Rabies Vaccine Requirements for Dogs in Colorado: What Every Owner Must Know

Rabies is fatal, untreatable once symptoms appear, and transmissible to humans — which is why Colorado takes vaccination seriously. Bats and skunks are the main sources of rabies in Colorado, and dogs that spend time outdoors can encounter either species without warning. Staying current on your dog’s rabies vaccine is not just good practice; in most parts of the state, it is the law.

Colorado’s approach to rabies vaccination is somewhat different from states that carry a single, uniform mandate. The state delegates authority to county and district boards of health, which can require dogs, cats, ferrets, and other mammals in their jurisdiction to be vaccinated against rabies under Colorado Revised Statutes 25-4-607. Understanding how that framework applies to your county — and what happens if your dog’s shots lapse — is what this guide covers.

Important Note: Because rabies vaccination requirements in Colorado are set and enforced at the county level, the rules in your jurisdiction may differ slightly from the general statewide framework described here. Always confirm the specific requirements with your local health department or animal control office.

Is the Rabies Vaccine Required for Dogs in Colorado?

Colorado does not have a single statewide rabies vaccination law for pets. Instead, the state delegates authority to county and district boards of health, which can require dogs, cats, ferrets, and other mammals in their jurisdiction to be vaccinated against rabies under Colorado Revised Statutes 25-4-607. In practice, the vast majority of Colorado counties have exercised this authority.

Most Colorado counties exercise this authority and require vaccination, so the vast majority of pet owners in the state need to keep their animals current on rabies shots. A proposed bill — HB16-1120 — would have created a uniform statewide mandate, but it was introduced in 2016 and never became law, having been postponed indefinitely in the state Senate.

County and district boards of health can order the vaccination of all dogs, cats, and other pet animals within their boundaries, and most do. Those local requirements only take effect after being published in a local newspaper of general circulation. One important guardrail applies statewide regardless of local orders: no county can require vaccination more frequently than what the National Association of State Public Health Veterinarians recommends in its Compendium of Animal Rabies Prevention and Control — meaning counties can require vaccination but cannot, for example, demand annual shots for dogs when the Compendium calls for a three-year booster.

You can also read about how neighboring states handle this issue, including rabies vaccine requirements in New Mexico and requirements in Utah, to see how Colorado’s county-based model compares.

At What Age Must Dogs Be Vaccinated in Colorado?

Counties that require rabies vaccination generally follow the Compendium’s recommended schedule. For dogs and cats, that means a first vaccination by four months of age, a booster one year later, and subsequent boosters every three years when a three-year vaccine product is used. Some local ordinances set a slightly different age threshold — Denver’s Code of Ordinances, for example, states that rabies vaccination is required for dogs over six months of age, and if the dog is older than six months upon acquisition, the dog must be vaccinated within 30 days from acquisition.

In Colorado, the puppy rabies vaccine is generally given at 16 weeks (no earlier than week 15), and the rabies vaccination is good for one year. Most veterinary practices align with this schedule. Most puppies begin vaccines between 6 to 8 weeks old, with a rabies shot administered between 13 to 16 weeks.

If you adopt or purchase a pet that is already older than four months and unvaccinated, expect your county to require vaccination within a set window after you take ownership. A dog, cat, or ferret is considered currently vaccinated 28 days after the primary rabies vaccination, when vaccinated in accordance with the latest version of the Compendium of Animal Rabies Control and Prevention.

Pro Tip: Keep a copy of your dog’s rabies vaccination certificate in a place you can access quickly. You may need it at the vet, a boarding facility, or during an animal control check — and having it on hand avoids delays.

How Often Does Your Dog Need a Rabies Booster in Colorado?

The booster schedule depends on which vaccine product your veterinarian uses. In Colorado, the puppy rabies vaccine is generally given at 16 weeks and is good for one year. For adult dogs, the rabies vaccination is good for three years. For example, a puppy would receive the rabies vaccine at 16 weeks, again at one year, and then again at age four.

Re-vaccination (booster) is required one year following the initial dose, regardless of the animal’s age and regardless of the vaccine administered as the initial dose. After that first booster, the three-year cycle begins. If a three-year labeled rabies vaccine is administered as the initial rabies vaccine dose, a booster dose must still be administered within one year, regardless of the animal’s age at the time the initial dose is administered.

Timing matters more than you might expect. An animal is considered “overdue” — and not currently vaccinated — if just one day beyond the labeled duration of the last rabies vaccine administered, whether that label says one year or three years. After the initial vaccination and the rabies booster shot, dogs need to be vaccinated for rabies regularly, every three years. In line with this, the lifetime Denver dog license still requires renewal to ensure that rabies vaccinations for the animal are up to date.

For a side-by-side look at how booster schedules compare across states, see our coverage of rabies vaccine requirements in Texas and requirements in California.

Who Can Administer a Rabies Vaccine in Colorado?

While the Colorado Revised Statutes gives the local or county board of health the authority to determine the requirements for rabies vaccination, the Colorado Revised Statutes do specify that required rabies vaccinations shall be administered by a licensed veterinarian. This is not a detail you can work around — a vaccination administered by anyone other than a licensed veterinarian (or someone under their indirect supervision) does not count as valid documentation under Colorado law.

A licensed veterinarian must administer the vaccination in accordance with the current version of the Compendium of Animal Rabies Prevention and Control using a vaccine that is licensed by the United States Department of Agriculture for use in those species, and must issue to the owner a rabies vaccination certificate and a tag to be attached to the animal’s collar.

The veterinarian signing a rabies vaccination certificate shall ensure that the person who administered the vaccine is identified on the certificate and has been appropriately trained in vaccine storage, handling, and administration and in the management of adverse events. This means that in some clinic settings, a trained veterinary technician may physically administer the injection, but only under a licensed veterinarian’s indirect supervision — and the supervising veterinarian must sign the certificate.

The Colorado Veterinary Practice Act stipulates that, in general, a veterinarian shall maintain patient records for a minimum of three years after the patient’s last medical examination. This record-keeping requirement supports the chain of documentation that local authorities, boarding facilities, and animal control rely on.

Medical Exemptions From the Rabies Vaccine in Colorado

Colorado law does allow medical exemptions, but the process is formal and owner-initiated exemptions carry no legal weight. A veterinarian, with the written consent of an animal’s owner, may issue a written waiver pursuant to the rules of the health department, exempting an animal from a rabies vaccination order if the veterinarian, in their professional opinion, determines that the rabies inoculation is contraindicated due to the animal’s medical condition. The executive director of the health department shall enact rules allowing for the exemption of an animal from a rabies vaccination due to the medical condition of the animal. The owner of an animal seeking an exemption must provide the veterinarian with written consent for the exemption.

The procedural requirements under Colorado regulations are specific. Pursuant to the rules of the health department, a veterinarian licensed in Colorado may issue a written waiver if vaccination is contraindicated due to the animal’s medical condition. The veterinarian must first have written consent from the animal’s owner. The regulations also require that a veterinary-client-patient relationship be established, that both the veterinarian and the owner sign the official Exemption from Rabies Vaccination Form, and that the veterinarian retain the signed exemption as part of the animal’s medical record and provide a copy to the owner.

The exemption is not permanent. According to Rabies Aware, the exemption is limited to the anticipated duration of the medical condition that precludes the vaccine. A veterinarian supplying a waiver exempting an animal from a rabies vaccination shall not be liable for any subsequent accident, disease, injury, or quarantine that may occur as a result of an animal exempted from a rabies vaccination pursuant to the rules of the health department.

A waiver executed pursuant to this section shall be accepted and recognized by any local or regional authority issuing licenses for the ownership of animals. That means your county’s animal control office cannot reject a properly issued veterinary waiver when you apply for or renew a dog license.

It is also worth noting that exemption is not authorized on the basis of age alone. An elderly dog does not automatically qualify for an exemption — a specific medical contraindication must be documented by a licensed veterinarian.

Proof of Vaccination and Licensing Requirements in Colorado

After vaccination, the veterinarian issues a rabies vaccination certificate and a tag for the animal’s collar. That certificate is the document you will need for licensing, boarding, travel, and any future bite or exposure investigation. Keep it somewhere you can find it quickly, because if your pet bites someone or encounters a wild animal, you will be asked to produce it on short notice.

The vaccination certificate should include the animal’s name, species, breed, age, color or distinctive marks, microchip number (if applicable), vaccination type, vaccine manufacturer, lot number, administration date, and the veterinarian’s details. This level of detail matters during bite investigations or when crossing state lines.

Many Colorado counties and municipalities tie pet licensing directly to rabies vaccination status. Boulder, for instance, requires a current rabies vaccination certificate before issuing or renewing a dog license, and images of rabies tags do not count as documentation.

One thing that will not substitute for a current vaccine: antibody titer testing. A rabies antibody titer is not recognized as proof of immunity in place of vaccination within the United States. Veterinarians do not have legal discretion to substitute a positive titer result for a current vaccine. Some local authorities have accepted titers on a case-by-case basis for animals with documented adverse reactions to vaccines, but this is an exception rather than a right, and no Colorado statute guarantees it.

If you have a cat in the household as well, the same documentation rules apply — see our guide on rabies vaccine requirements for cats in Colorado for the full details.

What Happens If Your Unvaccinated Dog Is Exposed to Rabies in Colorado?

The difference in outcome between a vaccinated and an unvaccinated dog after a rabies exposure is significant. Animals that have documentation of prior rabies vaccination administered by a licensed veterinarian are given a booster rabies vaccine and observed at home for 45 days, watched for disease symptoms.

An unvaccinated dog faces a far more serious situation. Pets that have never had their rabies shots, have no documentation of shots, or had shots administered by someone other than a licensed veterinarian, and have had contact with a known or suspected rabid animal must be either euthanized or placed in a strict facility quarantine for a period of four months (120 days). The quarantine must take place in a facility approved by the local health department and at the expense of the owner. The pet must be completely isolated from humans and other animals during this period to prevent the risk of rabies spreading.

The option of quarantine for unvaccinated pets exposed to rabies may not be available in all circumstances and is assessed on a case-by-case basis. In some situations, euthanasia may be the only option offered.

If your dog’s vaccination is overdue rather than completely absent, the protocol is slightly different. A dog that is overdue for a rabies booster but has documentation of a previous rabies vaccination shall be boostered immediately (within 96 hours of the exposure) and observed at home for a minimum of 45 days. This is to be evaluated on a case-by-case basis with the possibility of additional requirements.

Key Insight: If your dog is exposed to a potentially rabid animal, do not wait. Wash the wound immediately with soap and running water for at least 10 minutes, wear gloves when handling the exposed pet, and contact a veterinarian the same day. The 96-hour window for an emergency booster closes quickly.

Colorado’s exposure protocols apply to other states too — compare how they handle similar situations in our articles on rabies vaccine requirements in Florida and requirements in Ohio.

Penalties for Not Vaccinating Your Dog in Colorado

Sections 25-4-610 and 25-4-611 of the Colorado Revised Statutes, which cover enforcement and impoundment of unvaccinated animals, only apply in counties where a vaccination order is in effect. Because most Colorado counties have such orders in place, most dog owners are subject to these enforcement provisions.

Fine amounts vary by jurisdiction. Denver charges $100 for a first rabies vaccination violation, $250 for a second, and $500 for a third within 12 months. Pueblo County’s fine schedule starts lower at $25 for a first offense but escalates to $300 for five or more violations.

Beyond fines, unvaccinated pets found roaming at large can be impounded. Reclaiming an impounded animal typically involves paying boarding fees, the citation fine, and sometimes a licensing fee on the spot. These costs add up fast and almost always exceed what the vaccination itself would have cost.

If your dog bites someone, the financial exposure grows further. The owner bears all quarantine costs, and if the animal was unvaccinated, the owner may also face civil liability for the bite victim’s medical expenses. If any animal bites a person in Colorado, the bite must be reported to the local health department or health officer under CRS 25-4-603. The biting animal is then quarantined for ten days so it can be observed for signs of rabies.

For budget-conscious owners, the cost of compliance is modest. Low-cost rabies vaccination clinics are available in many Colorado communities, often charging between $10 and $45 per shot. That is a fraction of what a single citation, impoundment fee, or quarantine would cost — and it keeps your dog protected against a disease with a near-100% fatality rate.

For more state-by-state comparisons, see our guides on rabies requirements in Illinois, requirements in Pennsylvania, requirements in Georgia, and requirements in Washington. If you have a ferret alongside your dog, our article on rabies vaccine requirements for ferrets in North Carolina covers a comparable state-level framework.

The bottom line for Colorado dog owners is straightforward: check whether your county has a vaccination order in effect (nearly all do), schedule the first shot by four months of age, follow the one-year and three-year booster schedule, and keep the vaccination certificate where you can find it. Those steps put you in compliance with the law and, more importantly, keep your dog protected against one of the most dangerous diseases it can encounter.