A necropsy technique for cattle to eliminate contamination of lymph nodes by mycobacteria.

A field necropsy technique for cattle is described which avoids contamination by environmental mycobacteria of tissues intended for bacteriological examination. Settling the dust by hosing on and around the carcase, using sterile instruments for the collection of each tissue, excising lymph nodes without incising the capsule and submitting the nodes to the laboratory intact in saturated tetraborate solution resulted in uncontaminated samples even under adverse field conditions. The procedure is recommended for future investigations into the role of mycobacteria other than Mycobacterium bovis in the sensitisation of cattle to the intradermal test for tuberculosis.