A cattle farm west of Surrey, England being investigated for a foot-and-mouth outbreak in August of 2007. A bigger epidemic struck Britain's agriculture industry in 2001.

LOS ANGELES — America's swine and cattle populations are vulnerable to the deadly and highly contagious foot-and-mouth disease, and "efforts to prepare for a potential outbreak could be strengthened," according to a U.S. government watchdog's new report.

The Government Accountability Office report said the U.S. Department of Agriculture "may not have a sufficient supply of FMD vaccine to control more than a small outbreak because of limited resources to obtain vaccine." It also said an epidemic could prove costly to the nation's livestock industry and the federal government.

Foot-and-mouth disease, or FMD, in livestock is found roughly in about two-thirds of the world, but the U.S. hasn't experienced an outbreak since the 1920s.

"The United States is vulnerable to FMD transmission, given the large size and mobility of the U.S. livestock sector," the GAO said in the report published last week. "An FMD outbreak in the United States could have serious economic impacts, in part because trade partners would likely halt all imports of U.S. livestock and livestock products until the disease was eradicated."

The agency said exports of U.S. swine, cattle and dairy products totaled more than $19 billion in 2017. It warned that those shipments after an outbreak "would likely stop or be sharply reduced. Moreover, in a widespread outbreak, the scale of federal compensation payments could be substantial."

The disease affects domestic and wild cloven-hoofed animals including cattle, swine and goats. FMD is not considered dangerous to humans but is frequently fatal to younger animals.

The 2018 Farm Bill signed into law in December by President Donald Trump included more funding for USDA's animal health and disease preparedness programs, such as money for an expanded animal vaccine bank for FMD. Sen. Amy Klobuchar of Minnesota, a 2020 Democratic presidential contender, last year introduced the provision more animal disease funding and cited it in an op-ed piece last week talking about the Farm Bill.