Canine distemper is caused by canine distemper virus (CDV), a morbillivirus.
Besides dogs, CDV infects several other animal species, but it has not caused disease in domestic cats.
Infection
CDV spreads through direct contact, through the air or by droplets from infected dogs. There are also carriers that show no symptoms.
Puppies aged 3–6 months are most often affected, as the protective antibodies they received from the bitch disappear.
An infected dog sheds the virus in all body secretions for up to 90 days after infection.
Symptoms
In puppies, the central nervous system is affected and mortality is high.
Adult dogs usually only get mild upper respiratory symptoms, fever and reduced appetite, which are easily overlooked, so adult dogs can be hidden carriers.
In affected dogs, the first symptoms are usually eye inflammation and a dry cough that worsens into a wet cough with nasal discharge. Pneumonia with a high fever (over 40°C) then develops. The dog becomes generally unwell and loses its appetite. Diarrhoea and vomiting are sometimes seen.
Some dogs die suddenly, but good supportive treatment often leads to a good recovery.
About 1–3 weeks after recovery from general or hidden illness, viral inflammation of the brain and its membranes is sometimes seen. The neurological damage usually shows as neck stiffness, movement disorders, paralysis, involuntary muscle twitching and seizures. The neurological symptoms usually get worse, despite a period of temporary improvement.
Sometimes the eyes are also affected, with nerve damage causing blindness and dilated pupils. Some dogs develop degeneration of the retinas with a characteristic scarring that an eye specialist can see.
Puppies that survive may develop hardening of the nose and paw pads about 3–6 weeks after infection.
When puppies are infected before their adult teeth come through, the permanent teeth can also be affected, with poor or missing enamel.
If a pregnant bitch falls ill, the foetuses can be infected via the uterus. Abortion, stillborn puppies or weak newborn puppies are commonly seen.
Hygiene
The virus does not tolerate heat and sunlight very well, but it survives for several weeks in colder surroundings.
The virus is sensitive to grease-dissolving detergents; clean with these before using a disinfectant.
Prevention
Guldveterinären vaccinates against canine distemper with Nobivac DHPPi, puppies at 8 and 12 weeks of age and at 1 year of age, and after that every three years.
Read more about canine distemper on the website of the Swedish Veterinary Agency (SVA), in Swedish.
