Idexx Laboratories Inc. experienced double-digit revenue and profit growth in the second quarter, with net income beating analysts’ expectations by 4 cents per share, the company reported Friday.

However, news that the company is shifting its business model to cut out third-party product distributors sent its stock price plummeting more than $4 a share despite the healthy earnings.

The Westbrook maker of diagnostic testing equipment for animals, dairy products and water quality said in its quarterly earnings report that revenue for the quarter was $390.1 million, up 11 percent from $352.6 million in the second quarter of 2013.

The company’s net income for the quarter was $57.2 million, or $1.10 per share, up 11 percent from $54 million, or 99 cents per share, during the same quarter a year earlier.

Revenue growth from the company’s international sales outpaced domestic sales growth at 11.9 percent versus 9.7 percent.

“In the second quarter, we continued to accelerate our growth momentum,” company Chairman and CEO Jonathan Ayers said in a news release. “We are seeing clear benefits from our investments in innovation and enhanced commercial capability globally, including our transformation of the North American diagnostic sales and marketing organization in 2013.”

Idexx announced plans to begin selling all of its products directly to customers, rather than selling some of them through a third party as it has done in the past. Ayers called the move “a natural evolution of our business model” and said it will allow the company to expand significantly its direct sales coverage and capacity.

Kevin Ellich, a senior research analyst with Piper Jaffray, said the move to increase direct sales could hurt the company’s bottom line in the near term, but that it likely would have long-term benefits.

“The shift to an all-direct distribution model is an interesting change, but could cause some near-term disruption and distributors are no longer incentivized to push (Idexx) rapid assay or consumable products,” Ellich said in his analyst report. “We think this could have a slightly negative impact on sales for the remainder of 2014. Longer-term, this change is expected to add incremental revenue of $50 (million) to $55 million of annual recurring diagnostic revenues.”

Idexx stock trades on the Nasdaq exchange under the symbol IDXX.

The company’s share price fell $4.18, or 3.14 percent, in trading Friday to end the day at $128.87, despite the positive earnings report. Trading volume was four times the company’s three-month average as investors sold off their stock in droves.

Morningstar senior equity analyst Debbie Wang said investors were responding not to Idexx’s “stellar” earnings but to the news about cutting third-party distributors out of the sales process.

Wang described the move as “unorthodox” for the industry and said it may have spooked some investors.

“There’s uncertainty,” she said about the shift to a new business model. “Investors hate that.”

Still, Wang agreed with Ellich that, eventually, the change should be good for Idexx as long as it is properly executed.

“Over the longer haul, it’s a pretty smart move, in my mind,” she said.