The local authority public analyst heading the inquiry said the rat's presence indicated "severe failings somewhere in the food production process".
Some analysts see the inquiry as possibly part of a broader Chinese plan to increase consumption of local infant-milk products.
If the N.S.A. inspector general begins an inquiry, analysts said, that could also signal a new willingness by the agency, under a new administration, to examine its own operations in the eavesdropping program.
Because of the controversy surrounding Tenet's disclosures and the rapid unfolding of events, analysts said the S.E.C. inquiry was not a surprise.
Next week the company will release its second-quarter results and is likely to be quizzed further by shareholders and analysts about the SEC inquiry.
But several former top aides to Mr. Rumsfeld insisted that the purpose of the program was merely to inform and educate, and many of the 63 military analysts interviewed during the inquiry agreed.
And because the abortive patent settlement is also now the subject of a federal criminal inquiry, some analysts raised questions about whether Peter R. Dolan, Bristol-Myers's chief executive, can survive.
The inquiries and analyst's account underscore how e-mail messages, more so than telephone calls, have proved to be a particularly vexing problem for the agency because of technological difficulties in distinguishing between e-mail messages by foreigners and by Americans.
