What are lesions?

A description of the term "lesions" as it applies to Tuberculosis (TB) reactor animals.

The term “lesion” means the damage, injury or change in the function or structure of a part of the body caused by a disease or injury. In the case of TB, lesions are most common in the lymph nodes of the head and chest and in the lungs. They may also occur in the gut and at other sites. If lesions can be seen with the naked eye they are called “visible” lesions. Sometimes lesions may be present that are too small to be visible on the first examination.

Occasionally we find an animal that has TB lesions throughout its body and such an animal may also show signs of disease while it is still alive.  Such cattle are rarely seen nowadays because of yearly testing.