Dog Bite Euthanasia in Colorado: Triggers, Thresholds, and Defenses

In Colorado, a court must order a dog euthanized when the owner is convicted — or enters a guilty plea or deferred judgment — in a dangerous-dog case that involved serious bodily injury to a person, the death of a person or domestic animal, or a second or subsequent bite by the same dog under the same owner.¹ Short of those triggers, state law does not force a dog to be put down for biting someone, though many Colorado cities have their own ordinances that can order destruction on a lower showing.

The Three Triggers for Mandatory Euthanasia

Colorado’s dangerous-dog statute, C.R.S. § 18-9-204.5, ties mandatory destruction to the owner’s criminal case rather than to the bite itself. The court has no discretion once one of these conditions is met; the statute uses “shall.” Destruction is ordered when the owner is convicted, pleads guilty, or receives a deferred judgment or deferred prosecution for a dangerous-dog violation that resulted in any of the following:

Serious bodily injury to a person.
Death of a person or a domestic animal.
A second or subsequent conviction involving the same dog and the same owner for biting a person or injuring or killing a domestic animal.¹

A single bite that causes only “bodily injury” — even a bite serious enough to require stitches — does not by itself trigger mandatory euthanasia under state law. It becomes a misdemeanor case against the owner, and the court can impose confinement, muzzling, microchipping, and disclosure requirements on the dog going forward, but the dog can live.¹ A second bite under the same owner changes that.

Where the Line Is: Bodily Injury vs. Serious Bodily Injury

Because the first mandatory trigger turns on severity, the distinction between ordinary bodily injury and serious bodily injury does the heavy lifting in these cases.

The dangerous-dog statute defines “bodily injury” more narrowly than the general criminal code: it means a physical injury producing severe bruising, muscle tears, or skin lacerations that require professional medical treatment, or any injury requiring corrective or cosmetic surgery.¹ A scratch or bruise that heals on its own likely won’t qualify.

“Serious bodily injury” carries the general criminal-code meaning: injury involving a substantial risk of death, serious permanent disfigurement, protracted loss or impairment of any organ or body part, or injuries such as bone fractures, penetrating wounds, or second- or third-degree burns.² A deep puncture that fractures bone, a bite that permanently disfigures a face, or wounds requiring reconstructive surgery all tend to land on the serious-bodily-injury side of the line. That is the line between a case the dog can survive and a case where euthanasia becomes mandatory on the first conviction.

When the Same Dog Has a New Owner

The statute treats repeat-bite cases differently depending on who owns the dog the second time. If the same owner is convicted a second time involving the same dog, destruction is mandatory. If the dog has been transferred and the second conviction is against a different owner, the court may order destruction but is not required to. The judge weighs the new owner’s circumstances. This matters because a convicted owner is required to disclose the dog’s history in writing before transferring it to anyone else, so a new owner typically takes the dog with full knowledge of what the previous owner did or failed to do.¹

How the Process Unfolds After a Serious Bite

From the moment an owner is taken into custody or served with a summons for a dangerous-dog violation, the dog can be seized and placed in a public animal shelter at the owner’s expense while the case is pending. The court can also require the dog to be impounded as a condition of bond. Holding locations include public shelters, licensed boarding facilities, or veterinary clinics chosen by the impound agency.¹ Boarding charges accrue the entire time, which in a drawn-out case can run into real money and often shapes how owners approach a plea.

If the case ends in a conviction, plea, or deferred judgment that meets one of the mandatory triggers, the court orders immediate confiscation (if the dog isn’t already impounded) and placement in a public animal shelter. The destruction itself is carried out “upon exhaustion of any right an owner has to appeal a conviction,” meaning the dog stays alive at the shelter while an appeal is pending.¹ Boarding costs continue to accrue throughout the appeal.

The euthanasia must be performed by a licensed veterinarian using lethal injection.¹

Local Ordinances Can Order Euthanasia on Lower Thresholds

State law is not the only path to destruction. Home Rule cities in Colorado can enact animal-control ordinances that go further than the state statute. A Colorado court has held that regulating dogs by breed on an intra-city basis is a matter of local concern under Home Rule authority, which keeps those ordinances in force even where state law tries to limit breed-specific rules.

Denver’s code is the most prominent example. Chapter 8 of the Denver Municipal Code restricts ownership of pit bull-type breeds (American Pit Bull Terrier, American Staffordshire Terrier, and Staffordshire Bull Terrier) through a breed-restricted permit system administered by Denver Animal Protection, which requires an assessment, microchipping, annual fees, and a two-dog household cap. Owning a restricted breed without a valid permit subjects the dog to impoundment and potential destruction.³

Beyond breed rules, many Colorado municipalities handle aggressive-animal cases through municipal court on standards looser than state criminal law. Some local codes authorize destruction after a single unprovoked attack causing bodily injury, or on a nuisance determination, without requiring a criminal conviction first. The burden of proof at a municipal destruction hearing is typically preponderance of the evidence — more likely than not — rather than the beyond-a-reasonable-doubt standard that governs criminal convictions. Owners at these hearings are entitled to notice of the specific code provisions at issue and the chance to present evidence and witnesses. If you live in a Home Rule city, your local code may be what actually governs whether your dog is put down, not § 18-9-204.5.

Defenses That Can Stop the Case Short of Euthanasia

A dog is not automatically on the hook for every bite. Colorado’s dog-bite statute recognizes several situations where the owner is not liable, and the same facts often undercut a dangerous-dog prosecution before it ever reaches the destruction stage. The main defenses:

The injured person was trespassing on public or private property. Posted “no trespassing” or “beware of dog” signs on the owner’s property strengthen this defense.⁴
The person knowingly provoked the dog.⁴
The person bitten was a veterinary worker, groomer, humane agency staffer, professional handler, trainer, or dog show judge acting in the course of their duties.
The dog was working as a hunting, herding, farm, ranch, or predator-control dog on the owner’s property or under the owner’s control.
The dog was a law enforcement or military dog performing official duties.⁴

These are defenses to civil liability. They do not automatically defeat a dangerous-dog criminal charge, but the same facts — provocation, trespass, a working-dog context — can keep the owner from being convicted in the first place, and without a conviction, mandatory euthanasia under state law never kicks in. A past bite that fell within one of these exceptions can still resurface, though, as evidence of dangerous tendencies if the same dog is involved in a later incident.

1
Justia Law. Colorado Revised Statutes Title 18 Section 18-9-204.5 – Unlawful Ownership of Dangerous Dog
2
Justia Law. Colorado Revised Statutes Title 18 Section 18-1-901 – Definitions
3
City and County of Denver. Breed-Restricted Permits
4
Justia Law. Colorado Revised Statutes Title 13 Section 13-21-124 – Dogs Causing Bodily Injury or Death