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Mastiff puppies and dogs in Longmont, Colorado

Looking for a Mastiff puppy or dog in Longmont, Colorado? Adopt a Pet can help you find an adorable Mastiff near you.

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Adopt a Mastiff near you Mastiff in cities near Longmont, Colorado Other pups in Longmont, Colorado Search for a Mastiff puppy or dog near you Browse Mastiff puppies and dogs in nearby cities Browse related breeds in Longmont, Colorado Mastiff shelters and rescues in Longmont, Colorado Learn more about adopting a Mastiff puppy or dog

Adopt a Mastiff near you in Longmont, Colorado

We don't see any Mastiffs available for adoption right now, but new adoptable pets are added every day. Try a different search below!

Or, how about these Mastiffs in cities near Longmont, Colorado

These Mastiffs are available for adoption close to Longmont, Colorado.
We'll also keep you updated on Ombre's adoption status with email updates.
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Ombre

Mastiff Boxer

Male, 4 yrs
Fort Collins, CO
Size
(when grown) Large 61-100 lbs (28-45 kg)
Details
Spayed or Neutered,
Story
This pups adoption fee has been partially sponsored by All Aboard or an All Aboard partner! The new adoption fee is reflected on the profile. IMPORTANT NOTE REGARDING THIS DOG: Ombre can be easily startled by new people and things. He is occasionally slower to meeting new people, especially men, and other dogs. Ombre has the potential to get overwhelmed easily and can resource guard. Ombre needs an adopter who is patient and willing to continue his training. Ombre is big guy with a lot of love to give! He came to us with a few quirks that his foster has been helping him work through and he is constantly making progress! He does need an experienced adopter who will be dedicated to continued positive reinforcement training and ongoing socialization. He has come a long way since his arrival in January 2023 and needs the perfect partner in crime to help him continue making progress! Ombre can be a bit skittish with new sounds or unexpected movements and can resource guard at times. He is occasionally slow to warm up to new men and other dogs, but not consistently! He can get overwhelmed in new high-activity environments, so continued socialization is a must. Ombre is very loving and curious, and acts like he is his foster's shadow. This loving boy is a classic case of a dog who is worth the effort! With the right, experienced adopter who is committed to setting him up for success through continued training and socialization, Ombre will absolutely blossom into his adopter's most dedicated friend! He is house and kennel trained. Playgroup - https://youtube.com/shorts/Brmr_wwiRKs ADOPTION FEE: $75 We are a foster-based rescue and do not generally have pups available to meet at our office except during adoption events on Saturdays. Interested in this pup? The first step is to complete our online application by clicking the "Apply for Adoption" button. Please note that we are only able to finalize adoptions at events for approved adopters. The earlier you apply, the better as it takes time to review and approve applications. We host adoption events almost every Saturday from 11:00am to 2:00pm at Petco in Fort Collins (2211 S College Ave. STE 200, Fort Collins, CO 80525)! Check our Instagram and/or Facebook page for info on where we will be hosting adoptions this weekend! All Aboard Animal Rescue saves dogs and puppies from high-kill shelters in other states. These pups are brought to Colorado, where they are required to be spayed or neutered - breaking the cycle of unwanted litters of puppies who end up as strays! Please consider supporting us in this mission by adopting, fostering, volunteering, or donating.

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We'll also keep you updated on Sabrina's adoption status with email updates.
Special Needs
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Sabrina

Mastiff American Bulldog

Female, 7 yrs 3 mos
Boulder, CO
Size
(when grown) X-Large 101 lbs (46 kg) or more
Details
Needs special attention, Needs experienced adopter, House-trained, Spayed or Neutered, Shots are up-to-date,
Story
Meet Sabrina, a gentle 6-year-old Mastiff mix who’s in need of a special forever home. Sabrina is living with mast cell tumors (MCT) due to cancer and is currently on medication to keep her as comfortable as possible. She requires a loving home that is prepared to offer her hospice care and a peaceful environment. Sabrina can be shy with new people and may give a warning growl or snap if approached when she’s not ready. However, once she builds trust, she becomes deeply affectionate and very attached to her people. She gets along well with mellow dogs and will thrive in a calm household where she can feel safe and loved. If you have a compassionate heart and are ready to provide a supportive and caring home for a special dog like Sabrina, you’ll find a loyal and loving companion in her.

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We'll also keep you updated on Charlie Brown's adoption status with email updates.
Photo of Charlie Brown

Charlie Brown

Mastiff Pit Bull Terrier

Male
Fort Collins, CO
Size
(when grown) -
Details
Spayed or Neutered,
Story
Charlie Brown is a going to be a very big boy! He is the laziest of all his brothers and sisters. He gets along well with cats, dogs and kiddos. Click on the link to get your application in today!    Adoption/Foster application . December 27, 2025, 5:42 pm

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We'll also keep you updated on Shroeder's adoption status with email updates.
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Shroeder

Mastiff

Male
Fort Collins, CO
Size
(when grown) -
Details
Good with kids, Good with dogs, Good with cats, Spayed or Neutered,
Story
Meet Shroeder! This big puppy is going to be a big, sweet, lazy lunk. He's good with cats, dogs and kiddos. Email us at info@untilhome.org for more info or click here to fill out our application. Adoption/Foster application . December 27, 2025, 2:43 pm

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We'll also keep you updated on HOOCH's adoption status with email updates.
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HOOCH

Mastiff

Male, Senior
Denver, CO
Size
(when grown) Large 61-100 lbs (28-45 kg)
Details
Spayed or Neutered,
Story
December 31, 2025, 3:36 pm

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We'll also keep you updated on Luna's adoption status with email updates.
Photo of Luna

Luna

Mastiff Rottweiler

Female, Adult
Golden, CO
Size
(when grown) X-Large 101 lbs (46 kg) or more
Details
Spayed or Neutered,
Story
Luna is a big dog who loves the snow! She will enjoy a gentle transition where she can take life one step at a time and not be expected to be a social butterfly right off the bat. Luna will only be rehomed to a family without children or with children 10 or older, and she is recommended for a home without other dogs at this time. Primary Color: Fawn Weight: 92.6 Age: 5yrs 1mths 0wks

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Search for a Mastiff puppy or dog

Use the search tool below to browse adoptable Mastiff puppies and adults Mastiff in Longmont, Colorado.

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Mastiff puppies and dogs in nearby cities

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Related breeds in Longmont, Colorado

Bullmastiffs in Longmont, Colorado Neapolitan Mastiffs in Longmont, Colorado Saint Bernards in Longmont, Colorado

Mastiff shelters & rescues in Longmont, Colorado

There are animal shelters and rescues that focus specifically on finding great homes for Mastiff puppies in Longmont, Colorado. Browse these Mastiff rescues and shelters below.

Here are a few organizations closest to you:

Rescue

27.7 miles

All Aboard Animal Rescue

Fort Collins, CO 80526

Pet Types: cats, dogs

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Rescue

29.6 miles

Ace of Hearts Dog Rescue - CO Transport Stop

711 Walnut St, Boulder, CO 80203

Pet Types: dogs

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Rescue

33.1 miles

Until They're Home

Fort Collins, CO 80524

Pet Types: cats, dogs, rabbits, small animals

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Shelter

33.7 miles

Humane Colorado

2080 S Quebec St, Denver, CO 80231

Pet Types: cats, dogs, horses, rabbits, small animals

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Shelter

33.9 miles

Foothills Animal Shelter

580 McIntyre St., Golden, CO 80401

Pet Types: cats, birds, dogs, rabbits, reptiles, small animals

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Rescue

37.8 miles

Big Dogs Huge Paws, Inc

PO Box 460699, Aurora, CO 80046

Pet Types: dogs

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Rescue

40.2 miles

L.O.L.A.'S Rescue

6005 S. Taft Way, Littleton, CO 80127

Pet Types: dogs

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Shelter

48.7 miles

Grand County Animal Shelter

3475 CR 57, Granby, CO 80446

Pet Types: cats, birds, dogs, rabbits, reptiles, small animals

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Looking for a specific shelter or rescue?

If you're not seeing what you're looking for, try our shelter and rescue search. We have more than 17,000 organizations in our database with furry pals waiting for a new home!

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Want to learn more about adopting a Mastiff puppy or dog?

We've got all the info you need on adopting and caring for a Mastiff puppy. Check out the links below for everything you ever wanted to know about Mastiff puppies and adults.

Mastiff basics

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Where do Mastiffs come from? How many types of Mastiffs are there? From the history of the breed to question about average height, weight and size, brush up on these basic facts about the Mastiff.

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