Introduction
Prior to vaccination distemper virus was the major pathogen of dogs and puppies. Dogs ferrets seals lions and mink are susceptible to the virus.
Pathogenesis
Mortality is variable (average 20%) according to the virulence of the strain; some cases may be subclinical. However CNS involvement often causes >90% mortality.
Stages
Infection of the alveolar macrophages or orpharynx.
Viraemia and virus infection of macrophages and dendritic cells.
Spread to most epithelial tissues and skin.
Opportunistic bacteria cause pyogenic discharges and diarrhoea.
Hyperkeratosis of the pads (hardpad) and nose, skin rash.
Late infection of neurones. Demyelination. Incoordination or muscle tremors which may progress to paralysis and coma or to convulsions.
Death. Recovered animals may have a persistent or spasmodic chorea.