Canine Distemper: Why Vaccination is So Important
Canine distemper is a very important disease of dogs. That is why it is so critical to vaccinate your pet. Canine Distemper causes high morbidity (a lot of dogs get sick) and high mortality (a lot of dogs will die). Luckily, in countries that have a vaccine available, the incidence of disease and death is rare. This virus can affect all closely related species, not just domesticated dogs. Foxes, wolves, coyotes, raccoons and ferrets are all affected. Large cats (lions, leopards and tigers) can also get distemper.
The symptoms you will see vary based on the age and immune status of your pet. The first signs you will see include an eye discharge that will be watery and/or pussy. You may see lethargy, respiratory (nasal discharge and coughing), gastrointestinal (reduced appetite, vomiting and diarrhea) and central nervous system signs and fever. Be aware that the normal ranges for temperatures are different in dogs than they are in humans. Normal temperatures in dogs are between 100 and 102.5. Late symptoms include seizures, twitching and partial to complete paralysis.
Aerosol droplets are the main route of infection. This means that when a sick dog coughs or sneezes it sends out little droplets that carry the virus. If these droplets are inhaled by another dog, that dog may develop disease. CDV lasts for days in the sunlight and weeks in the cold. It is important to protect your dog not only from other dogs with CDV but also from the wildlife listed above that may also carry CDV.
How does it cause disease? When the virus gets into cells it replicates, which means it makes more and more virus inside that cell. Eventually all the resources and space in the cell are used up, the cell dies as the virus particles are released. Think of the cell as a mini Trojan horse, and all the viral particles are the soldiers, who want to get out. When an animal breathes in the virus from an aerosol droplet, the first place the virus hits is the respiratory tract. So for the first 8-9 days after infection, this is where the virus replicates. You will see respiratory symptoms and fever. The virus then spreads to other parts of the body. If the animal has a strong immune system, it may be able to limit the disease. By 14 days, the virus will have spread to mucosal surfaces (like those in the GI tract) all over the body. CNS signs will appear in dogs with weak immune systems. ½ the dogs that appear clinically ill will develop neurological disease as early as 1 week after the epithelial stages.
Dogs with strong immune systems will have little to no clinical signs (mild cough). Dogs with intermediate immune systems will have chronic persistent encephalitis (neurological signs). Dogs with poor immunity will have acute encephalitis (nasal discharge, pneumonia, and diarrhea.) Central nervous system signs include epileptic seizures, weakness and paralysis. These dogs will also have hyperkeratosis (hard foot pads and hard nose.)
How can you make sure your puppy has a strong immune system? Three of the major factors that influence immunity are age, vaccine status, and concurrent illness. Making sure your puppy is up to date on its vaccines and is treated for any other diseases will help keep their immunity strong. Make sure your puppy stays away from puppy parks (pet stores, puppy classes, doggy daycare, groomers and boarding facilities) until it has been vaccinated. You never know if other people have their pets vaccinated or not. Vaccination works to increase serum antibodies, these antibodies can then bind virus before it infects cells. The virus can’t live outside the cell, so your pup has a greater chance of not developing symptoms. The first vaccination should be at 6 weeks of age, then every 2-4 weeks until the animal is 16 weeks old.
Dogs are most susceptible when they are between 4-6 months of age. This is because at this age the antibodies the puppy received from its mother block the effectiveness of the vaccine, but don’t exist in large enough quantities to protect from viral infection.
As with most viruses, once your dog become ill there is no quick cure. Treatment is mainly supportive, and involves providing fluids to prevent dehydration (from vomiting and diarrhea), antibiotics to prevent secondary infections, and anti-emetics to stop vomiting.
