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About Us

Welcome and thank you for visiting The Happy K-9 where we focus on Real world dog training with Real world distractions. We train dog owners and rehabilitate/educate dogs. We especially deal with owners that struggle with dog aggressive and or human aggressive dogs. We welcome you and never believe that hope is lost because change is always possible with proper tools and information. Give a dog a leader and they'll thank you with loyalty and companionship. See our testimonial page to see what our clients have to say!

What We Are

With so many families struggling with even the basics of dog obedience, this page is a breath of fresh air that shows the results and the training of real world dog training. I am a results oriented dog trainer and work any tools and techniques that get those results. So many families have gone to 6-12 even 18 weeks of dog training and still not even gotten the basics down. It is not supposed to be like that and I offer folks an alternative. For more of an insight of who are and to get a better feel for how we run things please visit our facebook page.

About The Owner

My name is Nelson Mendoza and I am a Dog Obedience and Behavior Modification dog trainer and dog behavioralist. Here at The Happy K-9, we train dog owners and rehabilitate/educate dogs. We have trained hand in hand with the two top dog trainer in the east and west coast, with Sean O’ Shea, owner of The Good Dog in California and who is also one of Cesar Millan’s personal hired trainers in Cesar’s “highly-acclaimed seminar ‘Training Cesars Way’”. On the East Coast we have trained with Jeff Gellman, owner of ‘Solid K-9 Training’ who has many awards for the best board and train facility and is very well known for rehabilitating dogs that are marked ‘red zone’, overall a fantastic man and dog trainer/behavioralist. I made my way up to Nova Scotia, Canada for a shadow program with Ted Efthdyimiadis from Mango Dogs one of the best trainers in the industry dealing with rehabilitating dogs with real genetic aggression, dog aggression, human aggression, resource guarding, etc.

We have trained with the best which is why is we give people the best results.


I am a “Real-World” dog trainer, who will work with your dog in real-life situations. It is highly unlikely that there will come a point in time when your dog is at the dog park with tons of dogs running, playing, and wrestling around them and they will be sitting waiting for you to call them, it rarely happens, which is why it is important to have a dog that has 100% off-leash recall abilities no matter how high the distraction is. Your dog might lie down on command or sit on command and “stay” at home but not when distracted by kids running around, ambulances driving by, baby strollers rolling by, or other dogs barking and lunging at them. Your dog should do a solid “down/stay” AND a solid “sit/stay” until you give another command, with no problem. Most dogs are born to be followers but the big mistake most people make is when they humanize the dog, which gives them that role of authority and they begin to become leader and telling YOU what to do. If you treat your dog like a kind/Queen, don’t be surprised when they set rules for THEIR kingdom. Because we deal with a lot of aggressive dogs, I have incredible structure in my training. Some people might find my training extreme, but when your dog is chasing a squirrel and heading into the street, do you want your dog to respond to you only 50% or 75% of the time or listen to you 100% of the time? Remember, too, that I do not attempt to take the playfulness out of your dog. Play is important, at appropriate times and places. We incorporate in our training rules, boundaries and limitations which betters the dog understanding of becoming a follower and understanding there is a time and place for everything.


Pet CPR and First Aid Certified by AAVSB
International Association of Canine Professionals (IACP)
Association of Professional Dog Trainers (APDT)
Train the Trainers Workshop Completion

Services and Pricing

All dogs respond to a balanced training program no matter what the breed, age, or previous history. Dog Breed is not an excuse for bad behavior! If you have heard this from other trainers, it could be an excuse for their bad training system.

Board and Play Program

Pet owners choose doggy daycare because after a day in daycare, your pet is less anxious, stressed or demanding of you after you’ve put in a hard day at work. A happy pet makes for a happy pet owner! Late pick-up options are available.

General Information

- The Happy K-9 Kennel operates by appointment between the hours of 7A.M. – 6P.M. The kennel is open on Sunday and all legal holidays also by appointment only. (We may make off-hour exceptions for drop-off or pick-up, at our discretion.)

- One week advance notice required for boarding.

- We require emergency telephone numbers including the telephone number of the pet’s veterinarian and personal contact information.

- If a pet becomes seriously ill every attempt will be made to contact you. If your pet’s health demands quick action a call will be made to the pet’s veterinarian or, if necessary, to another veterinarian. All veterinarian expenses are the responsibility of the owner.

- All dogs must be leashed upon arrival on the property. We enforce leashing because there are designated areas to potty, which promotes good hygiene and helps control odors. If possible, please allow your dog to eliminate prior to arrival.

- No leashes or collars are to be left with your pet. We are not responsible for leashes, toys, etc.

- Every precaution will be taken while caring for your pet, however, all risks are assumed by the pet owner.

- Fence fighting or excessive barking will be controlled and or eliminated.

- Most daycares will not take aggressive dogs because it is a HUGE liability but with our staffs expertise with dealing with aggressive dogs this is not a problem. (human aggressive dogs will be evaluated prior to acceptance)



- Vaccinations: Proof of current vaccinations for rabies, distemper and kennel cough must be provided prior to boarding.
- Food is to be supplied by Pet Owner and staff is to be informed if pet requires a special diet.
- Medicine will be administered as prescribed
- We ACCEPT ANY DOG, ANY BREED, ANY SIZE, ANY AGE, ANY SITUATION! (dog aggressive, toy aggressive, food aggressive, even human aggressive (decision made upon evaluation) )


The Happy K-9 training services in are Somerville, Medford, Cambridge, Malden, Everett, Woburn, Stoneham, Revere, Arlington, Belmont, Wakefield, Danvers, Saugus, Peabody, Dorchester, Boston, North end, South end, Haverhill, Wilmington, Billerica, and Chelsea. If your city is not on this list give us a call and we will let you know what we can work out and if too far for travel we can refer other trainers in your area that WE have personally worked with.

Do you have any questions? Get in touch!

Call us at: 617-501-0832

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