Say your horse has a fever of unknown origin and your veterinarian has exhausted his resources trying to pinpoint the cause. Or, maybe your horse is showing neurologic signs and your vet is looking for a peer’s input to aid in diagnosis and treatment. At that point, your general equine practitioner might contact or refer to a veterinary internal medicine specialist certified with the American College of Veterinary Internal Medicine (ACVIM).

The ACVIM formed in 1972 as a national certifying organization of veterinary medicine specialists in cardiology, large animal internal medicine, neurology, oncology, and small animal internal medicine. Becoming ACVIM-certified generally requires four additional years of study and experience (internship and residency) after a practitioner graduates from veterinary school, as well as two intensive exams, publication requirements, and career-long continuing education.

“I think there’s sometimes confusion in the difference between and ‘internist’ and an ‘intern,’” said Sarah Reuss, VMD, Dipl. ACVIM, who serves on the ACVIM’s marketing committee and works at the University of Florida College of Veterinary Medicine. “An ‘intern’ is someone who just graduated from veterinary school. An ‘internist,’ or an ‘internal medicine specialist,’ is someone who’s completed all their internal medicine training and certification.”

Internal medicine specialist see cases ranging from common infectious diseases to complex, multisystem conditions, Reuss added. They are also frequently involved in research and see cases involving rare and emerging diseases.

The ACVIM has more than 2,000 members and is the largest organization of board-certified veterinary specialists in the United States. For more information or to locate an internal medicine specialist in your area, visit

About the Author

Michelle N. Anderson, Digital Managing Editor

Michelle Anderson serves as The Horse's digital managing editor. In her role, she produces content for our web site and hosts our live events, including Ask the Vet Live. A lifelong horse owner, Anderson competes in dressage and enjoys trail riding. She's a Washington State University graduate (Go Cougs!) and holds a bachelor's degree in communications with a minor in business administration and extensive coursework in animal sciences. She has worked in equine publishing since 1998. She currently lives with her husband on a small horse property in Central Oregon.

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