Vaccination - my view
A brief search on social media sites such as Twitter and Facebook immediately demonstrates how emotive the subject of vaccination can be. All sorts of conspiracy theories in the field of human medicine have gained widespread publicity as well as discredited research findings which have led to a reduction in the take up of vaccines. As a result, serious diseases like measles have started to reoccur in parts of the world. This is tragic, especially when large populations of children in some countries do not have access to routine childhood vaccinations.
In veterinary medicine, vaccination against common infectious diseases has greatly improved the health and well being of dogs and cats. Diseases such as canine distemper virus (CDV) and infectious canine hepatitis (ICH) are rarely seen nowadays. I frequently saw cases of CDV when I was a newly qualified vet. Often fatal, it causes very unpleasant symptoms including irreversible damage to the nervous system. In the early 1980s, canine parvo virus (CPV) became endemic throughout the world. Cases of CPV are still seen regularly especially when there are populations of unvaccinated dogs. Despite great advances in veterinary medicine over the last few decades, CPV is still often fatal. For a dog to have any chance of survival, intensive care in a hospital setting is required. CPV is highly infectious and the virus can contaminate premises (e.g pet shops and kennels) for a long time. All puppy vaccination courses contain CDV, ICH and CPV. 1 or 2 doses are required depending on the age of the puppy and the make of the vaccine. A full booster containing all three components is usually given when the dog is just over a year old.
Leptospirosis is a disease which can affect humans, wildlife , farm animals and domestic pets. It is thought to be very widespread in wild rodents such as rats. Leptospirosis can cause abortion in cattle. Dogs are very susceptible to this disease which can affect the liver and kidneys and can result in death or permanent organ damage. The disease is a zoonosis which means it can be transmitted from animals to humans (and occasionally from humans to animals). An infected dog would pose a serious risk to any in-contact humans. There are many different strains of Leptospira (a bacterium) which affect different species of animals and humans. The two commonest strains in dogs (L. Canicola and L.Icterohaemorrhagiae) have been recognised for decades and have been included in puppy vaccination programmes for over fifty years. More recently, two additional strains which can affect dogs, have been identified and are now included in some dog vaccines. These vaccines are often known as L4 (four strains of leptospira) and form part of the primary vaccination courses. It is difficult to quantify the risk to an individual dog from leptospirosis as rats are pretty much ubiquitous in rural areas especially. A dog that loves to swim in rivers and other water courses would be at very high risk of contracting the disease.
Kennel cough or infectious bronchitis can be caused by several different viruses and one bacteria (Bordetella). There is a vaccine available to protect against bordetella and one of the viruses which prevents about 80% of cases.
In the UK, vaccination against Rabies is not routinely performed unless the dog is travelling abroad. Rabies vaccination of dogs is a vital method of protecting humans from this disease in countries such as India where it is endemic in animals.
Like all drugs, any vaccine can potentially cause an allergic or adverse reaction. If a vet suspects an adverse reaction associated with a vaccine, he or she will notify the manufacturer and the veterinary medicines directorate (VMD) using an online system. The drug company will record the details and may investigate the case if it is indicated. It is very difficult to be absolutely sure that there is a definite link between a vaccine and an adverse reaction. Sometimes an animal might receive flea and worm treatments at the same time as a vaccine and will be vaccinated against three or four diseases each time. Since its introduction in 2013, the L4 vaccine has received a lot of adverse publicity on social media. Accounts of dogs suffering from seizures, “swollen glands” and paralysis are common. These accounts are anecdotal and impossible to evaluate scientifically. One of the manufacturers of an L4 vaccine reports a rate of reported reactions of 0.064% or in other words for every 10,000 doses administered six adverse reactions have been reported. There will be instances where adverse reactions are not reported but the overall message is that the risk of vaccination is far outweighed by the risk of contracting the disease. It also should be stressed that, as stated above, leptospirosis is a serious disease and while it can be treated with antibiotics if caught early it can be fatal in some cases and poses a genuine risk to human health.
The fear of adverse reactions to vaccination both in human medicine and in animals may have serious repercussions. The publicity about L4 is now causing a reduction in the take up of vaccination against other diseases too. If this happens to a large enough extent, we will see a resurgence of CPV and even CDV.
Autoimmune diseases such as immune meditated haemolytic anaemia (IMHA) have been linked to the administration of vaccines although not specifically L4. These links have not been proved but it is often recommended that dogs which have recovered from IMHA and other similar conditions do not receive any further vaccines. In cases like this or where an owner is adamant about not vaccinating their pet “titre testing” can be carried out. This measures the levels of antibody to each disease and gives an indication whether the dog is immune or not. Currently, there is no titre test for leptospirosis. If a dog can be shown to be immune, a vaccine is not necessary and the test can be repeated annually until the immunity wanes.
Social media reports about the risks of vaccination often state that vets advocate regular vaccination as a money-making exercise. Most vets are very careful to keep their own pets’ vaccinations up to date and I think I speak for most of my profession when I say that we would never advocate a treatment or preventive if we weren’t prepared to use it in our own animals. I believe that the majority of vets regard the health of both animals and humans as a priority and vaccination programmes in both domestic and farm animals is a vital part of this.
Visiting the veterinary practice for an annual booster injection gives the vet and the owner a chance to discuss preventive health care and to identify problems such as dental disease at an early stage. The loss of this annual appointment, if vaccination is not carried out, could be detrimental to the long term health of the dog.