Merck & Co and Schering-Plough have been told to provide yet more information to antitrust regulators in the USA regarding their $41.1 billion proposed merger.

The firms have received a “second request” from the Federal Trade Commission about their planned link-up and the agency is particularly interested in their plans concerning the companies’ animal health businesses. Merck has previously suggested that it could divest its stake in the Merial joint venture with Sanofi-Aventis, while S-P’s thriving animal health business, which had revenues of just under $3 billion last year, could be sold off.

Merck and S-P say that the request was “anticipated” and they intend to “cooperate fully with the FTC to obtain approval of the transaction as expeditiously as possible”. The companies added that they continue to expect the deal, which also requires clearance by the European Commission and other regulators worldwide, to close during the fourth quarter.

Analysts believe that the deal will still go through as the issue of the animal health businesses appears to be the only area that concerns competition agencies. Furthermore the aforementioned units are successful operations likely to attract a number of potential buyers and Sanofi has also expressed an interest in buying Merck’s share of Merial.

Meantime, Merck has launched a $4.25-billion debt offering to help finance the S-P merger. Specifically, the four-part offering includes $1.25 billion of 1.875% notes due 2011, $1.00 billion of 4% notes due 2015, $1.25 billion of 5% notes due 2019 and $750 million of 5.85% notes due 2039.

The move follows a similar strategy for raising funds adopted recently by Roche and Pfizer to help finance their acquisitions of Genentech and Wyeth respectively. Merck added that the proceeds will also be used for general corporate purposes.