photo of flyer for ventricular septal defects in arabian horses

Select for larger image

Below, please find links to all of the clinical trials involving cardiology. The studies include a multitude of information, including (but not limited to) the study’s purpose, benefits for participating, and financial incentive information. If you have any questions, please contact the individual outlined at the end of each trial summary.

Please visit the Cardiology service webpage at the Veterinary Medical Teaching Hospital (VMTH) if you would like to learn more about the amazing things that our veterinarians can do for you and your animal.

Horses & Ponies

Ventricular Septal Defects in Arabian Horses: Identifying the Genetics

Title: Equine Ventricular Septal Defects

Purpose of Study: Ventricular Septal Defects (VSDs) are the most common congenital heart defects in horses. They allow blood to shunt inappropriately from the left ventricle to the right ventricle via an opening in the ventricular septum. This blood recirculates through the lungs and left chambers, resulting in enlargement of these structures. Arabian horses are overrepresented in horses presenting for VSDs, and we are investigating the possibility of a genetic predisposition for this defect.

Contact: Eric Ontiveros, Stern Laboratory Coordinator: ( or 530-752-4892)

Participation Requirements: Arabian horses or Arabian crosses that have a right-sided systolic heart murmur, or a veterinary diagnosis of VSD. Horses must tolerate handling and stand for the echocardiogram.

Initial Evaluation for Participation: None.

Procedures: Collection and submission of a blood sample (3ml in an EDTA purple top) for DNA extraction by the cardiac genetics laboratory

Benefits: Results from this study will determine if a genetic factor plays a role in the development of Ventricular Septal Defects in Arabian horses. This finding would have great significance regarding screening predisposed horses and hopefully guiding breeding management to avoid continuation of this defect in the Arabian horse.

Owner Responsibilities:

  • Submission of a blood sample either by you or the referring veterinarian
  • If your Arabian was diagnosed with a heart murmur but you are unsure whether it qualifies for the study, please contact us. In some cases, we may be able to review your horse's medical records or even fund a cardiac examination for your horse.

Printable Flyer (PDF)


Hypertrophic Cardiomyopathy: Assessing a Treatment

Title: Short-term effects of pimobendan in cats with hypertrophic cardiomyopathy

Purpose of Study: Hypertrophic cardiomyopathy (HCM) is the most common heart disease in cats and we do not have a good understanding of how to best treat this devastating disease. One drug, pimobendan, has been shown to have significant clinical benefits in cats with HCM, but more studies are needed to evaluate exactly how this drug affects heart function. The purpose of this clinical trial is to evaluate the effects of pimobendan on heart function in cats affected with HCM, which will help us make with better treatment recommendations for cats with this disease.

Contact: for questions related to enrollment and scheduling

Participation Requirements:

  • Cats with suspected or diagnosed HCM, including cats with heart murmurs, a diagnosis of congestive heart failure, or elevated NT-ProBNP on bloodwork (>100pmol/L)
  • Ineligible cats are those that:
    • Are on certain types of medications that affect heart function (If your cat is receiving medications for his/her heart, please contact us because he/she may still be eligible).
    • Have an identifiable systemic disease or high blood pressure
    • Have abnormally fast or slow heart rhythms
    • Have blood clots within their hearts
    • Cannot tolerate handling without sedation for echocardiographic assessment, which involves your cat laying on his/her side for approximately 20 minutes

Initial Evaluation for Participation: A complete cardiology work-up will be performed, including a cardiovascular exam, cardiac ultrasound, blood pressure measurement, thyroid hormone analysis (if >6 years old), and blood sample analysis for kidney values and electrolyte assessment. A sample of blood will also be saved for cardiac biomarker measurement and future genetic analysis.

Procedures: If your cat is deemed eligible by our initial evaluation and if you agree to let your cat participate in this study, the following will happen:

  • Visit 1
    • A cardiovascular examination, blood pressure assessment, and echocardiogram before and one to two hours following administration of a single, standard oral dose of pimobendan
    • Completion of a brief questionnaire
    • Random assignment to a group to receive either placebo or pimobendan by mouth twice daily (every 12-hours) for 1 week at home
  • Visit 2 (1 week after group assignment)
    • A repeat cardiovascular exam, blood pressure assessment, blood collection, and echocardiogram
    • Completion of a brief questionnaire

Benefits: The study will cover a significant portion of the costs (. Your cat will receive a full cardiology evaluation that your family veterinarian can use to assess your cat’s cardiac health (including cardiac ultrasound, blood work, and blood pressure analysis).

Results of the study will help us better understand how pimobendan works in cats and will help us learn how to use it best to help our cat patients with heart disease. This study could greatly affect how we treat heart disease in cats, and could greatly help cats with heart disease.

Owner Responsibilities:

  • Covering the cost of a discounted cardiovascular evaluation and cardiac ultrasound
  • Administering either pimobendan/placebo to your cat twice daily for 7 days, until re-evaluation
  • Monitoring your cat closely for health changes at home
  • Bringing your cat back to the UC Davis Cardiology Service in approximately 1 week for re-evaluation
  • Completion of a questionnaire about your cat’s health at the first and last visit

If the cardiologist recommends that your cat have additional tests or treatments that are not part of the study, you would be responsible for the additional fees as discussed and authorized during the visit.

Printable Flyer (PDF)


Subvalvular Aortic Stenosis: Understanding the Genetics in Bullmastiffs

Title: Genetic Investigation of Subvalvular Aortic Stenosis in Bullmastiffs

Purpose: Subvalvular aortic stenosis (SAS) is the second most common heart defect diagnosed in dogs, and the Bullmastiff breed is over-represented in incidence of SAS. Moderate and severely affected cases are at risk for developing severe cardiac complications, and have an average lifespan of 19 months. Furthermore, there is no surgical treatment available that results in an increased life expectancy for affected cases. The aim of this study is to identify genes/variants associated with SAS in Bullmastiffs that can be used to develop a genetic test.


Participation Requirements:

  • Bullmastiffs that have been diagnosed with SAS; or
  • Parents and/or littermates of dogs with SAS

Initial Evaluation for Participation: None.


  • If you decide to enroll your dog in this clinical trial, an echocardiogram performed by a board certified cardiologist is required.
  • Collection and submission of 2-3ml of whole blood by the owner or a veterinarian

Benefits: Results from this study can be utilized to produce an SAS genetic test for Bullmastiff. A genetic test can be used to screen predispose Bullmastiffs and guide breeding practices to reduce disease prevalence in this breed.

Owner Responsibilities: Submission of the following items:

  • 2-3ml of whole blood
  • A copy of the 3-generation pedigree (if available)
  • A copy of the veterinary report
  • Filled out enrollment form (contact Dr. Stern or Eric Ontiveros for this form)

Printable Flyer (PDF)

Atrial Fibrillation: Understanding the Genetics in Irish Wolfhounds

Title: Genetic Determinants of Atrial Fibrillation in Irish Wolfhounds

Purpose: Atrial fibrillation (AF) is an arrhythmia in which the heart beats fast with no identifiable pattern of atrial activation. Although AF affects a wide variety of animals, it has a particularly high prevalence in Irish Wolfhounds suggesting a genetic predisposition. We are conducting a genetic investigation into the cause of AF in Irish Wolfhounds in order to improve our understanding of this disease and thus inform prevention and treatment practices.


Participation Requirements:

  • Irish Wolfhounds that are older than 8 years old with or without atrial fibrillation
  • If your Irish Wolfhound has already had a completed cardiology evaluation (exam, echocardiogram and EKG), you may be able to participate by simple submission of a blood sample.

Initial Evaluation for Participation: None.

Procedures: If you agree to let your dog participate in this study, the following will happen:

  • Complete cardiology evaluation, including a focused cardiovascular physical examination, an electrocardiogram (non-invasive measure of heart rhythm), and an echocardiogram (heart ultrasound) without the use of sedatives to determine if atrial fibrillation and/or other cardiac diseases are present.
  • Blood collection for DNA extraction, which will be used for the genetic analysis of atrial fibrillation

Benefits: All costs associated with the study will be paid for by the study. Adverse effects are not expected from a cardiac screening; however, if adverse events occur directly as a result of the study and your dog requires further care (e.g. hospitalization, monitoring, treatment/medications etc.), the study will cover up to $3,000 of your dog’s care.

Identification of genes will allow us to better understand and guide medical care for your dog and future dogs affected with atrial fibrillation.

Owner Responsibilities: If you allow your dog to participate in this study, you will be responsible for coordinating a scheduled visit with the laboratory and bringing your dog to the scheduled appointment. Participants are responsible for paying any costs incurred that are not related to the study. The study appointment and procedures are anticipated to take approximately 2 hours and will consist of a single visit.

Printable Flyer (PDF)

Irregular Heartbeat (Ventricular Arrhythmias): Reducing the Risk during Chemotherapy

Title: Use of diphenhydramine to reduced fewer infusion-related ventricular arrhythmias in dogs treated with doxorubicin

Purpose: The current recommendation for canine lymphoma treatment includes the use of a chemotherapy drug called doxorubicin. Although effective, one of the reported side effects of doxorubicin is the liberation of a molecule called histamine, which can cause ventricular arrhythmias (an irregular rhythm). The concurrent use of anti-histamine agents like diphenhydramine (commonly known as Benadryl) with doxorubicin therapy could possibly reduce these abnormal beats. Therefore, the aim of this study is to see if use of diphenhydramine can reduce the risk of arrhythmias sometimes associated with the administration of chemotherapy.


Participation Requirements: Dogs that have been diagnosed with lymphoma

Initial Evaluation for Participation:  None.


  • As part of this study, your animal will receive the same diagnostic tests and care that any other dog presented to the Oncology Service would receive. If your dog participated, an anti-histamine drug (diphenhydramine) will be given at only one out of the two study visits.
  • If your dog participated, an anti-histamine drug (diphenhydramine) will be given at only one out of the two study visits.
  • To evaluate the efficacy of diphenhydramine, your dog will wear a portable and battery-operated device that measures heart's activity (Holter monitor) for 3 hours after the infusion of chemotherapy while your dog is still at the VMTH.

Benefits: If you agree to have your dog participate in this study, the screening echocardiogram and your dog’s Holter monitor will be analyzed by a board-certified veterinary cardiologist and will be free of charge. Adverse events are not expected from the use of diphenhydramine; the study will cover up to $3,000 of your dog’s care if any adverse events occur that are attributable to the investigational portion of the study (use of diphenhydramine or not as a pre-medication for doxorubicin) and your dog requires further care (e.g., hospitalization).

Results from this trial may help us to better guide medical care for your dog and future dogs affected with the same disease. The understanding of your dog’s electrocardiogram may guide medical decisions.

Owner Responsibilities: We expect that participation in this clinical trial will last for two visits of the traditional CHOP chemotherapy protocol.

Costs associated with the recommended chemotherapy protocol and patient care will be your responsibility as they are not a part of this study. Additionally, costs associated with side effects that are attributable to doxorubicin administration (decreased appetite, vomiting, diarrhea and/or low white blood cells counts) will not be covered by the study.

Printable Flyer (PDF)

If you cannot find what you are looking for, please email us or call (530) 752-5366.