The idea of vaccinating dogs at one year of age and then every three years after that was first proposed in 1978, and was based then on a general understanding of immunity. Since then, more evidence has been gathered to prove that vaccines for the core canine diseases are not only effective, but are also very long-lived. In this blog, we will look at the four core diseases and their vaccines. It is important to remember that these four diseases are all caused by viruses; viruses do not respond to antibiotics, which means dogs that are infected with these viruses can only receive supportive care that helps control the symptoms of the disease until the dog recovers.
This highly contagious disease is an intestinal virus that can cause acute vomiting, diarrhea, dehydration, and death, particularly in young puppies under 6 months of age. In very young puppies, it can also attack the heart, causing inflammation of the heart muscle that can result in permanent damage. Certain breeds such as Rottweilers, American Pit Bull Terriers, Dobermans, and German Shepherds seem to show an increased susceptibility to parvovirus. Because it is so widespread, nearly all dogs risk exposure to this potentially deadly disease, which has a mortality rate (death rate) of 16-48% (depending on the strain, as there are multiple strains of parvo).
The vaccine for canine parvovirus is very effective, particularly if administered at the proper time. The CPV-2 vaccine currently offers cross-protection between the different strains of the virus. According to Dr. Ronald Schultz, one of the leading veterinarian researchers studying canine vaccination and immunity, the minimum duration of immunity for the CPV vaccine is 7 years by challenge. This means that properly-timed vaccinations can provide lifelong immunity in most dogs.
Distemper is also highly contagious and can be easily transferred among most Canid species (dogs, foxes, wolves). Its effects are systemic, causing fever, respiratory problems, gastrointestinal problems, and even encephalitis. Distemper is most known for its complicated neurological problems like seizures and paralysis, many of which remain permanently even after the dog recovers. Distemper’s mortality rate is approximately 50%, greater than that of canine parvovirus. In puppies, this mortality rate can be as high as 80%.
Fortunately, the vaccine for canine distemper is very effective. The duration of immunity for distemper vaccines is a minimum of 5-7 years by challenge (depending on the distemper strain) and a minimum of 9-15 years by serology. Properly-timed vaccinations for distemper can also provide lifelong immunity in most dogs.
Adenovirus, also known as hepatitis, is a contagious viral disease that afflicts the liver and other vital organs. Its expression varies widely, presenting only as a mild fever and lethargy in some dogs, while causing liver failure and death within hours in others. Adenovirus is found worldwide, and can also be found in other canids like foxes, coyotes, and wolves. There are two variations of this virus, CAV-1 and CAV-2. In dogs, CAV-2 can also cause respiratory disease.
The vaccine for canine adenovirus typically uses the CAV-2 strain, which also provides cross-protection against the CAV-1 strain. Like the vaccines for parvovirus and distemper, the CAV-2 vaccine is very effective at preventing the disease, and has a long duration of immunity. The duration of immunity for CAV-2 is a minimum of 7 years by challenge, and 9 years by serology.
Rabies is a disease that strikes terror in the hearts of people, regardless of whether they have pets. Rabies is a contagious viral disease that is spread through contact with the saliva of an infected animal, and is found in both domestic and wild animals, particularly foxes, bats, raccoon, and skunks. Rabies is almost always fatal, attacking the central nervous system with a vengeance. Because rabies can be readily transferred to humans through a bite of an infected animal (or through contact with its saliva), this is the only vaccine that is mandatory for all dogs. Rabies infections in domestic dogs that live among vaccinated populations are very rare.
The rabies vaccine is both effective and long-lived, and overuse of this vaccine has been implicated in several severe vaccine reactions. The minimum duration of immunity of the rabies vaccine is 3 years by challenge, and 7 years by serology. The Rabies Challenge Fund is currently working to extend the interval of vaccination to every 5 years, and then to every 7 years.
Next blog we will discuss the current vaccination protocols recommended by immunology experts like Dr. Jean Dodds and Dr. Ronald Schultz, and explain what is meant by “properly-timed vaccinations”.