Pfizer ( PFE) may have to shed some of its animal-health business in order to gain antitrust clearance for its planned purchase of Wyeth ( WYE), Pfizer's chief financial officer said, a published report says. The Wall Street Journal reports Chief Financial Officer Frank D'Amelio told investors at a conference, however, that potential asset sales probably would be immaterial, or less than 10% of the company's combined animal-health revenue, which he estimated at roughly $4 billion. Total pro forma revenue for the combined companies was $71 billion in 2008, Pfizer has disclosed. Pfizer announced in January a deal to buy Wyeth for cash, stock and debt valued then at $68 billion. Pfizer said it expects to close the merger by the end of the year. Pfizer has a strong presence in companion and livestock animal-health products, while Wyeth is strong in animal vaccines, the chief financial officer said, but the companies "have overlap in those areas as well," the Journal reports. He said talks with antitrust authorities are ongoing. D'Amelio also said it's too early to tell if a combined Pfizer-Wyeth would be required to divest itself of any on-the-market or experimental drugs for treating Alzheimer's disease.