WESTBROOK — Maine-based Idexx Laboratories Inc. is being added to the Standard and Poor’s 500 stock index.

Idexx CEO Jonathan Ayers said Wednesday it’s an honor to be included on the market index that’s based on 500 large companies traded on the New York Stock Exchange and NASDAQ.

He said it’s a testament to the growth of the Westbrook-based company.

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