If a murmur or other heart issue is present, over time the heart can enlarge.  The larger the heart gets, the more pressure it puts on the rest of the body.  When this pressure reaches a critical level, the watery component of blood (like the fluid in a blister) begins to weep out of the vessels and accumulates inside or outside the lungs or within the belly.  This is congestive heart failure.  If the lungs develop fluid then it eventually causes a pet to have trouble breathing. 

Definition of terms:
Congestive heart failure:  Fluid accumulation due to heart disease
Pulmonary edema:  Fluid “within” the lungs
Pleural effusion: Fluid “around” the lungs
Pericardial effusion:  Fluid within the heart sac
Ascites or abdominal effusion:  Fluid within the belly or abdomen.

What is an ARRHYTHMIA?

Normal heart beats are produced by an electrical system within the heart muscle.  This system works automatically by using a built in "pacemaker" and ensures that the heart beats at an appropriate rate depending on activity level or the demands placed on the heart.  Problems with this electrical grid can cause an abnormal heart rhythm, termed "Arrhythmia".  Arrhythmias can be either too fast or too slow.  The most common clinical sign for a significant arrhythmia is collapsing or dizziness.  Not all arrhythmias are treated but many are.

Fast arrhythmias (tachyarrhythmia) can cause heart damage and place an animal at risk for sudden death.  They can occur because of an enlarged heart (ie.  Dilated cardiomyopathy, HCM, valve disease).  These arrhythmias usually require treatment.  Sometimes a 24 hour HOLTER monitor is recommended to record heart rhythm overnight in the comfort of your own home for more accurate diagnosis.  Examples of these arrhythmias are:

Ventricular Tachycardia (Vtach)
Atrial Fibrillation (Afib)
Atrial Tachycardia or Flutter
Paroxysmal Supraventricular Tachycardia
Ventricular Premature Contractions (VPC)
Atrial Premature Contractions (APC)

Slow arrhythmias (bradyarrhythmias) can also place a pet at risk for collapsing or passing away suddenly.  Heart enlargement may or may not be present and these arrhythmias can actually cause congestive heart failure.  Sometimes medication or a pacemaker surgery is recommended.  Examples of these arrhythmias include:

AV Block, Atrioventricular Block (1st, 2nd, and 3rd degree)
Sick Sinus Syndrome
Atrial Standstill
Vasovagal Syncope

To learn more about PACEMAKERS click here.

Hypertrophic Cardiomyopathy (HCM), or Hypertrophic Obstructive Cardiomyopathy (HOCM)

HCM is thickening of the heart muscle commonly seen in cats.  Overtime, the thickened muscle can cause heart enlargement.  The larger the heart gets the higher the risk for congestive heart failure (fluid build-up).  Cats, unlike dogs, can develop either fluid within the lungs (pulmonary edema) or outside of the lungs (pleural effusion) with left heart disease.  Pleural effusion requires draining with a needle (thoracocentesis).  Accurately diagnosing heart disease in cats is not an easy evaluation.  Diagnosing HCM could be a matter of 1mm of thickening in the heart wall.  Cats with HCM are at increased risk for developing blood clots (saddle thrombus, stroke, arteriothromboembolism).  Although no medication is proven to completely prevent stroke from happening, we may consider treating this process early on to try to prevent it with aspirin or plavix.  Dogs can develop HCM but is rare.  It is important to rule out high blood pressure, hyperthyroidism, and other forms of heart disease before making the diagnosis of HCM.


Dilated cardiomyopathy is a degenerative disease where the heart begins to lose muscle power and the heart chambers become enlarged.  Dogs and cats with DCM are at risk for developing congestive heart failure and fast heart rhythms.  Sometimes the disease is caused by low amino acid level, Taurine deficiency.  It is very important to identify DCM early when there are no clinical signs of sickness, this time frame is termed "Occult DCM".  There are studies showing that starting medication early in the disease course can delay progression to congestive heart failure.  Dogs live longer, and are sometimes cured, with medication.  We generally expect dogs with the occult form to progress to congestive heart failure within a few years and can pass away suddenly without exhibiting any previous signs.  Once diagnosed with congestive heart failure, or fluid in the lungs or abdomen, prognosis is usually less than a year.  Dogs with DCM, specifically Doberman's and Boxers, are at risk for arrhythmias (Vtach, VPC’s) and a HOLTER monitor is sometimes recommended (24 hour heart rhythm recording in the comfort of you home).  It is uncommon for cats to develop DCM now that Taurine has been supplemented in all cat food, however, DCM can occur in cats and carries a very poor prognosis.  There are several breed predilections for DCM but any breed can develop it.  Below are some of the breeds that are predisposed to this disease:

Doberman Pincher
Great Dane
Irish Wolfhound
Cocker Spaniel

Mitral Valve Regurgitation or prolapse (aka.  Chronic valve disease or endocardiosis)

The mitral valve is a main valve of the heart.  It separates the loading chamber (atrium) from the pumping chamber (ventricle) and prevents blood from moving in the wrong direction.  Overtime, this valve can scar or prolapse (point backwards).  It occurs due to old age and degeneration.  Diseased valves leak and can cause heart enlargement.  The larger the heart gets, the more risk there is for developing congestive heart failure or fluid in the lungs.  Although more common in smaller breed dog disease it can happen in any animal.  It is not a common problem in cats but can occur along with hypertrophic cardiomyopathy.  Medication will likely be recommended to try to slow progression (pimobendan, vetmedin, ace-inhibitor, enalapril, benazepril).  If congestive heart failure if present (fluid in the lungs), this must be immediately treated with diuretics or “water pills” (Lasix, furosemide).  Dogs can also develop pulmonary hypertension, high pressure in the lungs, from the leaky valve.  Some predisposed breeds:

Cavalier King Charles Spaniel

Pericardial effusion

Pericardial effusion is fluid (effusion) build up outside of the heart, within the heart sac (pericardium).  Commonly the fluid is blood and caused by cancer (Hemangiosarcoma, heart based tumor, mesothelioma).  Besides cancer, the fluid can build up from a non-cancerous inflammatory process called idiopathic pericardial effusion, heart failure, or left atrial rupture from valve disease.  Clinical signs of this disease include collapse, lethargy, cough, vomiting, dizziness, and abdominal swelling.  Collapsing can often be intermittent as the pet recovers from the acute bleeding only to have it repeat later.  It is a life-threating emergency and comes on with no warning.  There is no way to realistically screen for this disease before clinical signs appear.  Treatment of pericardial effusion is an emergency and requires puncture of the heart sac by a needle to remove the fluid (pericardiocentesis, or "tap") and allow the heart to fill again.  Idiopathic pericardial effusion can be cured with one tap while some animals require multiple taps.  Left atrial rupture or tear carries a poor long-term prognosis.  Surgery to remove the heart sac is sometimes recommended as a curative option if no cancer is evident.  This disease rarely effects cats. 


Pulmonary hypertension (PH)

Pulmonary hypertension is becoming one of the most insidious cardiac diseases in dogs, and is likely significantly underdiagnosed.  PH is an elevated blood pressure within the arteries of the lungs (pulmonary arteries), NOT high blood pressure in the body (systemic hypertension).  As the heart receives "used" blood, it needs to pump that blood into the lungs via the pulmonary arteries to receive oxygen.  If the pressure within those arteries is high, it creates too much work load on the heart, and leads to low oxygen levels.  Clinical signs of PH are variable and can include collapsing, coughing, trouble breathing, distended abdomen, and low energy.  Dogs with PH can even show no clinical signs.  PH can closely mimic congestive heart failure from a valve problem and requires an expert to diagnose with echocardiogram.  It is not rare for a dog to be treated for heart failure with little response only to be properly diagnosed with pulmonary hypertension at a later date.  Most commonly, PH can either develop on its own (idiopathic disease), secondary to chronic cough (cor pulmonale), or secondary to mitral regurgitation.  We closely monitor dogs with mitral regurgitation for PH.  In most cases we are successful in improving quality and length of life through medical therapy.   Starting therapy at the onset of this disease is the best chance we have to limit the ongoing damage to the heart and vessels.  Sometimes PH can be cured with medicine but is generally palliative.  Prognosis of pulmonary hypertension in dogs is based on the severity, clinical signs present, and response to treatment.  Some dogs are cured while other will have relapses or pass away suddenly.

Why is my dog coughing?

Coughing in dogs is common, especially at older ages.  Our first step in diagnosis the cause of cough is to take chest xrays.  Xrays allow us to visualize the general heart size, blood vessels, and lung tissue itself.  Cats can also cough, see below.  Coughing can seriously impact a pet’s quality of life as well as the owner’s well-being.  Causes for coughing in cats and dogs include:

Congestive heart failure
An enlarged heart pushing on and irritating airways
Pulmonary hypertension
Chronic bronchitis (dogs)
Asthma (cats)
Collapsing trachea or windpipe
Infections, Pneumonia

Why is my cat coughing?

Cats cough mainly from airway disease, most commonly from Feline Asthma.  Feline asthma can be a waxing and waning process and may even have allergic or environmental factors.  As opposed to dogs, cats rarely cough from congestive heart failure but is certainly possible.  It is also possible for cats to deal with 2 problems at once, asthma and heart disease, making it tricky at times to choose the correct medication.  Treatment for asthma may include corticosteroids (prednisolone or Depomedrol).  Corticosteroids can at times actually trigger steroid related congestive heart failure in cats, especially if underlying heart disease is silent.  If a cat has a heart murmur, gallop rhythm or the heart appears enlarged on xrays, and echocardiogram may be recommended before starting steroids to assess the risk for steroid associated heart failure.  Steroids, inhalers (flovent, fluticasone, albuterol) and bronchodilators are often effective treatment for asthma and inflammation. 


Why is my dog or cat collapsing?

Collapsing, or "episodes", has a long list of possible causes.  Often people call these episodes "seizures" but we should not call collapse a seizure unless it truly is one.  Seizures and fainting (syncope) from cardiac disease can look remarkably similar.  Here are some diseases that can cause collapse:

Systemic disease (low red blood cell count, addison's disease, kidney or liver failure, etc)

Cardiac disease (congestive heart failure, pulmonary hypertension, fast arrhythmia, slow arrhythmia)

Vasovagal or neuromediated syncope (fainting from a brief miscommunication within the body resulted in low heart rate and low blood pressure.  This type of fainting can be exacerbated by coughing or disease within a body cavity).

Neurologic disease (seizure, narcolepsy, cataplexy, vestibular ataxia (vertigo), neuromuscular disease)

If no cause of collapsing is found on blood work, physical exam, and heart disease is suspected, a consultation with a Board Certified Veterinary Cardiologist is recommended.  Collapsing can be a life-threatening and impact your pets quality of life.

My pet may have a tumor or enlarged lymphnode in its chest, now what?

We can evaluate the chest for tumor size and sampling if one is suspected on xrays.  Some tumors are too small to see with an echocardiogram (ultrasound of the chest) but often the tumor is identifiable.  A low invasive and generally well tolerated option to try to find out what type of cancer a tumor may be is "FINE NEEDLE ASPIRATE" or FNA.  A small bore needle is inserted into the tumor using ultrasound guidance.  Cells are removed from the tumor and read by a laboratory pathologist.  If results are inconclusive, then a larger needle biopsy can be considered (Tru-cut biopsy).  A fine needle aspirate usually does not require sedation with our service.  Fluid can sometimes form around the lungs due to a lung tumor, this fluid can be removed for comfort, and also submitted for analysis.  A FNA only rules in cancer, it cannot rule it out fully.