Dog Vaccines: Your Questions Answered

The questions:

The Answers:

Q: Why is there a need to vaccinate?

A: The current low incidence of diseases such as distemper is principally due to dog owners having their pets routinely vaccinated. This has helped the canine population as a whole to develop what is known as a 'herd immunity'. Herd immunity describes a type of immunity that occurs when the vaccination of a significant proportion of the population (or herd) provides a level of protection to unprotected individuals. This has the effect of ensuring that because a significant proportion of the population is vaccinated, the disease cannot spread easily.

Vaccination is necessary in order to provide protection against life threatening diseases such as distemper, hepatitis, parvovirus and leptospirosis. Vaccination also can be used to protect against kennel cough due to both Bordetella bronchiseptica and parainfluenza virus infection, which although rarely life-threatening, can cause illness and an uncomfortable cough in unprotected dogs. Vaccination is the only proven method of protecting against these diseases. Apart from perhaps leptospirosis, there is no specific cure for them, and in all cases - including leptospirosis - treatment may not only be unsuccessful but also extremely expensive.

Q: How are vaccines given?

A: Vaccinations against canine distemper, parvovirus, leptospirosis, infectious canine hepatitis and para influenza are given by injection under the skin, usually at the back of the neck.

The vaccination against kennel cough is given by administering a small amount of liquid into the dog’s nostrils. This enables the vaccines to provide local protection in the dog’s nasal passage and airways

Q: Why do boosters have to be given; people don't get boosted, so why do pets?

A: Clinical cases of the diseases that dogs are vaccinated against still occur in the UK. A dog is always at risk of potential exposure to one of them if it goes out or comes into contact with other dogs, or, in the case of leptospirosis, with wild rodents or the areas they frequent. Individual Immunity following vaccination is variable and unlikely to be lifelong. Regular booster vaccination is an effective way of 'topping up' a dog's immunity thereby minimising the risk of disease when challenged by natural infection. Some human vaccines are in fact boosted where there is an increased risk of exposure, for example vaccination against 'flu or polio. Furthermore, in general a higher proportion of the human population is vaccinated, thus affording a greater level of ‘herd immunity’.

Q: Why do vaccines cost so much and why is there so much variation between practices?

A: What is being paid for is full professional consultation in addition to the cost of vaccination. When taking an animal to be vaccinated the vet will not only be administering one or more doses of vaccine but will also perform a thorough health examination. Many vets will also use the opportunity to discuss other aspects of pet healthcare, such as worming, flea control, diet, etc. Variation in the costs of the 'vaccination and consultation' package can occur for a number of reasons such as different practice overheads. Most vets will be only too happy to explain what you will be getting for your money.

Q: I have heard vaccines can cause side effects, is this true?

A: Serious side effects following vaccinations are extremely rare. Although all veterinary vaccines undergo thorough, independent evaluation of their safety, efficacy and quality, it is impossible to guarantee that any product will be safe and effective in every individual case. It must be remembered, though, that the very small risk of a vaccine side effect is greatly outweighed by the benefit of protection against serious disease. This point has been endorsed by the Working Group set up by the government's independent expert Veterinary Products Committee who undertook a thorough review of all UK licensed dog and cat vaccines⁽¹⁾ . They concluded: "Vaccination plays a very valuable role in the prevention and control of major infectious diseases in cats and dogs". Although adverse reactions to vaccination, including lack of efficacy, occasionally occur the working group concluded that the "overall risk/benefit analysis strongly supports their continued use".

Moreover, an independent and scientifically peer reviewed study carried out by the Animal Health Trust at Newmarket has produced the clearest evidence yet that routine vaccination of dogs in the UK does not increase frequency of illness⁽²⁾.

⁽¹⁾ Veterinary Products Committee (VPC) Working Group on Canine and Feline Vaccination; final report to the VPC published by DEFRA, May 2001

⁽²⁾ Vaccination and ill-health in dogs: a lack of temporal association and evidence of equivalence; D S Edwards, W E Henley, E R Ely and J L N Wood, Vaccine Journal, Volume 22/25-26, September 2004.

Q: Homeopathic vaccines, what about them?

A: The main concern most vets have about their use is that there is no proper independent evidence to show that they work in protecting dogs by preventing disease. Indeed, the few properly designed trials that have been carried out by using homeopathic nosodes have shown no evidence of protection. Without evidence of effectiveness, homeopathic nosodes may pose far greater risk to dogs by leaving them susceptible to disease.

Q: What are the different types of vaccines and why are they used?

A: A live vaccine is a vaccine in which the live infectious agent is weakened through chemical or physical processes in order to produce an immune response without causing the severe effects of the disease in the animal that is vaccinated.

A modified live vaccine is one that utilizes an attenuated (weakened) bacteria or virus to elicit an immune response.

A killed vaccine is a vaccine made from an infectious agent that has been inactivated or killed in some way.

Different types of vaccines have been shown to be effective against different infectious agents The type of vaccine used is determined by the vaccine’s ability to induce a beneficial immune response against the infectious agent being vaccinated against. For some infectious agents an adequate immune response can be elicited using killed vaccines, for others live vaccines are needed to establish immunity.

Q: Company literature says that only healthy dogs should be vaccinated; why is this and what are the risks to an unhealthy dog?

A: To get the full benefit of a vaccine it is important that the dog is healthy which is why it is essential that your vet carries out a health examination before vaccinating your pet. Your veterinary surgeon will then be able to assess if your dog is well enough to receive a vaccination or not. When faced with an animal with long-term disease such as heart disease or diabetes, most vets will advise that vaccination should be continued. There is no evidence that such animals fail to respond or are at greater risk of problems.

Q: Do vaccines affect different breeds in different ways?

A: There are no breed-specific contra-indications for any of the vaccines currently on the market. Despite this, some breeders occasionally suggest that one or other of the live vaccine components affects their particular breed. When such reports are investigated the information appears to be purely anecdotal and incapable of substantiation.

Q: Why do all dogs get the same vaccine dose, irrespective of size, or breed?

A: When we give drugs such as antibiotics or wormers, the effect depends on achieving a certain concentration of the active ingredient in the body of the animal and, for this reason the larger body mass, the greater the total amount needed to achieve the correct dose concentration. However, vaccination doesn't work like this, when we give a dose of vaccine what we are doing is giving a sufficient dose to stimulate the body's immune system to generate a protective immune response. The immune system in fact requires the same degree of stimulus irrespective of the body mass or breed, therefore we need to use exactly the same dose of vaccine for a Chihuahua as for a Great Dane!