Diagnostic accuracy of heart murmurs in small breed dogs

Purpose

To provide novel data about the diagnostic accuracy of radiographic measurements for identifying dogs with ACVIM Stage 2 MMVD when performed soley by primary care practitioners in a population of dogs in which the cause of their murmur is unknown.

Background

• Myxomatous mitral valve disease (MMVD) is the most common acquired heart disease affecting dogs. 
•  This disease occurs in adult dogs with increasing frequency as the dog ages and is particularly common in smaller breed dogs.
• More than 90% of high-risk small breed dogs greater than 10 years of age are affected.
• MMVD can progress to congestive heart failure impacting both the pet’s quality of life and survival. The current American College of Veterinary Internal Medicine (ACVIM) consensus statement for management and treatment of MMVD in dogs recommends staging MMVD to help guide treatment decisions.
• Asymptomatic dogs with heart enlargement meeting specific clinical, radiographic, and echocardiographic criteria are classified as stage B2 MMVD and are expected to benefit from medical therapy. Treatment benefits reported for stage B2 MMVD include up to a 15-month delay in the onset of congestive heart failure and slower progression or even improvement in heart enlargement.
•  Despite the benefits of early medical intervention, many dogs do not receive this care because they don’t have access to the necessary testing. 
• The cost of diagnostic testing (physical exam, thoracic radiographs, and echocardiography) to determine the cause of the murmur, identify dogs with MMVD and determine if they meet ACVIM criteria for treatment in our cardiology service has a client cost of $650, and in other academic institutions and referral specialty practices often exceeds $1,000.
• Patient care could be improved if there were reliable alternative approaches that the primary care practitioner could take for asymptomatic dogs with a heart murmur when echocardiography could not be pursued.

Eligibility

• Dogs that are over 4 years of age
• Dogs that are less than 20 kg (44lbs)
• Dogs that are asymptomatic for cardiac disease 

Exclusion Criteria

• Dogs less than 4 years of age
• Dogs weighing more than 20kg (44lbs)
• Dogs with a persistent cough
• Dogs with increased respiratory rate and/or effort

Study Design

This is a pilot study to evaluate the relationship between sleep and pain. First, we will ask owners to complete a survey about their dog’s sleep habits and any signs of pain. This information will be used to invite some dogs for in person visits. If your pet is selected for an in person visit, we will ask you for some additional information, we will also examine your pet to make sure they are a good study candidate. We will ask you to leave them overnight for a video recording of their behavior and then a sleep study where they will wear a harness, and electrodes will be placed temporarily under the skin so that we can measure their sleep. The next day, dogs will be placed under anesthesia and an MRI will be performed. Small skin biopsies may also be collected. After recovery from anesthesia, your dog will be discharged. If your dog is considered painful, we may prescribe pain medications.

Funded by:

The Stanton Foundation