If your dog has been diagnosed with a heart murmur and/or congestive heart failure, there are several considerations for monitoring and possible therapy to help manage this condition successfully. It is important to realize that a heart murmur is not a disease, it is a symptom of heart function and anatomical changes. Many dogs with a heart murmur will never develop heart failure and will lead normal lives. Dogs with asymptomatic heart murmurs do not need any exercise restriction, special diets, medication or treatments. 

At the time of diagnosis of a heart murmur, chest x-rays are recommended to document heart size, evaluate for signs of heart failure and provide a baseline for monitoring progression of heart disease. Other potential tests include an ECG, bloodwork and blood pressure measurement. In addition, an echocardiogram (ultrasound of the heart) may be done to assess the structure and function of the heart. We can help schedule this procedure and a cardiac consultation with a board-certified cardiologist here at our hospital. Good information on heart disease can be found at www.vetcardiologist.com.

Stages of heart disease

There are four stages of heart disease-A, B (B1 and B2), C and D. Stage B signifies a heart murmur is present but there are no clinical signs of disease. The heart may or may not be enlarged. Many dogs will remain in this stage for 2-3 years. Regular monthly monitoring of the resting respiratory rate and chest x-rays every 6-12 months will help with early intervention if heart failure is developing.

Signs of heart failure

Unfortunately, there is a percentage of dogs that will go on to develop heart failure which will impact quality of life, increase the likelihood of sudden death and require medications and lifestyle changes to allow them a comfortable and acceptable life.  Early warning signs of heart disease include coughing, changes in breathing (labored or rapid breathing), shortness of breath, lack of energy, tiring easily, exercise intolerance, fainting (which can be confused with seizures), restlessness at night, change in appetite and sensitivity to heat or cold. 

Treatment of heart failure

Once your dog has signs of heart failure-we are in Stage C. There are three very important drugs that are used to treat this stage.  

• Lasix (furosemide) is a diuretic which helps to remove fluid in the lungs, 
• Vetmedin (pimobendan)-which helps the heart contract and vessels to dilate 
• Enalopril-an ACE-inhibitor that aids in blood flow and prevent hypertension

If patients are responding to the medications, a progress evaluation exam and follow-up labwork will be done within a week to 10 days or sooner if the patient is not doing well. Medications will be adjusted to control clinical signs as well as avoid serious side effects.  As heart failure develops, a referral to a board-certified cardiologist will ensure best possible treatment of the disease and adherence to the drug dosages that work for your dog.

Monitoring Resting Respiratory Rate

Pet owners can best monitor for development of heart failure by assessing changes in the dog’s resting or sleeping respiratory rate that is the earliest sign of congestive heart failure. 

• Establish a baseline. Document how many breaths your dog takes in a minute while sleeping. Normal is <30 breaths/minute. Count the number of times your pet’s chest moves in and out (in and out together counts as one breath) over a period of 1 minute on a clock or watch.
• Monitor weekly once there is evidence of heart enlargement on the chest x-ray.
• Keep a diary or use the RRR app on the app store for iPhone or Android phones or available at www.yourdogsheart.com.

• If the RRR goes above 30 breaths per minute or >20% increase in 6 hours, your dog should be evaluated.