Private equity firms Leonard Green & Partners LP and Texas Pacific Group have agreed to acquire San Diego-based Petco Animal Supplies Inc. for $1.8 billion, including the assumption of debt.

Petco’s stock surged more than 43 percent in Friday trading to around $28. Shares of Petco, which is the second-largest pet-supplies retailer in the U.S. behind Phoenix-based PetsMart Inc., had dropped almost 50 percent in the past year-and-a-half.

Petco investors will receive $29 a share in cash, 49 percent more than Thursday’s closing price of $19.41. If Petco shareholders approve the deal, it should close by year’s end.

Petco operates more than 800 stores in 49 states and also distributes pet and food supplies on the Internet. Los Angeles-based Leonard Green & Partners is the largest private equity firm in Southern California and manages about $3.7 billion of private equity capital. It owned a share of Petco prior to the firm going public in 2002.

The deal is the latest in a string of cash-rich retailers being swooped up by private equity firms. Neiman Marcus Group Inc., Linens ‘n Things Inc. and Shopko Stores Inc. have al been acquired in addition to more recent buyouts of Sports Authority Inc. and Burlington Coat Factory Warehouse Corp.