A growing number of small-business owners are only reluctantly planning vacations this summer, with many fretting about customers while they're away.

Entrepreneurs have strong emotional attachments to their businesses, so they always worry about taking time off.

"Our businesses are our lives," says Rebecca Staton-Reinstein, a business consultant and trainer in North Miami Beach, Fla.

Yet this summer, the combination of stiffer competition, soaring oil prices, hard-to-find workers and inflation jitters are making the coming months an especially dicey time to be away.

Owners say they worry most about jeopardizing a major client account by being away from the office: 46 percent cited that as their top concern, American Express found in an April survey of 618 owners and managers. That's up from 26 percent three years ago, when the financial services giant started surveying small-business vacation plans.

Many owners trim time off rather than delegate work, says Peter Horan, chief executive at AllBusiness.com, a Web site offering management advice to companies. That chains owners to their desks, pinching growth.

"You can only sleep in the office and eat cold pizza for so long," Horan says.

Pat Lyon, 52, is one of the nervous vacationers. He started a document-imaging company, US Imaging of Northwest Pennsylvania, about 18 months ago. It makes electronic copies of business records for small companies, such as funeral homes, wanting to reduce storage costs for paper documents.

Lyon has two part-time employees, not enough to make him comfortable being away for long from his fledgling enterprise.

"You just don't want anything to go wrong," he said.

Lyon, his wife and four kids will only take day trips this summer to see the sights in Pittsburgh and other cities in the region.

He worries that higher gas prices, up an average 36 percent nationwide from a year ago, could sap economic growth — and his company's revenue — if customers scale back.

The struggle to make a clean break from work is among entrepreneurs' biggest complaints, says the Strategic Coach in Toronto, a consultant to entrepreneurs earning at least $100,000 a year.

The firm recommends that owners take off a generous 150 days annually, including weekends, to recharge their batteries, says Catherine Nomura, director of business development.

"You're just not as creative, or able to respond as well, if you don't take a vacation," she says.

Hiring qualified workers who can run the business in the owner's absence is a big part of entrepreneurial worries this summer, says Susan Sobbett, president of American Express' small-business division.

"It's a very tight job market, and it makes it really tough to find the right staff to grow and run the business," she says.