Animal diagnostic and health care product company Idexx Laboratories Inc. said Friday its second-quarter net income jumped 31 percent as sales climbed for both its companion animal group and livestock and poultry diagnostics businesses.

The Westbrook, Maine, company also raised its 2011 earnings forecast slightly.

Idexx earned $48.7 million, or 83 cents per share, in the three months that ended June 30. That was up from $37.2 million, or 62 cents per share, in the same quarter last year. Revenue climbed 13 percent to $317.9 million.

Analysts surveyed by FactSet expected, on average, earnings of 72 cents per share on $307.7 million in revenue.

Idexx said sales from its companion animal group rose 12 percent to $259.7 million, helped by its reference laboratory diagnostic and consulting services business and its instrument and consumables product lines. Livestock and poultry sales rose 32 percent to $25.4 million on higher sales of some bovine tests, especially after the company won several government tenders in Germany.

The company also saw some expenses rise. Its cost of revenue climbed 9 percent to $143.8 million, sales and marketing expenses were up 15 percent to $51 million.

Idexx now expects 2011 earnings to range between $2.68 and $2.73 per share, up 2 cents per share from its previous forecast. The company did not change its revenue forecast of $1.21 billion to $1.22 billion.

Analysts expect earnings of $2.69 per share on about $1.2 billion in sales.

Idexx shares climbed nearly 2 percent, or $1.52, to $83 in premarket trading Friday.