Meet the Veterinarians & Staff of ZimmVet


Maria R. Krenz, DVM, Owner

Maria R. KrenzDr. Krenz has been practicing veterinary medicine in the Zimmerman area since 2007. She purchased ZimmVet in December 2008 after longtime owner and founder, Dr. Tony Damer, retired. She is passionate about providing the highest standard of care to companion pets in the form of new technology and updates to the clinic to better serve pets and clients.

Dr. Krenz holds a Doctorate of Veterinary Medicine from the University of Wisconsin-Madison and a bachelor of science degree in animal science from the University of Wisconsin-River Falls. She also regularly attends national and regional seminars, conferences, and workshops in order to stay up-to-date on the latest protocols and veterinary medical techniques.

Dr. Krenz lives on a hobby farm outside of Princeton with her husband, Josh, where they raise horses, cats, chickens, sheep, and cattle. In her spare time, she enjoys gardening and working on their farm and house.

Hillary McCulloh, DVM

Dr. McCulloh is a native of St. Cloud, Minn., and grew up on hobby farm where her family raised sheep and horses. Being a veterinarian was a lifelong dream, and a goal that began at the young age of 3. Dr. McCulloh graduated from the University of Minnesota College of Veterinary Medicine in 2006. After graduation, she traveled across the country and worked at several veterinary clinics, where she provided care for a number of different species in addition to dogs and cats. Dr. McCulloh also spent some time in the Western part of the United States, working for an animal shelter. She continues to be involved with various shelters and rescues presently.

Dr. McCulloh enjoys the diverse challenge of all aspects of general practice, but has a special interest in surgery with an emphasis on dentistry. Dr. McCulloh is constantly working to stay up-to-date on the latest veterinary medical information, and she frequently attends local and national continuing education workshops on various veterinary topics. Her favorite continuing education involves learning more about dentistry, especially hands-on dentistry wet labs where she practices the latest techniques and masters her dentistry skills.

When not at work, Dr. McCulloh continues to help her family with their sheep hobby farm. She also enjoys spending time outdoors hiking with her dogs, biking, cross country skiing, and riding her horses.

Stacy York, DVM

Dr. York holds a Doctorate of Veterinary Medicine from the University of Minnesota. After graduation, Dr. York has practiced small animal veterinary medicine in the Twin Cities area. Prior to becoming a veterinarian, Dr. York spent time learning about veterinary medicine by working as a kennel attendant, receptionist, technician assistant and veterinary technician. Dr. York enjoys being a general practitioner, and she has a very strong interest in surgical procedures.

Continuous education and learning is important to Dr. York and her ability to serve the individual needs of each patient. She accomplishes this by being an active member of the Minnesota Veterinary Medical Association, the American Veterinary Medical Association, the American Animal Hospital Association, and the Minnesota Veterinary Response team. In the past, she has also been a veterinary volunteer for RAGOM. She has also served as a foster home for Human Society's Orphaned kitten project. Dr. York is also a former member and foster parent for Second Chance St. Bernard Rescue and past member of Northstar Newfoundland Club.

Having been born and raised on a small beef cattle farm in Iowa, Dr. York enjoyed the opportunities to work with a wide range of animals growing up. Today, Dr. York lives in the Twin Cities with her husband, Mike and their two children. She also has two domestic long-haired cats, and three dogs (Chewy - Newfoundland, Dozer - English bulldog, and Lulu Belle - French bulldog). In her spare time, Dr. York aspires to enjoy photography, scrap booking, hiking, biking, boating, cooking, reading, and working on home improvement projects with her husband.

Technician Staff

Kelly Melhorn, CVT

Kelly MelhornKelly was born and raised in Minnesota and began to express her career passion for animals in 2000. She received a Bachelor's degree in Biology from Bemidji State University and used her degree to become a zoo keeper. She worked as a zoo keeper for over 4 years at the Red River Zoo in Fargo, North Dakota. During that time, she was able to help raise a pack of wolf pups and a litter of porcupines. Kelly was also the only zoo keeper in the U.S. to breed Russian Red Tree Squirrels and raise them.

In 2011, Kelly and her husband were looking for a change of scenery and moved to Colorado. She decided to further her education and enrolled at the Bel-Rea School of Animal Technology to become a Certified Veterinary Technician.

In 2014, Kelly moved back to Minnesota and now lives in Otsego with her husband Josh, their daughter Clara, their two dogs Kramer and Clarence, and three cats Cleopatra, Gunther, and Matilda.

Kristin Rinkel, CVT

Kristin RinkelWith over 9 years of experience, Kristin chose to be a professional veterinary technician because of her compassion for helping pet owners understand the health needs of their loved ones. This compassion can be seen in how she approaches every individual pet.

Kristin began her career by fulfilling a variety of veterinary clinic roles, including working as a veterinary assistant, receptionist and kennel worker. In 2009, Kristin graduated from the Minnesota School of Business with an Associates of Science Degree in Veterinary Technology. Today, Kristin is a Certified Veterinary Technician.

Having a father in the U.S. Army, Kristin was born in Germany and spent many of her younger years overseas and in other parts of the U.S. She spent the remaining parts of her childhood and young adult life in Minnesota. Kristin currently lives in Princeton with her husband Jake, and their infant daughter, Autumn, as well as their furry friends Pumpkin (cat) and Kiya (Siberian Husky).

Ashley Middendorf, CVT

Growing up as a child, Ashley's passion for veterinary medicine was greatly influenced by close family and friends with careers in the veterinary field. She would spend the summers while growing up in Wisconsin at her Aunt's veterinary clinic, which allowed her to observe the veterinary field in action. These experiences encouraged her to pursue a career in veterinary medicine.

After high school, Ashley pursued her passion for animals by attending the University of Minnesota for animal science. During this time, she decided to pursue the veterinary technician career path. She transferred to Minnesota School of Business and graduated with her Associates of Science Degree in Veterinary Technology in 2010. As a Certified Veterinary Technician, one of her first jobs was as a veterinary technician at a humane society. She enjoys continuing her education with conferences, and being an active member of Minnesota Association of Veterinary Technicians.

Ashley resides in Big Lake Township with her husband, Chris. They share their home with four dogs & 2 cats.

Support Staff

Amy Johnson, CVT, Lead Customer Service Representative

Amy JohnsonAmy started her career in veterinary medicine in 1993, and now serves as the lead receptionist for ZimmVet. She holds an Associate of Science Degree from the Medical Institute of MN, Veterinary Technology Program. Amy enjoys veterinary medicine because it is an ever-changing and challenging profession. Her career choice also fuels her passion for animals by providing pets with a positive medical experience every day.

A certified veterinary technician, Amy uses her 20 years of experience to help customers understand the services offered by the clinic. This firsthand veterinary technician experience gives her an in-depth perspective when discussing services performed on our client's pets.

Amy resides in Milaca, Minn., with her husband and their many animals. She enjoys spending time with her many varied animals and working on outdoor projects.

Pam Shafer, CPDT-KA (Certified Professional Dog Trainer - Knowledge Assessed)

Pam SchaferPam leads the Pet Boarding, Doggie Daycare and Behavioral Pet Training Classes at ZimmVet. A lifelong animal enthusiast, Pam has a tremendous passion for learning and teaching animal behavior. Pam began her career as a veterinary technician assistant in 2006. Shortly after beginning her career, she began managing a Doggie Daycare and Boarding facility.

In 2014, Pam became a certified dog obedience trainer. Over her career, she has continuously studied canine body language, behavior, and training through positive reinforcement. Pam enjoys helping owners connect and bond with their pets by helping owners teach their pets proper manners and fun tricks.

Pam leverages her knowledge of animal behavior when working with Doggie Daycare and Boarding pets as well. She uses this time to study the behaviors and characteristics of positive reinforcement, which she can then pass on to the pet's owners. Pam lives in Anoka with her family and their two dogs, Ranger and Riley, and two cats, Steve and Kevyn. She has two daughters and is expecting her first grandchild, soon.

Stephanie Mistretta

Stephanie has been an avid animal lover her entire life. She grew up with many canines around her house, including Alaskan Malumutes, American Eskimos and Golden Retrievers. In addition, she expressed her love for dogs by volunteering for a local Golden Retriever rescue for ten years, during her youth.

With more than 10 years of customer service support, Stephanie works with customers to listen to their needs and to help them in each unique situation. Her pet care career began in 2007 and includes past experiences at a boarding and grooming facility as well as a 24-hour animal hospital. Combining her customer service experience and pet care experience, helps Stephanie provide personalized pet care to every patient.

A St. Louis, Mo., native, Stephanie now resides in Foreston, Minn., with her boyfriend Randy and their two cats (Mila and Lola) as well as their Golden Retriever (Seger). In her spare time, she plays softball and enjoys attending St. Louis Cardinals and St. Louis Blues games as well as traveling to NASCAR races.

Client Testimonials

I really appreciated the way the doctors at the clinic cared for Diamond. Over fifteen years of love with my wonderful dog and the quality of regular care she received at the clinic made it possible. I was especially touched by the sympathy card I receive after sadly having to put her to sleep, it shows they really care.

— Darryl Anton

After recently moving to Minnesota we researched many veterinarian options and we chose the Zimmerman Veterinary Clinic. The staff was honest, thorough and genuinely caring. Their follow-up on our pets care was outstanding. Itís worth the trip for your petís care.

— The Connorsí Family - Rich & Amy Maximus, Petie, Buster, Bandit, Shadow, Kodibear & Sammy

We have taken our pets to the Zimmerman Vet Clinic for 20 years. Even when our visit was a sad one, we were treated with kindness and courtesy. The staff has always been professional and friendly. We highly recommend Zimmerman Vet Clinic to anyone who loves their pet.

— Bratsch

The staff at Zimmerman Veterinary Clinic has taken care of my dogs since 1979. I am especially pleased with the care of my last companion/friend, Ruby Mae. She received the best care I could have expected. The staff gave her loving care and attention during her whole lifetime. I canít thank them enough for being there for support. I will continue to use them with my new friend, Baily Sue.

— Sincerely, Dale Cannon

We love Zimmerman Vet! They give the best care & have a wonderful staff!

— Laurie Gansen Cramer

Thank you all for being such amazing people & taking such great care of my little man Bentlee! You will never know how much I appreciate all your information, fast actions & the care you put forth to all animals that come to your office! Thanks Again!

— Dani George

Iíve had dogs all my life and this is by far the best place to take your pet for their veterinary needs!!! Great service from the entire staff, they really care about the wellness of your pet, and my Gauge gets a little extra TLC (he is a senior now).

— Bonni Placek Cook