Australian Pesticides and Veterinary Medicine Authority

"No one can earn a million dollars honestly"
- William Jennings Bryan

Position Statement - Vaccination Protocols For Dogs And Cats

21 January 2010
Revised 25 January 2010

Introduction

Vaccination plays an important role in maintaining the health and well-being of animals.  The introduction of modified live vaccines has greatly reduced the incidence of several canine and feline diseases that are often fatal.  Vaccines that protect animals from severe, life-threatening diseases that have world-wide distribution are generally referred to as core vaccines.  Non-core vaccines are required by only those animals that are at risk from those specific diseases, due to their geographic location, local environment or lifestyle.

 

Core and non-core vaccines in Australia

	Dogs	Cats
Core vaccines protect against	Canine distemper virus Canine adenovirus Canine parvovirus	Feline parvovirus (= feline enteritis, feline panleucopaenia) Feline calicivirus Feline herpesvirus
Non-core vaccines protect against	Canine parainfluenza virus Bordetella bronchiseptica Leptospira interrogans	Feline leukaemia virus Chlamydophila psittaci Feline immunodeficiency virus

Current vaccination programs using core vaccines

Vaccination regimes for dogs and cats have developed from years of research and practical experience by veterinarians in industry and in practice.

Current vaccination programs for dogs and cats recognise that most pups and kittens are protected by maternally derived antibodies (MDA) up to about 8 to 12 weeks of age.  For strong immunity it is important that the animal receives at least two fully effective vaccinations.  MDA can interfere with vaccination, but it is advisable to vaccinate young animals as soon as MDA levels decline.  Because the decline in the level of MDA varies between animals, three initial vaccinations are generally recommended, timed to ensure that the animal is fully protected.

A typical puppy/kitten program consists of an initial vaccination at 6-9 weeks of age, a second vaccination 3-4 weeks later, and a third vaccination given at 14-16 weeks or even older.  A 12-month booster follows the primary vaccination course to ensure ongoing immunity.

Subsequent revaccinations are given at intervals of 12 months, or longer if this is consistent with the veterinarian’s recommendations and the owner’s wishes.  There are several registered products on the market that have been formulated specifically as longer-term vaccines and proven to provide at least 3 years protection.  Apart from these, all other dog vaccines, and all cat vaccines, have been registered with data that support only a 12-month vaccination interval.

Matters of concern in regard to re-vaccination intervals

There is some concern amongst members of the public in Australia and overseas that there is a small but significant risk to the animal whenever a vaccine is administered, and therefore the number of vaccinations administered should be minimised, based on a risk/benefit analysis for each individual animal.  Although annual vaccination has been common practice in Australia and elsewhere, the international veterinary community is increasingly supporting the position that core vaccines should not be given more often than every 3 years, after the initial course, unless local factors dictate otherwise.

Regulation of veterinary vaccines in Australia

Before a vaccine for use in animals can be sold in Australia, it must be registered by APVMA.  To register a vaccine, APVMA must be satisfied that it will be safe and effective.  The APVMA also approves a label that has instructions on how the vaccine should be given to the animal.

The APVMA assesses a comprehensive data package that is provided with the application to register a vaccine.  Those data include duration of immunity (DOI) studies that are used to determine the recommended revaccination interval.  The objective of these studies is to demonstrate efficacy under the study conditions over a defined period.  These studies are conducted on healthy animals from a restricted genetic background, which are isolated from other animals and challenged using a single dose of the relevant pathogen in a controlled research environment.   

The DOI data submitted to the APVMA for assessment to register a vaccine indicate a minimum DOI in the group of animals involved in the study and in the controlled study environment; they only provide a guide to the duration of protective immunity, as the data from these studies must be extrapolated to a heterogeneous population that is exposed to varying levels of challenge under varying environmental conditions.

Ideally, the optimum re-vaccination interval for any vaccine should be based on high quality epidemiological data – however, such data can only be obtained through broad-scale scientific studies in the field and are not readily available for veterinary vaccines.  For most dog and cat vaccines currently registered in Australia, the DOI studies only support 12-month revaccination intervals. 

The recommended revaccination interval specified on the approved label is based on the data that the APVMA has, at the time of registration, on the minimum duration of immunity for that vaccine.  For a longer revaccination interval to be specified on the label, the registrant must present data from DOI studies that confirm that the vaccine is effective for that longer period.

Regulating the use of veterinary medicines is a matter for each State and Territory; the APVMA has no regulatory authority over use of veterinary chemicals.

The APVMA’s position on re-vaccination intervals

The APVMA notes that

• Re-vaccination has become coupled to a pet’s regular check-up and is an expectation of many pet owners;  at the pet’s regular check-up, veterinarians should provide pet owners with pertinent, up-to-date information on vaccination best practice to assist in a joint decision as to whether and when to re-vaccinate their pet.
• There is a growing body of literature on the duration of immunity of modified live vaccines that are used in dogs and cats.
• The incidence of adverse experiences associated with dog and cat vaccines reported to the APVMA’s Adverse Experience Reporting Program (AERP) is low: less than 1 in 10,000 doses.  The incidence of more serious reactions such as anaphylaxis is very low, and appears to be similar for initial vaccinations and revaccination, which is also true for human vaccines.
• the Australian Veterinary Association (AVA) recently (June 2009) released an updated policy and guidelines on vaccination of dogs and cats which notes that

The Australian Veterinary Association (AVA) believes that in most cases, core vaccines need not be administered any more frequently than triennially and that even less frequent vaccination may be considered appropriate if an individual animal’s circumstances warrant it. However, local factors may dictate more frequent vaccination scheduling.

and highlights the importance of informed consent by pet owners.  The APVMA supports the AVA’s vaccination policy.

• The AVA’s policy refers to the World Small Animal Veterinary Association’s Guidelines for the Vaccination of Dogs and Cats, which state that

Vaccines should not be given needlessly.  Core vaccines should not be given any more frequently than every three years after the 12-month booster injection following the puppy/kitten series.

In formulating a vaccination regimen for an individual animal, the veterinarian should consider many factors including knowledge of the canine/feline immune system, the vaccination history of the animal, its age, breed and health status, disease prevalence in the local area, likely exposure of the animal to other animals, including stray or feral animals, current best practice, contemporary guidelines and published veterinary literature.

The APVMA acknowledges that in some unusual circumstances, such as communities with high prevalence of infection and incomplete vaccination records, annual revaccinations may be advisable - however, the aim should be to ensure that all susceptible animals are vaccinated, rather than that already well-immunised animals are re-vaccinated.  The APVMA does not support the retention of label statements that direct or imply a universal need for life-long annual revaccinations with core vaccines.  The APVMA supports the AVA's vaccination policy and is of the view that product labels should be amended to align with that policy.  The APVMA is working with vaccine registrants with a view to updating labels.

The decision on whether and when to re-vaccinate

It is important that veterinarians tailor vaccination regimens to suit the needs of each animal under their care, and discuss alternatives with their client.

State and Territory legislation that controls use of veterinary medicines allows registered veterinarians to use veterinary medicines “off-label” in dogs and cats.  Veterinarians may therefore use vaccines at whatever interval they (and the client) determine is best for each particular animal.  Veterinarians and pet owners are under no obligation to follow revaccination intervals recommended on vaccine labels.

Ultimately the decision on whether and when to re-vaccinate is made based on an informed risk/benefit assessment carried out by the veterinarian and the owner.  Although this is not a matter over which the APVMA has any regulatory control, the APVMA considers that the veterinarian and the client should consider both the severity of any reaction to a vaccine and the seriousness of the target disease that is being vaccinated against, in making a decision on whether and when to re-vaccinate.

Many factors influence the effectiveness of vaccination and the need for re-vaccination.  As mentioned above, these include knowledge of the canine/feline immune system, the vaccination history of the animal, its age, breed and health status, disease prevalence in the local area, likely exposure of the animal to other animals, including stray or feral animals, current best practice, contemporary guidelines and published veterinary literature.  The vaccination program for an individual animal should be determined within a veterinarian-client-patient relationship, taking all these factors into account.

Testing as an alternative to re-vaccination

Antibody titre testing, to determine if an animal needs re-vaccination, is available for canine distemper virus, adenovirus and parvovirus; and for feline parvovirus, calicivirus, and herpesvirus.  Titre testing is not helpful with diseases where there is poor correlation between the antibody titre and immunity, such as those caused by Bordetella bronchiseptica and canine parainfluenza virus.  Owners should seek veterinary advice when deciding between serology and re-vaccination.