Dog Vaccines: Are They Mandatory, and When Should They Be Given?

If we're going to share our life with a dog, vaccines are one of the veterinary measures we need to build into our preventive routine, whether our companion is a puppy or already an adult — regardless of whether they live indoors or outdoors.

There's a lot of misunderstanding and mistrust around vaccines, which causes people to lose sight of how vital they are in preventing fatal diseases. Below we clear up all the doubts and lay out the recommended vaccination schedule.

How do vaccines work?

To understand how vaccines work, we need to start by reviewing some basic immunology concepts. When an animal gets sick, its immune system creates defenses, known as antibodies, against the invading antigen.

This process fights the disease and, very importantly, creates immunological memory. This allows the body to react quickly on a second contact with the same pathogen, minimizing the illness. The problem is that the most serious diseases can cause the animal to die on first contact.

This way, the animal builds immunological memory and, if naturally exposed to the disease, will fight it off quickly, with a milder or even nonexistent clinical picture.

Microscopic virus

Why do dogs need to be vaccinated?

Dogs are exposed to different diseases in their day-to-day lives. Fortunately, most trigger a clinical picture that, while it can be complex, is usually treatable with veterinary care.

Other conditions, however, are potentially fatal, with nothing but supportive and symptomatic treatment available against them. Since the treatment to eliminate them is sometimes ineffective, science has focused its efforts on preventing them instead. And that's the job of vaccines.

Administering vaccines prevents and eradicates infectious diseases, contributes to public health by helping avoid zoonoses, and reduces antibiotic use, among other functions.

Types of dog vaccines

Vaccines can be made with live pathogens (with activity), attenuated ones (with some activity), or killed ones (no activity). The goal of this is to produce less reaction while providing good immunity. Sooner or later, all of them require revaccination.

Most vaccines are given by subcutaneous injection, but there are also intranasal or oral ones (like the kennel cough vaccine). Another way to classify them is between monovalent vaccines, which protect against only one disease, and bi-, tri-, tetra-, or polyvalent vaccines, depending on whether they include two, three, four, or more vaccines.

What is the vaccination schedule?

This is the name given to the protocol followed for administering vaccines. The schedule tells us which vaccines to give and when, also noting the necessary boosters and which vaccines are considered optional.

It's common for this to vary by country and even by region, and the dog's living conditions and characteristics always need to be taken into account. That's why it's best to adapt the schedule to each case and, if we're going to travel, find out about the requirements at our destination.

Which vaccines are recommended for a dog?

There are now numerous vaccines available to protect our dog. Most have been used successfully for years.

New vaccines will surely be developed in the future. In the following sections we'll go over the ones considered essential and the optional ones, and briefly describe the disease each one protects against.

Canine distemper vaccine

Distemper is a serious, highly contagious viral disease that affects puppies, especially unvaccinated ones between 6 and 12 weeks old. The clinical picture includes respiratory, digestive, and neurological symptoms. The after-effects can last a lifetime, such as dental enamel hypoplasia.

Mortality is high, especially when the nervous system is affected. This is one of the vaccines considered essential. It's given to puppies at 6 weeks of age, with boosters at the following two vaccination visits. Revaccination is recommended for adults.

Infectious hepatitis vaccine

This highly contagious viral disease is caused by canine adenovirus type I. It mainly affects dogs under a year old and primarily damages the liver. Clinical signs of infectious hepatitis can range from vomiting and jaundice (yellow mucous membranes) to corneal edema.

It can present with varying severity. In some very acute, severe cases, the dog dies within hours. This is one of the essential vaccines and also protects against the adenovirus involved in kennel cough (type 2).

Leptospirosis vaccine

Leptospirosis is a bacterial disease that tends to mainly affect the liver and kidneys. Its symptoms are related to these organs, though a wide variety of signs can appear. It's a zoonosis.

It's included in the combination vaccine, given at 9 weeks of age. It's recommended to repeat this dose annually. It's usually part of the standard schedule.

Parvovirus vaccine

Parvovirus is a very serious, contagious viral disease that mainly affects puppies just a few weeks old. It's characterized by intense vomiting and diarrhea, possibly with blood, which end up dehydrating the dog.

It's considered an essential, mandatory vaccine given to puppies and included in adult annual revaccination programs. It's a veterinary emergency, so if your puppy has diarrhea, the best thing to do is go to the vet immediately. Vaccination drastically reduces the chance of infection but not 100%, so you shouldn't let your guard down.

Rabies vaccine

Rabies is a fatal, zoonotic viral disease that, although controlled in developed countries thanks to vaccination, still causes human deaths in areas such as India. Giving this vaccine, which is considered essential, depends on the legislation where we live.

The first dose can be given to puppies at three months old and, based on scientific evidence, should be repeated every one, two, or three years, depending on the manufacturer. The issue is that it's usually a vaccine required by law, and it's the law that will specify when to give it.

Parainfluenza vaccine

Canine parainfluenza virus (included in the combination vaccine) is involved in kennel cough. This vaccine offers protection but doesn't stop infected animals from shedding the virus in their nasal secretions, meaning they'll still be contagious.

There's a combination vaccine with the Bordetella bronchiseptica vaccine that does prevent this. This is one of the vaccines that doesn't seem to provide protection for a full twelve months, so it would be advisable to give it twice a year in higher-risk dogs.

Bordetella bronchiseptica vaccine

This bacterium can cause kennel cough. In principle it's not a very serious disease, but in some dogs it progresses to pneumonia, which can carry a more guarded prognosis.

It's recommended for dogs that will be staying in places like boarding kennels, shelters, or taking part in dog shows, among others. The vaccine can be intranasal, injectable, or oral (the latest vaccine updates), and it's the one required for boarding at dog kennels.

Borreliosis or Lyme disease vaccine

There are also vaccines available that can help prevent humans from contracting Lyme disease. However, in dogs, consistent annual prevention against external parasites is more effective.

That said, prevention may differ in other countries where this disease is more prevalent, so you should always consult a vet in the area where you live, since disease prevalence varies from country to country.

Canine herpesvirus vaccine

It's transmitted through direct contact with respiratory or genital mucous secretions, although it generally causes no symptoms or clinical signs in its new host until some time later.

Puppies usually become infected in the womb, at birth, or through contact with littermates. In the case of transplacental transmission, the effects vary depending on the stage of pregnancy and are usually miscarriages. Vaccination is given to the pregnant mother, since the virus can infect puppies in the womb.

Leishmaniasis vaccine

This is a disease caused by a protozoan and transmitted by a mosquito. Since it can affect several organs, its symptoms are varied. In most cases it means lifelong treatment. A recombinant vaccine is now available. It can be used in dogs over six months old and is effective with two doses plus annual revaccination.

Beforehand, the dog's status regarding the disease must be assessed through serological tests, since it's only recommended for uninfected dogs in order to be effective. The vaccine doesn't act against the mosquito that transmits the disease, so annual deworming/parasite prevention remains essential, especially in endemic areas.

Which vaccines are mandatory?

On this point we need to check the legislation in force where we live. In Spain this authority has been transferred to the Autonomous Communities, which explains the differences between regions.

What's more, animal protection laws keep changing, so it's a good idea to check with your veterinary clinic. The vaccines we recommend, which are considered mandatory in some regions, are the ones we've classified as essential.

Whether to give all the others will depend on the dog's living conditions and characteristics. These factors determine the risk of contracting these diseases. It's the vet who will assess the need to give the corresponding vaccines. Then it's the owner who decides whether or not to go ahead.

Generally speaking in Spain, we can consider the following vaccines highly recommended, in addition to some that are fully mandatory by law, such as rabies.

1. At a month and a half, the dog should be vaccinated against parvovirus and distemper.
2. At two months and one week, the combination vaccine (booster for the previous two, plus leptospirosis, hepatitis, and parainfluenza).
3. The combination vaccine should be boosted at three months (the vaccine after which the dog can go outside). The kennel cough vaccine can be given afterward.
4. At four months, rabies. Leishmaniasis vaccination can follow.
5. Every year: combination vaccine booster and rabies vaccine (in some regions a booster is required every two years, in most every year).

Vaccinating puppies

Puppies, since their immune systems are still immature, are more prone to catching infectious diseases. To prevent this, it's essential to start vaccinating them as soon as the immunity passed on by their mother starts to wane, between 6-8 weeks. A single dose of a vaccine stimulates the immune system, but it's the second dose that provides nearly 100% immunity.

That's why puppies need the same vaccine repeated 2-3 times until optimal protection is achieved. It's recommended not to finish the booster series before 12 weeks. Until we've completed all the vaccines for this stage, it's important not to take the puppy out for walks. From the second combination vaccine or third vaccine onward, they can go outside.

Vaccinating adult dogs

Once the puppy vaccination schedule is complete, and adequate immunization achieved, the goal shifts to maintaining it. For this, the dog needs to be periodically revaccinated. Revaccination is usually annual and includes the essential vaccines. Depending on each dog's circumstances, the schedule may be adjusted.

When we adopt an adult dog whose vaccination history we don't know, or one that was vaccinated as a puppy but hasn't been revaccinated in years, the current recommendation is to give a single dose of the chosen combination vaccine as an essential booster. After that, boosters continue as with any other dog.

Vaccinating senior dogs

From around 8-10 years old, whether to continue with boosters is debatable. There comes a point where older dogs' immune systems are no longer able to respond to vaccination. Each case should be weighed on its risks and benefits. The rabies vaccine will keep being given due to legal requirements.

Why do we need to revaccinate?

The immunity provided by vaccines can be temporarily limited. This means the memory built up in the immune system after vaccination will fade over time. This varies depending on each vaccine. That's why revaccination is essential to maintain protection.

There's no debate about revaccination in general, but there is debate about exactly when each specific vaccine should be repeated. Vaccines against distemper, parvovirus, or rabies appear to maintain immunity for more than a year in an adult dog that was properly vaccinated. They're believed to potentially provide immunity for 3 to 9 years, or even for life.

On the other hand, other vaccines don't provide protection for a full twelve months. That's why it's worthwhile for the vet to design a vaccination schedule tailored to the dog's living conditions. It's also worth noting that some vaccines are sold combined, which is why revaccination is usually annual.

Keeping our dog properly vaccinated protects them, and it protects us too.

Can vaccines fail?

Yes, vaccines can fail to offer 100% protection — none of them do. The same applies if they're given to a dog that isn't in a condition to mount an adequate immune response. That's why it's so important to always go to a vet, to minimize errors. Also, some diseases are caused by different strains, and a vaccine isn't always available for every one of them.

Why are vaccines so expensive?

The price of vaccines varies by veterinary clinic. When our dog is a puppy, having to vaccinate several times can seem expensive, but afterward we're generally talking about just one or two vaccines a year.

When we decide to share our life with a dog, we need to know it comes with a set of fixed costs. The vet is one of them. Deworming/parasite prevention and vaccines are costs we have to accept as essential. What's more, vaccinating is a clinical procedure that only a veterinarian can carry out — someone who has invested time and money in training and setting up a clinic.

The steady income that vaccines provide for the vet allows other services, like surgeries, to be offered at a more affordable price. Lastly, the cost of treating a dog that catches one of these diseases is far higher than the price of a vaccine, and in many cases doesn't even guarantee a cure.

Do vaccines have side effects?

In the hours after the shot, the animal may experience discomfort, swelling at the injection site, fever, an allergic reaction on the face or back, or a drop in activity and appetite.

• Possible side effects of dog vaccines

Contraindications to vaccination

When a dog already has a disease, parasites, allergies, or any condition that weakens its immune system, vaccinating it may not do any good, since its body won't be able to form the necessary antibodies.

Vaccinating dogs undergoing treatment with immunosuppressive drugs isn't recommended either. In females that are pregnant or reasonably suspected of being pregnant, vaccination is contraindicated, except for herpesvirus or in certain specific situations the vet needs to assess.

Also, puppies will be protected by the antibodies passed on by their mother for about eight weeks. Depending on the case, the vet will decide whether to vaccinate them earlier, so as not to interfere with these antibodies. That's why giving a vaccine is a clinical procedure that's solely the vet's responsibility, and they must examine the animal first.

Bibliography Carlson and Giffin (2002): Manual práctico de veterinaria canina. Madrid: Editorial el Drac. Fariñas, Fernando (2015): Fallos vacunales dependientes del animal: mitos y realidades. Portal Veterinaria, October 21, 2015. Marco de buenas prácticas para el uso de vacunas en animales (2019): http://www.vetresponsable.es/vetresponsable/guias/marco-de-buenas-practicas-para-el-uso-de-vacunas-en-animales_4176_347_4417_0_1_in.html Roura, Xavier (2015): Control de la leptospirosis canina en Europa: ¿Es el momento para un cambio? Portal Veterinaria. January 7, 2015. Simón, Mª Carmen Simón (2017): Cómo se establece un plan vacunal. Ateuves nº 6, pp. 22-26. WSAVA (2016): Guidelines for the Vaccination of Dogs and Cats: https://www.wsava.org/WSAVA/media/PDF_old/2015-WSAVA-Vaccination-Guidelines-Spanish.PDF