DERBY, Vt. — This summer, Steve Sanford had to tell 106 dairy farmers in rural northern Vermont he could no longer treat their cows.

Battling degenerative arthritis, the 56-year-old large animal veterinarian can't do the physically challenging work any more. Worse, he can't find anyone who will, having already tried to recruit a bovine veterinarian to join his practice.

"Believe me, I've looked under every stone, there is no one out there," he said.

The shortage of large animal veterinarians isn't limited to Vermont. In New England, there will be 1,036 vet vacancies in the next six years, according to a June study by the Cummings School of Veterinary Medicine, at Tufts University. In the same time period, over a quarter of the more than 100 specialized food animal veterinarians will reach retirement age, the study found.

Fewer people are interested in large animal veterinary medicine, said David Kirkpatrick, a spokesman for the American Veterinary Medical Association. With a decline in the number of family farms, fewer children are getting exposed to agriculture, he said.

The first years on the job, too, can be daunting. Saddled with an average of $106,000 in school debt and an average starting salary of $53,000, large animal vets don't make what small animal doctors do — about $60,000 a year to start.

Last year, 60 percent of vet school graduates went into private practice, with just 5 percent in large animal veterinary medicine exclusively and 41 percent in small animal practice, according to Kirkpatrick.