Direct HR: 100 beats/min
Heart rhythm: Regular
Intensity of heart sound: Normal
Extra sounds – clicks or gallops: None
Precordial palpation: Normal
Lung sounds: Normal lung sounds in all fields
Cardiac auscultation: Auscultation over the left apex revealed the following sounds which radiated well to the right hemithorax

The CEG considers the following differential diagnosis as most likely (and why): MMVD is a very common disease in older small breed dogs (especially common in Cavalier King Charles Spaniels) with left apical systolic heart murmurs (characteristic of mitral reguritation).

The CEG considers the following diagnostic tests as the highest priority: In an apparently healthy/asymptomatic small breed, older dogs with a heart murmur consistent with mitral regurgitation and therefore a presumptive diagnosis of MMVD, the CEG considers evaluation of heart size to be the highest priority. Heart size can be used to determine if the dog would benefit from the initiation of pimobendan. This can be performed with an echocardiogram or radiographs. If both are available, then an echocardiogram is the preferred initial diagnostic test as it is the more accurate way to assess heart size and can establish a definitive diagnosis of MMVD. If the echocardigram includes Doppler evaluation, the presence and severity of pulmonary hypertension and high left ventricular filing pressures can also be assessed. Stage B2 MMVD can be confirmed if the left atrial size as evaluated by a short-axis left atrial to aortic ratio (LA:Ao) is > = 1.6 and the left ventricular end diastolic diameter normalized to body weight is > = 1.7. Dogs confirmed with Stage B2 MMVD should have pimobendan initiated. (LINK TO THE EPIC, ABCD, MMVD, ACVIM Guidelines)  If an echocardiogram is used to conirm diagnosis thoracic radiographs can be preformed and used as baseline for future comparison in the event that the dog develops signs of congestive heart failure. If an echocardiogram is not available or declined, thoracic radiographs should be performed. If the VHS is > = 11.5 or a VLAS > = 3.0, (LINK to the VHS & VLAS paper) a presumptive diagnosis of Stage B2 MMVD can be made and pimobendan can be recommended. These recommendations are based on the EPIC Study results and the ACVIM  MMVD guidelines . In addition it is also recommended to confirm the dog is normotensive by evaluation of systemic blood pressure. A routine chemistry panel, CBC, urinalysis are a lower priority but can be recommended prior to initiation of any chronic oral medication. Other tests may be indicated in individual patients but overall are lower priority, eg. heartworm antigen testing.

Additional information about radiographs: There is evidence of cardiac enlargement based on a VHS of 11.0 (normal up to 10.5 in dogs, but unique reference ranges are available for some dog breeds, including Cavaliers and should be consulted and used when appropriate (click here for VHS article). The reported normal VHS range for Cavaliers is < 11.1 ). A moderate degree of left atrial enlargment is noted subjectively confirmed by VLAS of 2.8. Normal VLAS for dogs is reported < 2.2. This degree of radiograph cardiomegaly is insufficient to confirm a diagnosis of Stage B2 MMVD. However it is still possible that this dog has Stage B2 MMVD. Client options at this time include an echocardiogram or follow-up thoracic radiographs in 6 to 9 months. An echocardiogram at this time can confirm a diagnosis of Stage B1 versus Stage B2 MMVD. If declined recheck thoracic radiographs in 6 to 9 months can be used to assess for the presence of progressive cardiomegaly (click here for ABCD brochure).

Click here to learn more about the stages of heart disease (ABCD Brochure)