The pet owner said he was walking his dog last week in a gated community when the mountain lion jumped out of the bushes, grabbed the dachshund and ate it.
Neighbors told KCNC-TV, Denver, that mountain lion attacks are not unusual in the area.
"We know there are mountain lions in the area, there have been other attacks several years ago," a resident told KCNC. "Our backyard neighbor, a mountain lion climbed a tree and jumped onto her deck and took her dog."
Parks and wildlife officials captured the mountain lion and euthanized it, KCNC reported.