GREENFIELD - Greenfield-based Elanco Animal Health Inc. (NYSE: ELAN) is one step closer to adding to its portfolio. Shareholders of Aratana Therapeutics Inc. (Nasdaq: PETX), voted overwhelmingly in favor of proposed $245 million purchase by Elanco.

Ninety-nine percent of Aratana stockholders approved the deal Tuesday. Aratana is a pet therapeutics company based near Kansas City. It specializes in medications for cats and dogs.

The two companies already had a working relationship before the offer to purchase was made in April. In 2016, Elanco agreed to pay $45 million for the licensing rights to Aratana’s Galliprant, an osteoarthritis treatment for dogs.

According to a news release, the closing will take place no later than two business days after all conditions are met.