The classic lesion associated with tuberculosis is the tubercle, a tumor-like mass that can grow to great size. In primates and cattle, the primary lesion is usually in the lungs. In deer and poultry, the most common site is the abdomen. Lesions and involved lymph nodes become filled with white, creamy, caseous material, often with mineralization. TB lesions may become walled off with thick fibrous tissue, slowing down the spread of the disease.
Clinical findings depend on the extent and location of the lesions.
Tuberculosis is most commonly a chronic disease leading to emaciation, weakness and difficulty breathing and coughing when the lungs are affected. Animals may show no signs for long periods of time, particularly when lesions have been walled off. Deer and llamas are commonly TB tested. In deer, the injection site is the midcervical area. In llamas, the site is the hairless axillary area.