What is the incubation period for Johnes disease?
Sheep generally become infected as young animals, less than one year old, although older animals can become infected. The period between initial infection of Johne’s disease and the onset of clinical signs can be several years. Animals up to 12 months of age, particularly those in the first few months of life, are susceptible to infection but seldom show signs before they are two years old. Clinical cases generally start in animals between three and six years old. The long incubation period means that on infected properties, sheep can be grazed on infected pasture for six(6) to12 months and then sent direct to slaughter without spreading the disease.
