Animal Control

The maximum number of animals per residential dwelling is a total of four (4).  Domesticated potbellied pigs are allowed but must weigh less than seventy (70) pounds. If you have dogs, cats, and a pig, the maximum is four (4) total in any combination. The only exception is a litter of dogs or cats from owned animals under three (3) months of age.

Also allowed are the following: Two (2) ducks, three (3) adult rabbits, five (5) adult hamsters, gerbils or guinea pigs. Birds, aquatic animals, insects, snakes and reptiles that are not a health hazard are allowed. Poisonous or otherwise dangerous animals and snakes over six feet are not allowed.

Chickens are allowed under specific circumstances. For additional information, refer to the Thornton City Code.

Chickens are allowed in Thornton if the following requirements are met:

1. Backyard chickens can be kept at single-family detached homes, which is a home that is not attached to another. Chickens are not allowed on lots developed with attached dwellings, such as townhomes, apartments/condominiums, or paired homes (duplexes), or in manufactured home parks.
2. Six chickens are allowed per single-family detached dwelling.
3. Only chicken hens (female chickens) are allowed. Roosters (male chickens) are prohibited.
4. Chickens must be kept in the backyard only, and a chicken coop must be provided. The yard must be fenced so that the chickens cannot leave the property.
5. Chicken coops cannot exceed 120 square feet or seven feet in height, and must be placed at least five feet from the side and rear property lines. Only one coop is allowed.
6. Coops must be fully enclosed to protect the chickens from predators and provide adequate shelter from inclement weather.
7. A minimum of six square feet of space per chicken must be provided in the coop.
8. During the day, chickens may roam the backyard or be kept in a chicken run. From dawn until dusk, the chickens must be kept inside the coop.
9. Water must be provided at all times.
10. Regular cleaning and removal of excrement is required.
11. Chicken feed and waste must be stored in a manner to discourage attracting pests and predators.
12. On-site butchering or slaughtering is prohibited.
13. A permit is not required.

According to city ordinance, it shall be unlawful for any person or owner to keep or maintain any animal that disturbs or tends to disturb the repose of the community by unreasonable, excessive, continuous, untimely, or habitual barking, yelping, meowing, squawking, squealing, or other noise.  Any animal owner who fails to comply with this ordinance and is found guilty can be fined a sum not less than $100. Animal Control Officers will not investigate anonymous complaints and must speak to a reporting person.

To report a violation of this ordinance call the Thornton Police non-emergency number, 720-977-5150, or if an emergency exists call 9-1-1. 

If you would like to report an animal control violation, you will need to call dispatch at 720-977-5150.

Animal Control Officers are on duty 7 days a week from 8 a.m. to 6 p.m. Animal Control Officers enforce animal ordinances such as dog at large, barking dogs, animal abuse and many other animal ordinances. Partnering with Animal Control is a way to help people and animals live together in harmony. You can help by practicing responsible pet ownership:

• Have your pet spayed or neutered
• Don't let your pet run free
• Keep your pets on a leash
• Have your pet vaccinated yearly.

With Animal Control and your help, people and animals can live together in harmony.  

If an animal has bitten a person, it must be reported to law enforcement. If the skin on the person is broken, a bite report is required. The animal will either be closely confined by its owner or impounded by animal control, at the election of an animal control officer.

To report an animal bite, call Thornton Communications Center non-emergency number, 720-977-5150, or if an emergency exists call 9-1-1. 

The quarantine period shall not be less than ten (10) days, depending on the type of animal and the situation. For dogs and cats in good health, the quarantine period will be ten (10) days. If the animal is inoculated for rabies during the ten (10) day quarantine, an additional ten (10) days will be required. If the animal is impounded for quarantine, the owner is responsible for all fees. The owner can be issued a summons if the bite was a result of an unprovoked attack either on or off its property.  

Aggressive Animals City Code 

Animal Attacks City Code

If you wish to report a deceased stray animal within the Thornton City limits please call the Thornton Communications Center non-emergency number, 720-977-5150. If the deceased animal presents a dangerous hazard please call 9-1-1.

It is the responsibility of a pet owner to properly dispose of any deceased pet. Deceased pets may be disposed of by taking the animal to the Adams County Animal Shelter and paying a disposal fee, or the pet may be taken to any animal hospital. If you need advice or assistance with the disposal of your animal please request to dispatch that an animal control officer contact you.

Rabies is caused by a virus that can be carried in all warm-blooded animals. Wild animals such as raccoons, bats, skunks and foxes are most commonly the carriers, and can transmit the virus through their saliva. These animals may infect a person or household pet if there is contact that involves a bite and breakage of skin.

All animal bites, regardless of whether from a household pet or wild animal, should be reported to Thornton Animal Control or Police Department by calling 9-1-1.

Animal Control is charged with recording all incidents of animal bites in the city. Furthermore, they can assist you in locating the animal that caused the bite. It is important to know which animal caused the bite because it may need to be quarantined for a prescribed length of time for observation, regardless of vaccination history.  Adults should caution children to use care when being approached by strange animals.

Adams County Health Department can also provide advice on animal bites and rabies, and can be contacted at 303-220-9200.

All dogs and cats over the age of six (6) months are required by City code to be vaccinated against rabies. 

If you have lost an animal in the city, you can report it to Thornton Communications Center at 720-977-5150.  Please provide a description of the animal and any information on the animal’s tags.  You should also call the Riverdale Animal Shelter at 720-523-7387 to check and see if the animal is there.

To report a found animal, contact the Thornton Communications Center by calling 720-977-5150. 

The City of Thornton shelters its animals at the Riverdale Animal Shelter, located at 12155 Park Bvld. in Brighton, phone number 720-523-7387. The shelter’s hours of operation are 11 a.m. to 6 p.m. Monday through Friday, and 10 a.m. to 5 p.m. Saturday and Sunday. The shelter is closed on holidays.

The animals that are impounded by the City of Thornton are held for five days, excluding holidays. The Riverdale Animal Shelter also has animals available for adoption.

Uncontrolled animals cause traffic accidents, destroy property, and can bite people.  A domestic animal is considered at large if it is off the property of its owner without being under direct physical restraint (leash, cord, or chain).

If you see an animal running loose or have found a lost animal, call 720-977-5150.  Animal Control Officers generally will not impound cats unless they are confined or in a cat trap. Any person who violates any of the provisions shall, upon conviction, be fined not less than 100 dollars.

City Code Animal at Large

Wild animals often will choose to live in residential areas. These animals can be entertaining to watch, but may also cause property destruction and become a nuisance. If you are experiencing an issue with wildlife, consult the Colorado Parks and Wildlife main website or contact a local wildlife re-locator. Learn more about animals around town.

Thornton Animal Control does not handle nuisance wildlife. They will, however, respond if a wild animal is sick or injured.

To adopt an animal, please contact the Riverdale Animal Shelter located at 12155 Park Blvd. in Brighton. Animals are available for adoption on a daily basis. The shelter hours are 11 a.m. to 6 p.m. Monday through Friday, and 10 a.m. to 5 p.m. Saturday and Sunday. The shelter is closed on holidays.

The adoption fee varies depending on the type of animal you are looking to adopt, so please consult their webpage or contact them by phone at 720-523-7387. The adoption fee includes neutering/spaying, all vaccines, microchipping and deworming.  This applies to both purebreds and mixed breeds. All dogs and cats will be spayed or neutered prior to being released for adoption. The adoption fee for rabbits, hamsters, guinea pigs, etc., ranges from $8 to $100.

For additional information, please call the Riverdale Animal Shelter at 720-523-7387 or email adcoshelter@adcogov.org 

Facilities such as kennels, veterinary hospitals, and pet shops are required to obtain a commercial animal license to operate in the City.

To obtain the application and fee information, please call the City Clerk’s office at 303-538-7230 or download the Commercial Animal License Application.  

If you find a sick or injured stray animal of any type, call Thornton's Communications Center at 720-977-5150.

If your pet becomes ill or is injured, it is the pet owner’s responsibility to provide appropriate care through a veterinarian. 

Thornton does not require dogs, cats and pot-bellied pigs to be licensed with the City. Although pets are not required to wear a City animal license, animals older than six months of age must still get a rabies vaccination and wear the rabies tag that is given out by their veterinarian. Pet owners are encouraged to put I.D. tags with the name of the animal and a phone number on their pet's collar.