problems they find. No reputable vet would administer a vaccine to a puppy that is not in good health. The vet will provide a vaccine card which will record this vaccination and can be used to record all subsequent vaccinations. On each occasion stickers from the vials used to mix the injection will be attached to the card; this provides evidence of the manufacturer and the batch of the vaccines administered. This is particularly important in the case of any adverse reaction. If the breeder arranges the first vaccination, they will ensure this card is passed to the new owner when they collect the puppy.

The initial vaccination is a two-stage process. The first injection is administered at seven to eight weeks of age: the timing of the second stage depends on whether the puppy is being given the L2 or the L4 vaccine. With the L2 vaccine the second injection can be given anytime between 2 and 4 weeks after the first; with the L4 vaccine the second injection must be given exactly 4 weeks later. In both cases it will be another 7 days before it is safe to take the puppy outside to walk and to meet other dogs. Until then the puppy should always be carried when taken outside his house and garden.

A booster for all 4 core vaccinations should be given when the puppy is 1 year old. After that you should follow your vet’s advice; but it is essential that boosters for leptospirosis (and kennel cough if necessary) are given annually.

What are the Risks of Vaccination?

Most of the diseases that are nowadays protected against by vaccination are serious, painful, often incurable except by nature’s lottery, and frequently fatal. Vaccination can prevent this. It is also infinitely cheaper than it is to treat a serious infection.

In a small number of cases some dogs and puppies can suffer an adverse reaction to a vaccine. This is a known risk for all vaccinations; and must be set against the many fatalities which would happen – which do happen – when vaccination is bypassed. A reputable vet will never vaccinate a puppy with health concerns.

Recently there have been concerns about the leptospirosis L4 vaccine. Originally it was intended that the L4 vaccine should replace the L2, but because of the various scares that so often accompany a new vaccine, both continue to be available. Data collected to date indicates a 0.015% risk of a suspected adverse reaction for the L2 vaccine and a 0.069% risk for the L4. Note the ‘suspected’: it cannot always be said with certainty that an untoward reaction was due to the vaccine.

Sometimes a dog or puppy may have a minor rash or sensitivity around the injection site, especially if the microchip was inserted at the same time. A puppy might also be a little quieter and more subdued than usual after the injection. This should resolve itself within a few days. If there are any health concerns about a puppy these should be raised and discussed with the vet before vaccination.

A good vet will not try to override the puppy owner’s concerns. You should always discuss any worries with your vet before agreeing a course of treatment, including vaccination.  You are the person who knows your dog best.