Pfizer plans to separate its animal health unit into a standalone company, a move Wall Street expected as the largest U.S. drugmaker focuses more intently on its core pharmaceuticals business.

Pfizer said on Thursday that preparations were underway for a public offering of a minority stake in the new animal health company, which would be called Zoetis.

The business, which generated revenue of about $4.2 billion last year, sells an array of medicines, vaccines and other products for livestock and pets. It has more than 9,000 employees and markets products in more than 120 countries.

Pfizer said it would provide details of the proposed IPO in coming months, when it reports second-quarter earnings.

New York-based Pfizer, which agreed in April to sell its baby formula business to Nestle for $11.85 billion, had also been shopping its animal health unit since last year. But company Chief Executive Officer Ian Read has said in recent months that any separation of the animal health business would probably be in the form of an IPO, to avoid hefty taxes.

Pfizer will treat the animal health business as a continuing operation.

The unit competes with thriving animal health operations of Merck & Co, Eli Lilly and Sanofi .

Despite Pfizer's strategy of focusing on its highly profitable prescription drugs, the company has decided to hold onto its array of consumer products, including Centrum vitamins and the Advil painkiller.