Most dog owners are very good at bringing their pets in every year for their annual ‘booster’ vaccinations. But not many people know how these vaccinations work, or even what diseases we are vaccinating against. Hopefully, we can clarify all that here for you!
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What diseases do we vaccinate dogs against?
In the UK we routinely vaccinate against the following diseases in dogs –
Distemper
Distemper is a virus that attacks various organs in the body leading to symptoms such as high temperature, runny eyes and nose, lethargy, diarrhoea, thickening of the paw pads and nose, tremors and seizures. This disease can be fatal. Thanks to vaccination, this is less commonly diagnosed in the UK these days, but unvaccinated dogs are still at risk.
Infectious Hepatitis (canine adenovirus)
Infectious hepatitis can be caught by direct dog-to-dog transmission, or from being in an area where an unvaccinated dog has been. This virus affects not only the liver but also other major organs like the kidneys, heart and lungs. Mild cases can have vomiting, diarrhoea and lethargy but severely affected animals could develop liver failure causing pale/yellow gums, fever, seizures and sudden death.
Canine Parvovirus
Many people have heard of this one, probably because we still get frequent disease outbreaks. Affected animals suffer from damage to the lining of their guts causing bloody diarrhoea and vomiting, dehydration and collapse. It also weakens the animal’s immune system. Parvovirus can last for a long time in the environment and is highly contagious.
Leptospirosis
This disease is caused by bacteria that primarily affect the kidneys and liver. It is not only spread by infected dogs, but also by mice, rats, and cows, and is fatal in many cases. It can also be found in infected water, such as ditches or stagnant ponds. Leptospirosis is zoonotic, which means it can make people seriously ill, making vaccination important from a human health perspective too.
Kennel Cough
Kennel cough can be protected against through a separate vaccination from your pet’s normal booster injection. This disease usually causes a retching/hacking cough which can linger for several days. While not as serious as some of the other diseases mentioned, some severely affected dogs may develop fever, lethargy and reduced appetite. Your pet is more likely to catch this disease if they mix with other dogs on walks, with dog sitters/kennels or at training classes.
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How do vaccinations work?
When a vaccination is administered, a small amount of the disease-causing agent is given to your dog. The vaccine may be a “modified live” (also known as “live attenuated”) one, in which case a modified and weakened version of the virus or bacterium is used. This is still able to stimulate the natural immune response, but is too weakened to cause illness in a healthy dog. Vaccines for parvovirus and distemper, for example, are modified live vaccines, and can often give the strongest immune responses (although the live attenuated kennel cough vaccine is an exception). Other vaccines are “killed” or “inactivated”, where the pathogen is dead and can never cause disease, but is presented along with adjuvants to trigger an immune response.
What do vaccines do to the dog’s immune system?
They stimulate a normal immune response – called specific (or adaptive) immunity. It is not present from birth but develops over time as the dog becomes exposed to different antigens (foreign molecules). Your dog’s immune system learns the best way to deal with each antigen, building a type of ‘memory’.
This means if the dog encounters these antigens again in the future, their immune system can mount a rapid response and effective response against it. Specific immunity involves white blood cells known as a lymphocyte (B cells and T cells), antibodies, antigen-presenting cells, and cytokines. This response is exactly the same whether the immune system is presented with the actual disease-causing virus or bacterium, or a vaccine. The main difference is that the vaccine is much, much safer!
This type of immunity works alongside your dog’s two other immune mechanisms, non-specific (innate) immunity and physical barriers (e.g. the skin, gut acids, and respiratory tract linings). However, specific immunity tends to be the most effective against the diseases we have listed above, so harnessing this through vaccinations is the best way of protecting your pet.
Are there any risks associated with vaccinations?
Sadly, there has been a lot of unfairly negative press about vaccinations in recent years. All of the vaccinations that vets use have undergone rigorous safety tests, and we use them without issues on thousands of pets each year.
Vaccination programmes have worked so well that some of the diseases we protect dogs against are now rarely seen. However, they are not gone altogether and if we all stopped vaccinating our dogs, we would soon see a resurgence in sick animals. These diseases are fatal, so the benefits of vaccination far outweigh any small risks of vaccine side effects.
While vaccination side effects are uncommon, you may see the following –
- Lethargy
- Reduce appetite
- Fever
- Mild swelling at the injection site (which may last a few weeks)
Even less common side effects could include –
- Diarrhoea
- Vomiting
- Limping
- Itchiness
In extremely rare circumstances a severe allergic reaction could occur (anaphylactic shock). This usually occurs soon after vaccine administration, with swelling, breathing difficulty, seizures and collapse occurring.
Speak to your vet if you have any concerns about vaccination side effects.
Are there alternatives to vaccination?
Some pet owners may want to perform titre testing on their dogs. This blood test is a way to check whether your dog has formed an appropriate immune response to their previous vaccinations.
This information can reassure us about whether immunocompromised dogs have formed immunity, can help us to decide whether any further vaccinations are needed and allows owners to make more informed decisions about their dog’s ongoing preventative care.
Results and vaccination plans should be reviewed with your vet to ensure your dog has adequate protection. You should also bear in mind that while titre testing is helpful for some core diseases, your dog will still need their annual vaccinations against others. There are no reliable titre tests for leptospirosis or kennel cough, so your dog should continue to receive boosters for these.
Summary
Vaccinations work by stimulating your dog’s immune system without causing them to be unwell. This means that if your dog encounters the real illness at a later date, they will already have a ‘memory’ and a rapid immune response occurs. This mechanism keeps your pet well in the face of some potentially fatal diseases. If you have any concerns about vaccinations or how they work, then speak to your vet for advice.
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