Mastiff Adoption in Frederick, CO: Mastiff Puppies for Sale in Frederick, CO

Adopt a Mastiff near you in Frederick, 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 Frederick, Colorado

These Mastiffs are available for adoption close to Frederick, Colorado.

Barnaby

Mastiff

Male, 3 yrs

Mead, CO

Size

(when grown) X-Large 101 lbs (46 kg) or more

Details

Good with kids, Good with dogs, House-trained, Spayed or Neutered, Shots are up-to-date,

Story

Meet your new oversized shadow with a heart of gold 💛 This 4-5 year-old English Mastiff is basically a real-life version of The Beast—big, lovable, and way less intimidating once you get to know him. At a petite 180 lbs, he firmly believes he’s a lap dog. He does great with both kids and adults. He loves to lean into his pets (all 180 pounds of him), and if you dare to stop, he’ll gently place a paw on you as a polite reminder to keep going. He’s a social guy who gets along well with dogs of all sizes, from tiny sidekicks to fellow giants. And while he may look like he could run a marathon, he actually tires out pretty quickly so expect short bursts of play followed by legendary naps. He’s an enthusiastic passenger for any and all car rides, too! A few bonus features: Drools like a champion (seriously, keep a towel handy) Gives world-class cuddles Doubles as a weighted blanket If you’re looking for a gentle giant who will adore your family, charm your friends, and leave a little drool trail of love wherever he goes, this is your guy. Barnaby is being fostered in Broomfield, Colorado. *We require all adopters to come to Colorado to adopt. *We do not transport dogs.* You can view this wonderful dog at https://www.milehighcanine.org/post/dogs/barnaby/. You can apply for our wonderful dogs at https://www.milehighcanine.org/adopt/adoption-application/.

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Special Needs

Sabrina

Mastiff American Bulldog

Female, 7 yrs 7 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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NALA

Mastiff

Female, 6 mos

Denver, CO

Size

(when grown) X-Large 101 lbs (46 kg) or more

Details

Spayed or Neutered,

Story

Came in with A430806Initially shy and can be vocal. Loves people and good at meeting other dogs.

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Ombre

Mastiff Boxer

Male, 4 yrs 4 mos

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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Tenille

Mastiff

Female, 4 yrs 9 mos

Aurora, CO

Size

(when grown) X-Large 101 lbs (46 kg) or more

Details

Story

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Zeus

Mastiff

Male, Adult

Fort Collins, CO

Size

(when grown) X-Large 101 lbs (46 kg) or more

Details

Good with kids, House-trained, Spayed or Neutered,

Story

Hi, I’m Zeus, a 6-year-old Mastiff–Rottweiler mix weighing in at a totally manageable 103 lbs (even though I firmly believe I’m lap-sized). If you’re looking for world-class cuddles, look no further. I was surrendered to my foster by my family because my parents were getting divorced. Neither could find space for me in their new homes. It's been a hard transition but I'm finally coming out of my shell. I’m sweet, soft-hearted, and full of love, living up to the title of gentle giant. I adore dogs, do great with kids, and I’m totally cool with cats—no chasing, just peaceful coexistence. I’m fully potty trained, walk beautifully on a leash (no pulling here!), and I know my basics commands like sit and drop it. I am a good boy and proud of it. Even though I am 6 at heart, I’m still a big puppy. My determination to catch my own tail and joyful energy is guaranteed to make you laugh even on your worst day. Toys? Oh, I love them… but fair warning: if it squeaks, I will surgically remove the squeaker with my teeth. A few things I’m working on: I can be shy and bark when people show up unannounced, men especially, but I’m working hard on my confidence. Public outings are helping a lot, and I’m improving every day. I don’t love being alone and would do best with someone who has time for me—or even better, another medium to large dog to keep me company. I’m a bit of a counter surfer and an occasional trash inspector. A locked trash can solves that problem completely. But my foster has yet to find a place high enough on her shelves to keep me from having a second breakfast. I'm clever but not destructive. If you’re looking for a loyal shadow, a cuddle buddy, and a companion who will love you endlessly, I might just be your guy.March 10, 2026, 3:01 pm

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Mastiff puppies and dogs in Frederick, Colorado

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Mastiff puppies and dogs in Frederick, Colorado

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Adopt a Mastiff near you in Frederick, 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 Frederick, Colorado

These Mastiffs are available for adoption close to Frederick, Colorado.

Search for a Mastiff puppy or dog

Mastiff puppies and dogs in nearby cities

Related breeds in Frederick, Colorado

Mastiff shelters & rescues in Frederick, Colorado

Looking for a specific shelter or rescue?

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

Mastiff basics

Mastiff basics