Who We Are

We are a small, privately-owned rural veterinary clinic with a focus and dedication to creating and maintaining a close, accessible and familial relationship with you and your pet.

Our History

Practice owners and brothers, Aaron and Ira McCauley, both graduated from University of Missouri veterinary school. After working at various veterinary clinics in Missouri, they purchased New Melle Animal Hospital in the Defiance, MO area in 2000.  In 2001, the McCauley brothers opened McCauley Animal Clinic in Weldon Spring off Highway 94 to further expand their services in the St. Charles County area.  New construction began March 2016, and the McCauley Animal Clinic is now relocated to 4646 Mid Rivers Mall Drive in Cottleville. We enjoy providing veterinary services to clients in Defiance, Washington, Lake St.Louis, O' Fallon, and Wentzville. 
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Dr. Ira and Dr. Aaron

​Associate veterinarian, Megan Wilson, joined the New Melle practice in July 2018.  The vets and staff at New Melle Animal Hospital continue to enjoy offering the "hometown vet" feel and care for our little community.

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Dr. Megan

What Our Clients Are Saying


"I always feel that my pets are well cared for when they visit the vets and staff at New Melle Animal Hospital. The staff recognizes me and my pets, knows their history, and are truly concerned about their welfare."  Lisa

"NMAH has been taking care of our pets since we moved out here in 2000. The staff has always treated us with the utmost respect, providing us with the best possible care for our pets, & giving us recommendations when necessary to see specialists."  Sandy

"My husband brought our puppy in to get a couple of shots. He has never been to this vet before and he was very impressed. He was happy with the service and how our puppy was cared for."  Anonymous

"Aaron McCauley took time to explain in detail his thoughts related to my older dog's difficulty walking. The discussion was extremely interesting and useful. It was refreshing to see a Dr who was willing to spend time explaining the situation."  Anonymous

​"Friendly and caring staff, upfront and straight forward about costs and needs for my pets and great availability! " Samantha

"I love you guys! You are all so friendly and caring and are very reasonable in your fees. I pass at least 5 other vets on my way to see you guys. You are the best."  Michelle

"Super friendly staff, that explain things fully!"  JD and Hope

"You guys Rock! I have a healthy, happy Dachshund friend again. TY!"  Donna

​"They always take care of our three pooches! They do their best to get us in as quickly as possible and always show how much they care about our pets. So glad we have them in our little rural community."  Tammy