Dr Phil Brain
What questions do you get asked most commonly by referring veterinarians regarding cardiology cases?
The two main questions I get asked by referring vets regarding cardiology cases are:
- When should I start cardiac medications such as Pimobendan?
- When should I start diuretic medications and other medications for Congestive Heart Failure?
So, when should you start Pimobendan?
Ideally commencing Pimobendan would be based on echocardiographic parameters – so it is ideal to refer if necessary.
Less ideally, if no echocardiography – and you are presented with a small dog, > 6yo, loud murmur (>3/6), cardiomegaly radiographically based on VHS (> 10.5) or newer parameter VLAS (>3.0) it is reasonable to start pimobendan
What are the benefits of Pimobendan?
The EPIC study showed that Pimobendan can create a 15 month delay in Congestive Heart Failure. 60% more time in stage B2 (pre Congestive Heart Failure). 10% more life without Congestive Heart Failure.
What about Congestive Heart Failure and starting diuretic medication – when should you start?
It’s easier to start by answering when you shouldn’t start it. That’s when you have a coughing dog with a murmur and no evidence of pulmonary oedema. Ideally only start frusemide as a trial if increased SRR and radiographic evidence of pulmonary oedema AND/OR echocardiographic parameters supportive of increased atrial pressure.
Almost always a dog in CHF is a small dog, with a loud murmur, no sinus arrhythmia and left atrial enlargement- an exception to the rule is ruptured chordae tendinae when there may not be left atrial enlargement seen. A Frusemide trial can be done and document radiographic pulmonary oedema resolving and SRR decreasing to normal.
Do not use cough as indication to start or as a tool for monitoring.
But, some veterinarians tell me that a frusemide trial has resolved or improved a cough, doesn’t that mean that frusemide treatment is needed?
It’s more likely due to anti-tussive and bronchodilatory effects of drug. Using a cough only as a reference will result in too much frusemide than is necessary.