Meet The Doctors


Dr. Nathan Hein

Nathan Hein, DVM was born and raised in Eastern Iowa.  Nathan garnered both his undergraduate and veterinary degrees from Iowa State graduating from the College of Veterinary Medicine in 2004. Nathan then completed an internship program and practiced as an associate veterinarian in Houston, Texas prior to moving back to Iowa. 

Nathan and his wife Joanna took ownership of Heartland Animal Hospital in October of 2010.  With great support from the community of Marion, the hospital grew to a point where it needed more space to meet the needs of its growing client base.  In 2015, he led the construction of the new hospital at its current location.

Dr. Hein's professional interests include ophthalmology, diagnostic imaging (radiology and ultrasonography), dental care, and surgery.  Nathan continues to pursue on-going education in dental care and ultrasound to enhance the hospital’s service in these two areas. 

He enjoys golfing, triathlons, and spending time with his family. A great passion of Nathan’s is supporting and attending Iowa State University football and basketball games with his family. 


Dr. Joanna Mangold

Dr. Joanna Mangold, owner of Heartland Animal Hospital, is from Eastern Iowa and graduated from Iowa State University, College of Veterinary Medicine in 2004. After graduation, Joanna moved to Phoenix, Arizona to complete her veterinary internship. Upon completion of her internship she moved to Houston, Texas and practiced Veterinary Medicine there for 5 years. Joanna has a special interest in dermatology and exotic pet care. Joanna sees all of Heartland Animal Hospital's exotic pet patients on Wednesdays, by appointment only.  In her spare time, she teaches dance at Dance Academy of Cedar Rapids and is a member of Junior League of Cedar Rapids. She enjoys reading and traveling. 

Dr. Catherine McMillan

Dr. Catherine McMillan is from Eastern Iowa and graduated from Ross University School of Veterinary Medicine in 2014.  After graduation, Catherine moved to Cincinnati to begin her veterinary career. She decided after 1 ½ years that her heart was calling her back to Iowa. Catherine has the pleasure of serving her two 18 year old cats, Sarah and Ciggi, a shih tzu named Timmy, a poodle mix named Nala, and a standard poodle named Mirabell.   Catherine has a special interest in low stress handling, felines and dentistry.  


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