Our offices in Listowel, Drayton, and Mount Forest will be closed on Saturday, October 7th and Monday October 9th for the Thanksgiving holiday weekend. We will reopen for business on Tuesday, October 10th. We will continue to provide 24-hour emergency services for our clients. In the event of a veterinary emergency please call 1-800-565-2047.

Large Animal Veterinarians

We are your partner in prevention, health, and performance.

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Meet the Team

Our Large Animal Vets

Dr. Daniella Rizzo


Daniella graduated from the Ontario Veterinary College in 2017; she joined the Heartland team shortly after completing the Summer Dairy Institute at Cornell University, a 6-week intensive training program for dairy veterinarians. She recently completed the Master of Public Health program at the University of Guelph and spends a portion of her time working as an epidemiologist with the Public Health Agency of Canada. Daniella grew up in a small town in the Niagara region, where she first developed a passion for working with large animals. Her main areas of interest include public health and the OneHealth initiative, emergency medicine, dairy production medicine, and bovine surgery.

Dr. John Thaler


John graduated from the Ontario Veterinary College in 2015. He joined the Heartland team in April 2016 after having practiced for 1 year as a large animal veterinarian. John has always had an interest in medicine, having completed a Master’s degree in human medical research on osteoporosis. His passion for veterinary medicine was ignited while working with camels, wild pigs, and other animals at the Calgary Zoo. His main areas of interest are bovine medicine and surgery, small ruminant (sheep & goat) medicine, and dairy herd problem-solving. Originally from New Hamburg, John now lives in Wellesley with his wife and their two pet chinchillas. In his spare time, he enjoys playing Ultimate Frisbee, board games, and whitewater kayaking.

Dr. Melanie Thompson


Melanie grew up in rural Flamborough near her grandparents’ dairy farm and began riding horses at a young age. She attended the University of Guelph for her undergraduate degree and graduated from the Ontario Veterinary College in 2018. During her time at the veterinary college, Melanie worked in the OVC Large Animal Clinic, which gained her lots of valuable experience in complicated cases. After graduating, Melanie worked in her hometown as a large animal veterinarian for her first year of practice. Melanie joined the large animal team at Heartland in 2019 for both food animal and equine practice. She enjoys ruminant medicine and surgery and working with farmers. Melanie also enjoys equine practice, with an interest in primary care, emergency care, and equine reproduction.In her free time, she enjoys running, riding horses, playing the piano and painting. Melanie lives in Drayton with her husband Will, and their cat “Mimi”.

Dr. Meredith Vair


Meredith grew up in the Annapolis Valley in Nova Scotia. She first gained an interest in large animal veterinary medicine while working at a local mixed practice. She obtained a BSc. Agr in Animal Science from the Nova Scotia Agricultural College and then went on to the Atlantic Veterinary College, where she focused her studies on equine and food animal medicine. Meredith joined the Heartland team in the spring of 2014 as a large animal veterinarian. Her main areas of interest are bovine surgery and dairy production medicine. In the future, she hopes to further expand her knowledge in dairy nutrition and calf health. Meredith lives in Listowel with her husband, daughter and son, and two dogs.

Dr. Niki Alsop


Niki is a recent grad from the Ontario Veterinary College in 2020. Niki comes from a family dairy farm in Feversham, where she spends much of her free time fostering her passion for agriculture and large animal medicine. She is excited to join the team at Heartland and to put her years of schooling to work. Niki has an interest in dairy production medicine. In the future, she looks forward to learning more about dairy nutrition and genetics.

Dr. Rod Wieringa


Rod graduated from the Ontario Veterinary College in 1994. After graduation, Rod practiced in Stratford for just over a year before moving to Listowel to work at Heartland Veterinary Services. Heartland’s large progressive dairy practice was the main attraction to move to Listowel. Shortly after arriving, Alton MacKay asked Rod to start flushing cows with him. Rod is a graduate of OVC’s Dairy Health Management Certificate Program and has a strong interest in embryo transfer technologies and dairy production medicine. What brings Rod the most satisfaction is being part of the next generation of veterinarians and staff as they develop their skills and help our clients achieve success. Rod lives in Listowel with his wife Lisa, and their two boys Matthew and Carter, and golden retriever Murray.

Dr. Thomas Veens


Thomas graduated from the Ontario Veterinary College in 2012 and immediately joined Heartland Veterinary Services to pursue a career as a farm animal practitioner specializing in dairy cattle. He became part owner in 2016. Thomas’ main focus is herd health, with a special interest in reproduction, calf and heifer rearing, transition cow management, disease prevention, and protocol development. In addition, Thomas works with bulls at artificial insemination centers and is part of the embryo transfer team at Heartland. Thomas is also very interested in surgery and enjoys performing many different surgical procedures. Thomas lives in Fordwich with his wife, Angelika, and children, Julia and Henry. He enjoys hiking, camping, canoeing, kayaking, various other sports, and traveling in his spare time.

Dr. Christie Morrow


Christie graduated from OVC in 2010, and her strong interest in dairy cattle medicine led her to Listowel upon graduation. After being away a few years, Christie rejoins the Heartland team to pursue her dairy production systems and embryo transfer passions. She completed the embryo transfer training course in Saskatoon with Dr. Reuben Mapletoft in 2013 and looked to explore all opportunities in this field. When not working, you can find Christie enjoying time with her family on their dairy farm with their dogs Lightning and Frankie. The Heartland management team excitedly welcomed Christie as co-owner in January of 2020.

Dr. Lisa Sharko

Lisa Sharko grew up in Oshawa, Ontario, before graduating veterinary school in 2014 from Szent Istvan University in Budapest, Hungary. After practicing for years as a large animal veterinarian, working primarily with dairy cattle in Southwestern Ontario, she joined the Heartland team in November 2021. Her main areas of interest include herd health management, calf health, and preventative medicine. Lisa lives near Hanover, Ontario, with her husband, Peter, and children, Ophelia and Patrick. In her free time, she spends a lot of time outside with her family, and she also enjoys crafting.

Dr. Laura Michalovic
Laura was born and raised in the suburbs of Montreal, Quebec and is fluent in English and French. She completed both her bachelor’s and master’s degrees at McGill University and went on to join the Heartland team after graduating from the Ontario Veterinary College in the spring of 2022 where she focused her studies on food animal medicine.

Her special interests include public health, food safety and emergency medicine. Laura loves travelling, playing volleyball, hiking, and painting. She also enjoys spending time with friends and family and with her black and white cat named Moomoo.

Dr. Brooke Galloway
Brooke graduated from the Ontario Veterinary College in 2022 and began working for Heartland after graduation. Before veterinary school, Brooke completed her diploma in Agriculture at Kemptville College and her Bachelor’s degree at the University of Guelph. Born and raised south of Ottawa, Brooke now calls Listowel home with her husband, Cole. You can find Brooke in the small animal clinic or on the farm, as her veterinary interests include small and large animal emergency medicine and surgery.

Brooke enjoys traveling, hiking, and spending time with her friends and family when she is not busy at work. Brooke and Cole also spend time working with their heifers under their prefix Goldline Genetics and share their home with their cat, Ellie.

Dr. Rich Devos

Rich Devos graduated from Centralia College in 1981 as an Animal Health Technician, the Ontario Veterinary College in 1991 as a Veterinarian, the Dairy Health Management Certificate Program in 2002 with Rod, and completed his Masters in Animal Welfare and Behavior in 2017. He ran his own practice in Drayton until 2022 at which time he semiretired and works part time for Heartland. His specialty is Dairy Health Management and Welfare. He married his College sweetheart Marilyn almost 38 years ago and along with her raised four boys, three of which are married and one engaged. His main passions are helping farmers reach their goals on dairy farms, serving in his church by helping people overcome mental health issues and spending time at the cottage.

Dr. Sonja Mulder

Bio coming soon!

Dr. Jesse Vandenberg

Jesse was raised on a dairy farm in Flamborough, Ontario, where he gained an interest in the dairy industry and a desire to become a dairy cattle veterinarian. He attended the Ontario Agriculture College before starting his studies at the Ontario Veterinary College. After graduating in the spring of 2023, he joined the Heartland team.

He has a particular interest in large animal surgery and herd health management, with a growing interest in dairy cattle nutrition. Outside of work, Jesse enjoys traveling, camping, hiking, and kayaking.