Brian Allen, the owner of Green Goat Landscapers, said in a Facebook post the herd was stolen from a field in Morgan Hill on the weekend after Thanksgiving.
Allen said he left the goats and their guardian dog behind an electric fence so that they could feed on an abandoned driving range. The thieves shut off the power to the electric fence, cut a hole through it and herded the goats into his trailer before driving off, he said.
The trailer was later found, but the goats are still missing.
The animals, which altogether are worth more than $10,000, are expected to give birth in about two months, Allen told Bay Area television station KPIX. They're used for eco-friendly fire prevention and weed abatement.
"This is really kind of a big set back for us. It's going to make it hard this year," Allen said.
Allen is offering a reward for anybody with information about the goats' whereabouts.
The Associated Press contributed to this report.