Good training should make everyday life with your dog better.
At Diamond K9 Dog Training, Kati and Joyce help owners build clearer communication, more reliable behavior, and a relationship they can enjoy. Based in Biddeford, Maine, we work with families across Southern Maine, from people getting started with a puppy to owners who feel stuck with challenging behavior.
You can love your dog completely and still feel overwhelmed by their behavior. Our job is to help you understand what needs to change and give you the skills to move forward.
Meet Kati Peppe
Owner, Dog Trainer & Podcast Host
Before starting Diamond K9, Kati worked as a store manager at CVS. After leaving a long-term corporate career and becoming a mother, she began considering dog training as a new direction. Then a difficult Rottweiler puppy made the subject deeply personal.
Despite previous experience with the breed, Kati found herself dealing with serious biting, resource guarding, and behavior that made everyday life increasingly difficult. She sought help from trainers, followed their advice, and kept searching when the problems didn’t improve.
That experience shaped the trainer she became. Kati knows what it’s like to put in the work, spend the money, and still wonder why your dog isn’t getting better. It also taught her to look beyond whether a dog can perform commands during a lesson and focus instead on what actually happens at home, around distractions, and in everyday life.
Kati’s views on training developed through experience as well. She openly talks about once being wary of tools like prong collars before learning how they could be used appropriately. Today, e-collar training is an integral part of Diamond K9’s programs, alongside rewards, clear boundaries, and practical instruction for owners.
Her goal isn’t simply to produce a dog that listens to a trainer. It’s to give owners the understanding and skills to communicate clearly, follow through, and enjoy more of life with their dogs.
Today, Kati works with Southern Maine families on everything from puppy foundations and off-leash obedience to reactivity, resource guarding, and aggression. She also hosts Off Leash and Unfiltered, where she talks candidly about dog training, behavior, difficult cases, and the realities of living with dogs.
For Kati, some of the best moments come after the training itself: hearing from owners who can finally take their dog places, enjoy their home again, or simply feel confident handling situations that once seemed overwhelming.
Listen to Kati on Off Leash and Unfiltered
Meet Joyce
Dog Trainer · Composed Canine Private Training
Joyce works directly with owners through Composed Canine, our private training program focused on obedience, e-collar communication, and reliability around distractions.
Her sessions help owners learn how to teach their dogs what they want, communicate consistently, and address the overexcitement that can make it difficult for a dog to focus. The emphasis is on skills you can understand, practice, and use outside the lesson.
Composed Canine is an option for owners who want to learn alongside their dogs through private sessions. It is intended for dogs without serious behavioral issues or reactivity. For dogs with more complex needs, we’ll help you explore the other training options available.
Learn about Composed Canine and our other programs
Our Approach: Clear Communication, Consistent Expectations
We use a balanced approach to training: rewards to encourage desired behavior, clear boundaries, and corrections to address unwanted behavior. Depending on the dog and program, our methods may include slip leads, prong collars, and e-collars.
Tools are part of the process, not a substitute for teaching. We explain how we use them and why, and we want you to understand our approach before committing to a program.
We also pay attention to the individual dog. What motivates one dog may not motivate another, and the right training plan depends on more than a list of commands. The goal is clearer communication and a more manageable, enjoyable life together.
Read more about our training philosophy
Training That Continues Beyond the Session
Private sessions take place at our Biddeford training center. Our board-and-train programs use a normal home environment and include owner instruction to help you bring the training into your own household.
Your involvement matters in either format. Dogs are individuals, and progress depends on both the dog and consistent follow-through at home. We want you to understand how to maintain the training, recognize where things are getting off track, and use the support included with your program.
Read our frequently asked questions or hear from Diamond K9 clients.
Get to Know Us Before We Meet
You don’t have to wait for your first appointment to get a feel for us. The Off Leash and Unfiltered podcast covers training questions, case discussions, and the sometimes messy realities of life with dogs.
For a lighter conversation featuring both trainers, listen to Kati and Joyce on the weird, gross, and funny things dogs do. It’s a chance to hear us together and get to know the people behind the training.
You can also explore our dog training articles for more of the ideas and practical guidance we share with owners.
Let’s Talk About Your Dog
Tell us what’s happening, what you’ve tried, and what you’d like everyday life with your dog to look like. We’ll help you decide which training option is appropriate for your dog and your goals.
Diamond K9 Dog Training
432 Elm Street, Suite E
Biddeford, Maine 04005
Visits and private sessions by appointment.