According to the latest update from the USDA Animal and Plant Health Inspection Service on Nov. 21, 35 premises in five states remain under vesicular stomatitis (VS) quarantine. Of those, 27 premises are on their 21-day countdowns for quarantine removal.

Vesicular stomatitis primarily affects cattle, horses, and swine. Infected animals get blisters on their lips, tongues, and coronary bands that enlarge and break, leaving raw tissue that is so painful the animals generally refuse to eat or drink, and they become lame. Severe weight loss usually follows. The disease is thought to be spread by insects.

Officials keep VS-affected farms under quarantine until 21 days after the final lesion is healed on a farm’s last affected animal.

Wyoming has logged the most VS premises this year–137. As of Nov. 21, only 20 of those premises remained under quarantine, 15 of which were on their 21-day countdowns for quarantine removal. Colorado had nine quarantined premises, with six of those on quarantine removal countdowns