The sources told the paper a final decision on the offering would depend on market conditions.

The largest U.S. drug-maker believed that an IPO is the way to go for Zoetis, as the unit's hoped-for $20 billion valuation has priced it out of the range of potential strategic buyers, the Journal said.

Pfizer said in June that it planned to separate its animal-health unit, which sells medicines, vaccines and other products for livestock and pets, into a standalone company.

Zoetis makes Palladia, the first drug to be approved by the FDA for treating cancer in dogs, and has developed the first swine vaccine for pandemic H1N1 Influenza Virus in the United States.

Zoetis Inc had filed for a $100 million initial public offering in August. The amount of money a company says it plans to raise in its first IPO filings is used to calculate registration fees and the final size of the IPO could be different.

Industry analysts have valued the Pfizer animal-health business at $15 billion or more based upon its revenue of $4.2 billion in 2011.

A Pfizer spokeswoman declined to comment, citing the "quiet period" before the transaction.

(Reporting By Vishal Krishnan Menon and Tej Sapru in Bangalore; Editing by Muralikumar Anantharaman)

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