Canis ISSN: 2398-2942

Canine distemper virus

Synonym(s): CDV; Canine morbillivirus; Paramyxo virus

Contributor(s): Melissa Kennedy




  • Family: Paramyxoviridae.
  • Subfamily: Paramyxovirinae.
  • Genus: Morbillivirus.

Active Forms

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Clinical Effects



  • The dog is the main reservoir.
  • Infects epithelial cells, mainly of the respiratory tract and bladder, and lymphoid tissues.


  • RNA virus, replicates in cytoplasm of host cells.
  • After aerosol infection, replicates in bronchial lymph nodes and tonsils.
  • Leukocyte-associated viremia follows.
  • Widespread epithelial invasion and replication then occurs, followed by CNS infection.


  • Droplet or direct contact.
  • Shed in all body secretions (particularly respiratory).
  • Wildlife (raccoons, skunks, wild canids) may be a source of the virus. Virus is fatal in ferrets.

Pathological effects

  • Mortality depends on the immune status of the infected animal.
  • Produces a long-lasting immunity in animals that recover.
  • Acute distemper causes immune depression; depletion of lymphocyte (both T and B) producing areas in lymphoid tissue is seen.
  • Virus usually enters via respiratory tract.
  • First found in bronchial lymph nodes and tonsils.
  • Viremia causes spread to alimentary tract, lymphatic system, urogenital tract, conjunctivae and foot pads. The virus targets mononuclear white blood cells as well as epithelia of many tissues.
  • Later may appear in meningeal macrophages and neurons.
  • May cause diffuse demyelinating encephalomyelitis.
    • Encephalitis in acute phase of disease due to virus infection of neurons.
    • Encephalitis in post-acute phase due in large part to inflammatory response incited by the virus.

Clinical signs

  • Incubation period of 3-5 days.
  • May be inapparent or mild. One of the causes of 'kennel cough' Acute infectious tracheobronchitis.
  • Most commonly, diarrhea, respiratory disease, fever, catarrhal ocular or nasal discharges, hyperkeratosis of foot pads and central nervous system (CNS) signs.
  • CNS signs seen 1-3 weeks following recovery from generalized disease.
  • Old dog encephalitis Old dog encephalitis thought to be associated with the virus, but may not be a recent history of generalized distemper.
  • Distemper mortality rate depends on immunity; highest in puppies.
  • Strains vary in virulence; some strains are more immunosuppressive and/or neurotropic than others.
  • In approximately a third of neurological cases there is no history of of respiratory disease.

Other Host Effects

  • Produces a large range of clinical signs from very severe to no visible disease.



  • Modified live vaccines Therapeutics: immunological preparation available and routinely used.
  • Modified live vaccines induce a higher antibody titer and longer duration of immunity than inactivated vaccines. Latter are not available. Recombinant vaccines expressing the surface protein of CDV is available.
  • Vaccination is the best means of controlling distemper.
  • Maternal immunity interferes with vaccination of puppies.
  • Measles vaccine can be used to overcome this if early protection is necessary - rarely used.
  • Imperative that affected dogs be isolated. Virus shedding may occur for seceral weeks.
  • The virus is easily inactivated by detergents, soaps, quarternary ammonium disinfectants.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Beineke A, Puff C, Seehusen F et al (2009) Pathogenesis and immunopathology of systemic and nervous canine distemper. Vet Immunol Immunopathol 127 (1-2), 1-18 PubMed.
  • Saito T B, Alfieri A A, Wosiacki S R et al (2006) Detection of canine distemper virus by reverse transcriptase-polymerase chain reaction in the urine of dogs with clinical signs of distemper encephalitis. Res Vet Sci 80 (1), 116-119 PubMed.
  • Kock R, Chalmers W S, Mwanzia J et al (1998) Canine distemper antibodies in lions of the Masai Mara. Vet Rec 142 (24), 662-665 PubMed.
  • Waner T, Naveh A, Ben-Meir N S et al (1998) Assessment of the immunization response to canine distemper virus vaccination in puppies using a clinic-based enzyme-linked immunosorbent assay. Vet J 155 (2), 171-175 PubMed.
  • Ek-Kommonen C, Sihvonen L, Pekkanen K et al (1997) Outbreak of canine distemper in vaccinated dogs in Finland. Vet Rec 141 (15), 380-383 PubMed.
  • Stettler M, Beck K, Wagner A et al (1997) Determinants of persistence in canine distemper viruses. Vet Microbiol 51 (1), 83-93 PubMed.