If an abscess is found in the carcase or in any organ of any swine or if a Meat Inspector or OVS has reason to suspect the presence of any such abscess, he shall require the carcase to be split through the spinal column if it has not already been so split and shall examine in detail such of the following lymph nodes as he has not already so examined: superficial, inguinal, supramammary, cervical, prepectoral, prescapular, presternal, sublumbar, iliac, precrural and, if he considers it necessary, the popliteal.