* Animal health unit to sell 86.1 mln shares at $22-$25 per share
* IPO to raise up to $2.2 bln
* Pfizer to hold 413.9 mln Class B Zoetis shares post IPO
* IPO to be priced on Jan. 31; Shares to begin trading on Feb. 1
Jan 17 (Reuters) - Pfizer Inc's unit Zoetis Inc plans to sell 86.1 million shares at between $22 and $25 each in an initial public offering that could value the animal health business at as much as $12.5 billion.
At the top-end of the expected range, the offering would raise about $2.2 billion.
The Wall Street Journal reported last month that the Zoetis IPO was likely by January or February, and that it could raise about $4 billion.
Pfizer said in June last year that it planned to separate its animal-health unit, which sells medicines, vaccines and other products for livestock and pets, into a standalone company.
The unit reported revenue of $3.16 billion, or about 7 percent of Pfizer's overall revenue, for the nine months ended Sept. 30, 2012.
Zoetis had filed with regulators in August a placeholder amount of up to $100 million, as the largest U.S. drugmaker looked to spin off the unit and narrow its focus on its core prescription drug business.
Zoetis will use a dual-class share structure, with Pfizer offering all the Class A common shares in the IPO.
Pfizer will hold 413.9 million Class B Zoetis shares following the offering, each of which would be convertible to one Class A share at any time, according to an amended regulatory filing. ()
Both classes of shares will have identical rights and voting power on all matters submitted to stockholder vote, other than the election of directors.
The Zoetis IPO is scheduled to price on Jan. 31 and shares are expected to begin trading under the symbol "ZTS" on the New York Stock Exchange on Feb. 1.
JP Morgan, BofA Merrill Lynch and Morgan Stanley are the lead underwriters to the offering.