Colo. Rev. Stat. § 35-42-110
Any agent of the bureau or peace officer, as described in section 16-2.5-101, C.R.S., may lawfully euthanize or cause to be euthanized, as defined in section 18-9-201 (2.7), C.R.S., any animal in his or her charge when, in the judgment of such agent or peace officer, and in the opinion of a licensed veterinarian, the animal is experiencing extreme pain or suffering or is severely injured past recovery, severely disabled past recovery, or severely diseased past recovery. In the event a licensed veterinarian is not available, the animal may be euthanized if, by the written certificate of two persons, one of whom may be selected by the owner if the owner so requests, called to view the animal in the presence of the agent, the animal appears to be severely injured past recovery, severely disabled past recovery, severely diseased past recovery, or unfit for any useful purpose.
C.R.S. § 35-42-110
This section is similar to former § 35-42-107 as it existed prior to 1990.