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Canine Distemper Virus
Clinical Signs


As they say; "an ounce of prevention is worth a pound of cure!"   In the case of Canine Distemper, that ounce may be worth more than a pound, especially since the only direct method of dealing with the Canine Distemper virus itself is by preventing the onset of disease.  This is achieved through preparing the immune system to deal with any challenges from the virus.  On top of vaccination, there are also other ways to help reduce the chances of Canine Distemper exposure/infection/disease.

So how do you prepare an immune system to deal with something that it has never seen before?  You prime it ahead of time with vaccines or maternal antibodies.  Vaccination is the best method of preventing Canine Distemper (Deem et al., 2000).  There has been a decrease in the incidence of Canine Distemper due to widespread vaccination (Nelson and Couto, 2003).  Severe, generalized Distemper is most common in young, non-vaccinated dogs (Nelson and Couto, 2003).  It is the modified live virus vaccines that are said to offer superior protection against Canine Distemper Virus.  The only thing that would provide a stronger immunity to the virus would be surviving natural infection.  Due to the homogeneity of the virus, long term immunity can be possible through vaccination.  It is also possible to have additional protection from Canine Distemper Virus through vaccination against measles (a human virus), due to the relatedness of these two viruses.  Although the immunity from  vaccines (or natural infection) can last for years, periodic boosters are a good idea (Greene, 2006).

As with any vaccination, there is no 100% guarantee that your dog will go without ever getting the disease.  There are certain factors that may reduce the efficacy of vaccination or even make vaccination a bad idea at the time.  A vaccine may not be as protective in situations where the animal is exposed to a more virulent strain of the virus, or if they must deal with a high level of exposure to the virus, which their immune system is not prepared to handle.  If the animal has already been infected prior to vaccination, the vaccine is not going to cure the infection.  During high stress, or when concurrent infection, poor nutrition, or any other factor causing a reduction in the immune system's function, an animal may become more susceptible to infection/disease (Greene, 2006).  The vaccine also does not work alone to determine how well a dog's immunity will be.  The Animal's age, environment, health status and the virus' factors (i.e. virulence, strain etc.) will all contribute to severity of disease.  It must be noted that in puppies that have obtained adequate colostrum, there will be a certain level of maternal antibodies. These maternal antibodies initially protect the puppy but they will interfere with efficacy of vaccines, decreasing future protection.  It is because of this interference that it is necessary to wait until maternal antibody has decreased before giving the first vaccine to a puppy.  Puppy vaccination is followed with a series of booster shots for the first few months of life.  One recommendation is to give the first vaccination at about 6-8 weeks of age, then follow with a booster shot every three weeks until the age of 14 weeks.  A booster shot at one year of age, then every three years, should follow the initial series of vaccination (Nelson and Couto, 2003).   Incomplete vaccination has been implicated in the failure of immunity in some circumstances.  Vaccination with the modified live virus vaccine has also resulted in the occurrence of a meningoencephalitis in dogs with concurrent canine parvovirus infection, therefore vaccination is not indicated in these animals (Greene, 2006) .
 *for vaccines licensed in Canada, please refer to the links page*
So is vaccination the only way to keep Canine Distemper from causing disease?  The answer is no!  There are other approaches that may be utilized in order to reduce the infection pressure.  One way to keep an animal from getting Distemper is to simply keep it away from the virus.  The number one source of  Canine Distemper Virus is infected animals (Greene, 2006).  It is possible for not only sick animals to shed the virus, but also those that are infected and do not show disease (carrier animals).  Animals that have not yet developed clinical signs, or have recovered from the symptoms may also shed virus capable of causing infection/disease in other animals.  So if a dog is definitely infected, or may have been exposed it is a good idea to keep that animal from being in contact with other animals until appropriate diagnostic tests can be run on the animal, or a sufficient quarantine period has elapsed.  If natural Canine Distemper infection does occur, shedding of the virus is possible for 60 to 90 days following the infection.  Animals that are only exhibiting neurological signs of disease are not generally shedding. The good news about shedding of the virus is that Canine Distemper does not survive for an extremely long period of time in the environment (Greene, 2006; Nelson and Couto, 2003)  Disinfection is very useful in reducing the survival of Canine Distemper Virus outside of a host (Greene, 2006).  This virus will survive in exudates from a shedding animal for about 20 min.  One must also be careful to avoid transporting the virus via fomites.  Aerosolization of the virus may also be a potential problem in some situations (Nelson and Couto, 2003).