WESTBROOK — Idexx Laboratories Inc. said Friday that its net income rose 5 percent in the second quarter on higher sales of diagnostic tests for pets, but its results fell short of Wall Street estimates.

The company lowered its annual guidance, citing unfavorable foreign currency exchange rates.

The veterinary equipment maker said sales of its Catalyst Dx chemistry analyzer and Procyte Dx blood analysis system both improved, and so did sales of disposable products associated with those systems. It also gained revenue as it expanded into new markets. That helped revenue from its companion animal business. Revenue from its water testing business inched higher and revenue from its livestock and poultry division decreased.

Shares fell $2.56, or 2.8 percent, to $90.15 in midday trading. They are still near the higher end of their 52-week range of $63.83 to $98.38.

The company said its net income increased to $51.3 million, or 91 cents per share, in the rthree months ended June 30, from $48.7 million, or 83 cents per share, a year ago. Revenue grew 6 percent to $335.6 million from $317.9 million.

Analysts were projecting net income of 90 cents per share on $338.9 million in revenue, according to FactSet.

Idexx said revenue from its companion animal business rose 7 percent to $278.3 million. Revenue from the water business edged up to $22 million from $21.5 million on better sales of Colilert test, which detect E. coli and coliform bacteria. Livestock and poultry diagnostics revenue slipped to $23.1 million from $25.4 million after European Union regulatory changed their requirements for testing for mad cow disease.

Idexx lowered its earnings and revenue forecasts. It expects to report a full-year profit of $3.05 to $3.10 per share on $1.3 billion to $1.31 billion in revenue. The new estimates are about equal to Idexx’s original guidance from January. It raised its estimates in April, saying foreign currency exchange rates were helping its results.

Analysts expect the company to report a profit of $3.10 per share and $1.31 billion in revenue on average.