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Canine distemper is a contagious, febrile disease of canids and other carnivores caused by Canine Distemper Virus. Canine distemper virus is a member of the Paramyxoviridae family and the morbillivirus genus. The Paramyxoviridae have a helical nucleocapsid surrounded by an envelope which possesses spiked glycoproteins responsible for haemagglutinin, neuraminidase and haemolytic activities. The genome of the Paramyxoviridae is single-stranded, negative-sense RNA which is used as a template for the production of messenger (positive-sense) RNA and further genomic material. Paramyxoviridae are sensitive to heat, dessication and most disinfectants, and so are not resistant in the environment. The Paramyxovididae family is divided to two sub-families, the Paramyxovirinae and the Pneumovirinae. It is within the Paramyxovirinae sub-family that morbilliviruses fall, along with respiroviruses, henipaviruses, rubulaviruses and avulaviruses. As well as canine distemper virus (CDV), the morbilliviruses include rinderpest, peste de petits ruminants, measles, phocine distemper and dolphin distemper.

Canine distemper is a contagious, febrile disease of canids and other carnivores caused by Canine Distemper Virus. Canine distemper virus is a member of the Paramyxoviridae family and the morbillivirus genus. The Paramyxoviridae have a helical nucleocapsid surrounded by an envelope which possesses spiked glycoproteins responsible for haemagglutinin, neuraminidase and haemolytic activities. The genome of the Paramyxoviridae is single-stranded, negative-sense RNA which is used as a template for the production of messenger (positive-sense) RNA and further genomic material. Paramyxoviridae are sensitive to heat, dessication and most disinfectants, and so are not resistant in the environment. The Paramyxovididae family is divided to two sub-families, the Paramyxovirinae and the Pneumovirinae. It is within the Paramyxovirinae sub-family that morbilliviruses fall, along with respiroviruses, henipaviruses, rubulaviruses and avulaviruses. As well as canine distemper virus (CDV), the morbilliviruses include rinderpest, peste de petits ruminants, measles, phocine distemper and dolphin distemper.

      

      

Canine distemper virus is spread by direct and indirect contact via ingestion or inhalation of aerosolised droplets. Initial infection of the nasal cavity, pharynx and lungs is followed by a macrophage-associated viraemia to local lymph nodes where the virus replicates. Within one week, all lymphoid tissue is infected and a secondary viraemia distributes the virus to the surface epithelium of the respiratory, gastrointestinal and urogenital tracts, and later to the CNS. In early infection, a fever of 1-2 days duration and lymphopenia (due to replication in lymphoid tissue) may be the only clinical findings, and further signs depend on both the virus strain and the immune response mounted.

 

Spread is by direct and indirect contact and the mode of infection is by ingestion or inhalation (droplets). Food, water, litter, etc., are readily contaminated with infectious discharges and secretions.

 

 

The virus replicates in the upper respiratory tract, tonsils and bronchial lymph nodes. A macrophage-associated viremia follows, infecting general lymphoid tissue. In the absence of an adequate immune response the virus infects the major systems including the CNS. Virus replication can damage immune cells resulting in immunosuppression.

 

*Multiplies in the bronchial and other lymph nodes, infects [[Monocytes|monocytes]] and dendritic cells

*Respiratory and alimentary tracts, skin and later (1-5 wk. post infection) to the brain

**Severe clinical pneumonia follows secondary infection with [[Bordetella bronchiseptica|''Bordetella bronchiseptica'']]

**Eruptions on the skin including hyperkeratosis of the nose and pads (hardpad)

**[[PNS Repsonses to Injury - Pathology#Segmental Demyelination|Demyelination]] (especially in cerebellum) -> incoordination or muscle tremors -> paralysis and coma or convulsions -> death

**Recovered animals may have persistent or spasmodic chorea

**The severity of the disease may vary; if enough neutralising antibody develops in the early stages, the virus maybe kept restricted largely to the lymph nodes

 

==Signalment==

==Signalment==