Westbrook-based Idexx Laboratories Inc. is being added to the Nasdaq-100 Index, months after being added to the Standard and Poor’s 500.

Idexx has more than 7,000 workers and is a major producer of pet diagnostic tests and other products for veterinarians. Its products are sold in 175 countries.

CEO Jonathan Ayers said Monday that he’s pleased Idexx is on the Nasdaq list alongside growth-oriented companies that are “innovators of the modern economy.”

Idexx was added to the S&P 500 stock index in January. The announcement that it’s joining the Nasdaq-100 index and two other Nasdaq indexes was made before the market opened Monday.