
Internal Medicine
What we do
The Internal Medicine Service at New Bolton Center are internationally recognized specialists in large animal internal medicine. They diagnose and treat animals with medical problems including neurologic, respiratory, gastrointestinal, muscular, infectious, hematologic, renal and endocrine disorders. Board-certified dermatologists are available by appointment to consult on animals with skin problems.
Our Services
Disorders and Treatment
Endocrine diseases stem from imbalances in hormone levels. Endocrine diseases develop when the body produces too much hormone (hyper- diseases) or too little hormone (hypo-diseases). Examples include Equine Cushing’s Disease, Equine Metabolic Syndrome, and hypo- or hyper-thyroidism.
Diseases and disorders of the gastrointestinal system can often be life-threatening if not treated quickly. Problems such as colitis, gastric ulcers, and chronic inflammatory bowel disease can cause diarrhea, weight loss, or poor appetite. New Bolton Center offers the latest in diagnostic options, including gastroscopy, ultrasound, and intestinal absorption studies.
At New Bolton Center, we have the kind of foaling care you need, whether you are expecting a normal birth from a healthy mare, or if you are concerned about a high-risk foaling experience. Our combined expertise in equine internal medicine, reproduction, and neonatal intensive care means you can stop worrying.
Large animals can suffer from inherited or acquired muscle disorders such as Polysacharride Storage Myopathy, Rhabdomyolysis (“tying up”), and HYPP (hyperkalemic periodic paralysis).
New Bolton Center’s Neonatal Intensive Care Unit is designed to accommodate the special needs of critically ill neonatal patients.
Our board-certified neurologist, one of three in the US, focuses on diseases affecting the nervous system to which horses as well as camelids and food animals are susceptible.
Large animal kidneys are very efficient as long as they are in good health. Symptoms of kidney disease may be hard to detect without proper clinical care.
Every cell in an animal’s body depends on oxygen intake. Abnormalities can restrict oxygen delivery to the tissue, which affects performance and overall health. Our specialists diagnose and treat respiratory disorders such as pneumonia, pleuritis, and inflammatory or allergic airway diseases (“heaves”). It’s important to understand and treat disorders of the respiratory system in large animals quickly and effectively before they affect your animal’s overall health.
Our Care Team

Section Chief, Internal Medicine & Ophthalmology
Amy L. Johnson, DVM, DACVIM (LAIM & Neurology)
Professor of Medicine and Neurology; Marilyn M. Simpson Professor of Equine Medicine (CE)
Clinicians
Raymond W. Sweeney, VMD, DACVIM
Residents and Staff
Jessica Cathcart, DVM
Resident, Internal Medicine
Lawton (Leci) Irvin, DVM
Resident, Internal Medicine
Virginia Logue, DVM
Resident, Internal Medicine
Flavie Payette, DVM
Resident, Internal Medicine
Kavita Shroff, VMD
Resident, Internal Medicine
Kali Slavik, DVM
Resident, Internal Medicine
Hannah Taylor, VMD
Resident, Internal Medicine
Sarah Colmer, VMD, DACVIM
Neurology Fellow