Canine Distemper

What is canine distemper?

Canine distemper is a highly contagious and sometimes fatal infection caused by the canine distemper virus (CDV) that affects dogs and wild animals (including coyotes, foxes, skunks, raccoons, and pinnipeds, among others) worldwide. Puppies less than 20 weeks of age are especially susceptible to infection, which can affect the respiratory, gastrointestinal, skin, immune, and nervous systems. Cats are generally not affected by CDV, but ferrets are highly susceptible.

The virus is shed in bodily secretions from infected animals and can be spread by direct contact or exposure to respiratory droplets. It can be transmitted through contaminated hands, shoes, instruments, equipment, and other surfaces. Animals with subclinical or mild infections can shed the virus.

What are the clinical signs of canine distemper?

Clinical signs of canine distemper are highly variable and depend on the strain of the virus, the age of the host, and any concurrent infections. Initial signs usually consist of discharge from the nose and eyes, depression, and loss of appetite. Secondary bacterial infections may occur in infected animals due to a weakening of the immune system. Additional signs may include fever, low energy, coughing, difficulty breathing, pneumonia, loss of appetite, vomiting, diarrhea, vision impairment, skin rash, and behavioral changes. Neurologic signs, such as circling, seizures, paralysis, and loss of coordination, develop in up to 30% of affected dogs. Some infected dogs show no clinical signs (subclinical), but can shed infectious virus for weeks or months.

How is canine distemper diagnosed?

Diagnosis of canine distemper is based on progression of clinical signs combined with laboratory testing and health history. Reverse transcription polymerase chain reaction (RT-PCR) can detect viral RNA in respiratory secretions, as well as cerebrospinal fluid, feces, and urine. Immunofluorescence assay may be used during the early stages of the disease. Serology testing can be a good indicator of distemper infection in previously unvaccinated animals, but can provide false positive results in animals that have been recently (within 3 weeks) vaccinated.

Respiratory signs can closely mimic those of canine parvovirus enteritis or infectious upper respiratory disease (“kennel cough”), so a combination of laboratory tests may be required to arrive at a diagnosis of distemper.

How is canine distemper treated?

Treatment for canine distemper is largely supportive and may include fluid administration, nutritional support and antibiotics. Anti-seizure medications and steroids (such as dexamethasone) may be required in some cases. There are currently no anti-viral medications available for CDV.

What is the prognosis for canine distemper?

Dogs with neurological signs that are progressively worsening have a poor prognosis for recovery and may be euthanized. Neurological damage may be permanent in those who survive. With supportive care, dogs with gastrointestinal or respiratory disease have a fair prognosis for long-term recovery. Survivors may experience thickening of the skin on the paw pads and nose and damage to the teeth enamel. Dogs with mild signs or who never show clinical signs usually recover fully.

How can canine distemper be prevented?

The best way to prevent canine distemper is to vaccinate your dog(s) beginning at six to eight weeks of age, with revaccination every three to four weeks until 16-20 weeks of age. The canine distemper vaccine is recommended for dogs 4-6 weeks of age and older. Dogs that are older than 16 weeks of age should receive two doses of vaccine three to four weeks apart and a revaccination at one year.  Revaccination is recommended every three years from then on. Dogs that recover from natural infection have lifelong immunity to CDV.  However, revaccination every three years is still recommended in dogs who have recovered due to prevention of pathogens in the combination vaccine (parvovirus, adenovirus and parainfluenza).

The virus is short-lived (<1 day) at room temperature and can be inactivated by heat and many common disinfectants. Routine cleaning and disinfection, as well as avoiding contact between infected dogs can prevent the spread of CDV. For animals living in populations such as animal shelters and breeding facilities, avoiding crowding and using appropriate biosecurity between puppies and other naïve animals, along with isolating sick animals, is critical.

For more information

UC Davis Koret Shelter Medicine Program - Canine Distemper (CDV)

UC Davis School of Veterinary Medicine Animal Health Topics - Vaccination Guidelines for Dogs and Cats

Canine Distemper Virus Infection, in Canine and Feline Infectious Diseases (2014)

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