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

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.

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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Effie

Mastiff

Female, Young

Denver, CO

Size

(when grown) Large 61-100 lbs (28-45 kg)

Details

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

Story

Meet Effie, 1 year and 2 month old Mastiff mix who has a healthy appreciation for both naps and play time! She is a bit timid at first, but warms up very quickly. Effie is still young, so she is fairly quick to train and to learn new things. Effie is an amazing, kind dog - She is good with cats, dogs, and kids. After adopting Effie from the Humane Society, we discovered our senior cat was having an allergic reaction to her that worsened his pre-existing medical condition. For the sake of our cat’s health, we have made the difficult decision to find a new home for Effie. Effie thrives in a home with someone who can snuggle, play, and spend quality time with her.

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Special Needs

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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RUBY

Mastiff

Female, 1 yr 11 mos

Denver, CO

Size

(when grown) Large 61-100 lbs (28-45 kg)

Details

Spayed or Neutered,

Story

Meet Ruby, a sweet and goofy adult dog with a shy yet energetic spirit. She thrives in the company of older, calmer dogs and is best suited for a home with older children who understand her need for a gentle approach. Ruby`s shyness belies her playful nature, and once comfortable, her charming and spirited side shines brightly. She would make a delightful companion for anyone willing to give her the patience and love she deserves. Adopt Ruby and discover the joy of watching her blossom into a confident and loyal friend.What I Need In a Home:* Older children recommended*May prefer older, calmer dog friends*Would love a home that has slow feeders

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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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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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Mastiff puppies and dogs in Longmont, Colorado

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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.

Search for a Mastiff puppy or dog

Mastiff puppies and dogs in nearby cities

Related breeds in Longmont, Colorado

Mastiff shelters & rescues in Longmont, Colorado

Looking for a specific shelter or rescue?

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

Mastiff basics

Mastiff basics