Sonja Tjostheim, DVM, DACVIM (Cardiology)

Department of Medical Sciences
Office: 4468

Sonja Tjostheim, DVM, DACVIM (Cardiology)

Titles and Education

    1. Diplomate ACVIM (Cardiology), 2017
    2. Cardiology residency, University of Wisconsin-School of Veterinary Medicine, 2014-2017
    3. Small animal medicine and surgery internship, VCA Canada CARE Centre, 2012-2013
    4. DVM, Western College of Veterinary Medicine, University of Saskatchewan, 2012
    5. BS, University of Toronto, 2005


Dr. Tjostheim’s primary research interest is the identification and treatment of arrhythmias in dogs and cats.


Currently, Dr. Tjostheim is a Clinical Assistant Professor of Cardiology for the Department of Medical Sciences. She teaches cardiovascular medicine to 3rd year students and clinical cardiology to 4th year students.

Clinical Interests

Dr. Tjostheim’s clinical interests include treatment strategies to achieve strict heart rate control in dogs with atrial fibrillation, identification and management of intermittent arrhythmias in dogs and cats using ambulatory ECG analysis and implantable loop recorders, and treatment of supraventricular tachycardias in dogs and cats.

Recent Publications

  1. Frantz EW, Tjostheim SS, Palumbo A, Kellihan HB, Stepien RL. A retrospective evaluation of the indications, complications and outcomes associated with epicardial pacemakers in 20 cats from a single institution. J Vet Cardiol 2021;36:89-98.
  2. Adin D, Freeman L, Stepien R, Rush JE, Tjostheim S, Kellihan H, Aherne M, Vereb M, Goldberg R. Effect of diet type on circulating taurine concentrations, cardiac biomarkers, and echocardiograms in four dog breeds. J Vet Intern Med 2021;35(2):771-779.
  3. Leblanc A, Atherton M, Bentley RT, Boudreau E, Burton J, Curran K, Dow S, Giuffrida M, Kellihan H, Mason N, Oblak M, Selmic L, Selting K, Singh A, Tjostheim S, Vail D, Weishaar K, Berger E, Rossmeisl Jr J, Mazcko C. Veterinary Cooperative Oncology Group – Common Terminology Criteria for Adverse Events (VCOG – CTCAE v2) Following Investigational Therapy in Dogs and Cats. Vet Comp Oncol 2021;19(2):311-352.
  4. Tjostheim SS, Kellihan HB, Grint KA, Stepien RL. Effect of sildenafil and pimobendan on intracardiac heartworm infections in four dogs. J Vet Cardiol 2019;23:96-103.
  5. Nadolny KE, Kellihan HB, Scansen BA, Tjostheim SS, Grint KA, Forrest LJ, Stepien RL. Cor triatriatum dexter in 17 dogs. J Vet Cardiol 2019;23:129-141.
  6. Martel-Arquette A, Tjostheim SS, Miller J, Carlson J, Mans C. Aortocavitary fistula secondary to vegetative endocarditis in a rabbit. J Vet Cardiol 2019;21:49-56.
  7. Tjostheim SS, Stepien RL, Markovic LE, Stein TJ. Effects of toceranib phosphate on systolic blood pressure and proteinuria in dogs. J Vet Intern Med 2016;30:951-957.
  8. Tjostheim SS, Kellihan HB, Csomos RA, McAnulty J, Steinberg H. Vascular hamartoma in the right ventricle of a dog: Diagnosis and treatment. J Vet Cardiol 2015;17:321-328.