Dog Heart Conditions
Understanding your dog's heart condition is the first step toward providing them with the best possible care. Learn about the cardiac conditions we commonly diagnose and treat.
Common Heart Diseases in Dogs
These are the most frequently diagnosed cardiac conditions in our canine patients.
Chronic Valvular Degeneration (CVD)
A degenerative, progressive heart disease affecting many dogs that can lead to congestive heart failure.
Chronic Valvular Degeneration (CVD) is a degenerative, progressive heart disease that affects many dogs. The valvular changes can lead to a volume-overload of the heart and increase pressures within the heart. The heart responds to this increase in pressure by dilating.
Patients with moderate-severely dilated cardiac chambers can be at risk for developing spontaneous congestive heart failure (fluid build-up in the lungs or abdomen) and/or developing cardiac arrhythmias.
The echocardiogram (cardiac ultrasound) allows us to evaluate your pet's risk for congestive heart failure. Depending on this risk, medical therapy may be recommended. Unfortunately there is no known therapy to prevent progression of the valvular degeneration itself. However, certain hemodynamic factors can be altered via medical therapy that may reduce the risk for congestive heart failure.
Typically patients with CVD progress slowly. Rapid progression is possible, but rare. Typically CVD is treated medically but there are more progressive interventional options emerging.
Dilated Cardiomyopathy (DCM)
A disease of the heart muscle causing pump function failure, predisposing patients to heart failure and arrhythmias.
Dilated Cardiomyopathy (DCM) is a disease of the heart muscle that causes the pump function of the heart to fail. This leads to increased pressures within the heart and predisposes the patient to congestive heart failure as well as increasing the risk for cardiac arrhythmias and sudden death.
Medical therapy is indicated to support the pump function of the heart as well as mediate some of the hormonal changes that occur at this stage of heart disease. Unfortunately medical therapy will not offer a cure for this disease but can improve patients' quality and quantity of life.
Nutritional factors can cause and/or exacerbate DCM and should be considered carefully. We work closely with pet parents to ensure optimal dietary management alongside medical therapy.
Pulmonary Hypertension
High blood pressure in the pulmonary circulation that can be primary or secondary to an underlying cause.
Pulmonary hypertension (PH) is high blood pressure in the pulmonary circulation. PH can be primary in nature or secondary to an underlying cause. It is difficult to definitively diagnose the underlying causes of pulmonary hypertension.
Disease processes that can lead to pulmonary hypertension include: • Severe mitral regurgitation • Chronic inflammatory airway disease • Pulmonary thromboembolic disease (blood clots developing and/or travelling to the lungs) • Chronically elevated left atrial pressures (chronic left-sided heart disease) • Chronic high-altitude living • Pulmonary neoplasia (cancer in the lungs) • Pneumonia • Heartworm disease
Prognosis for patients with pulmonary hypertension is variable depending on the underlying cause and the patient's response to treatment. Medical therapy is warranted in patients with moderate-severe pulmonary hypertension. Unfortunately, pulmonary hypertension is not curable but medical therapy can often improve patients' quality and quantity of life.
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)
An inherited disease common in Boxer dogs causing degeneration of heart muscle connections and dangerous arrhythmias.
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is common in Boxer dogs. ARVC is an inherited disease that causes degeneration of the connections between the myocardial (heart muscle) cells. This leads to myocardial cell death and replacement of these cells with fat and fibrous (scar) tissue.
Most commonly in dogs with ARVC, the abnormal heart tissue causes ventricular arrhythmias (early and fast heart beats coming from the bottom of the heart). The frequency and severity of ventricular arrhythmias varies among patients.
A Holter monitor (a 72-hour ECG that your pet can wear) is often recommended in patients with ARVC to help characterize your pet's arrhythmias. Clinical signs can include syncope (passing out) or pre-syncope (weakness or wobbliness due to poor blood flow to the brain). Some patients with ARVC never have significant clinical signs, despite severe arrhythmias.
Medical therapy is often indicated in these patients and can help alleviate the clinical signs as well as decrease the risk for sudden death.
Rhythm Disturbances in Dogs
Cardiac arrhythmias require specialized diagnosis and management.
Ventricular Arrhythmias
Ventricular arrhythmias can occur for a myriad of reasons. Primary cardiomyopathy and infiltrative disease are common causes and suspicion for this can be identified on an echocardiogram.
The underlying cause of a ventricular arrhythmia is often not determined. Intra-cardiac causes such as focal areas of the heart muscle due to fibrosis (scarring), ischemia (poor blood flow) or inflammation are not definitively identified on an echocardiogram.
Extra-cardiac causes are considered and can be due to any inflammation released into the systemic circulation. The most common extra-cardiac cause is an abnormality of the spleen (both benign as well as malignant processes).
Ventricular arrhythmias increase risk for sudden death.
Sinus Node Disease
Primary sinus node disease typically occurs secondary to fibrosis (scarring) of the sinus node. This causes the resting heart rate to be slower than normal. This also leads to inability to increase heart rate and support blood pressure when needed (as occurs under anesthesia).
Unfortunately there is no cure or medical therapy to improve sinus node disease. The only appropriate therapy for significant sinus node disease is a pacemaker.
A Holter monitor (72-hour rhythm assessment) is often helpful identifying a patient's need for pacemaker if indicated.
AV Block
AV block is an electrical malfunction of the heart's conduction system. Normal electrical activity starts in the atrium and is conducted down to the ventricle by way of the AV node.
AV blockade can occur secondary to a structural problem of the conduction system itself or can be secondary to pathology elsewhere in the body. If conduction blockade causes the heart rate to be too slow to maintain appropriate blood flow it can lead to exercise intolerance and/or fainting.
There is a risk for sudden death in patients with third degree AV block (the most severe stage). In some patients AV Block can lead to pacemaker implantation.
Congenital Heart Disease in Dogs
These conditions are present from birth and often detected in puppies during routine examinations.
Subaortic Stenosis (SAS)
Subaortic stenosis (SAS) is caused by a congenital malformation of the left ventricular outflow tract below the aortic valve. The diameter of the valve is narrowed causing the left ventricle to work harder in order to meet the body's needs for blood flow.
This causes the left ventricle to increase in thickness and can lead to clinical complications. Depending on the severity of the stenosis as well as complicating factors, patients with subaortic stenosis are at risk for: • Ventricular arrhythmias • Syncope (passing out due to poor blood flow) • Left-sided congestive heart failure • Sudden death
Evaluation by echocardiogram is important to assess this risk.
Pulmonic Stenosis (PS)
Pulmonic stenosis (PS) is caused by a congenital malformation of the pulmonic valve. The diameter of the valve is narrowed causing the right ventricle to work harder in order to meet the body's needs for blood flow.
This causes the right ventricle to increase in thickness and can lead to clinical complications. Many patients with pulmonic stenosis live a normal life span. However, depending on the severity of the stenosis as well as complicating factors, patients with pulmonic stenosis are at risk for: • Ventricular arrhythmias • Syncope (passing out due to poor blood flow) • Right-sided congestive heart failure • Sudden death
Evaluation by echocardiogram is important to assess this risk. In patients with moderate-severe pulmonic stenosis an interventional procedure may be helpful.
Patent Ductus Arteriosus (PDA)
Patent Ductus Arteriosus (PDA) is a persistent communication between the pulmonary artery and the aorta. In utero, the ductus is used to bypass the lungs because the fetus does not need to oxygenate its own blood. At birth, this ductus should close so that blood flows through the heart and lungs efficiently and effectively.
In patients with a PDA (a ductus that does not close) blood is allowed to re-visit the lungs and the left side of the heart without going to the body. This causes a volume and pressure overload of the left side of the heart. Left untreated, most of these patients will develop left-sided congestive heart failure within the first year of life.
Treatment requires surgical intervention. The two options for closure of a PDA include: • Catheter-based technique: Minimally invasive, usually obtains full PDA closure. Involves a small incision in the groin and using a long catheter to place a device inside the PDA. Risk for complication is relatively low. • Thoracotomy technique: Requires surgical opening of the chest and dissection of the PDA. Usually leaves trivial flow across the PDA and the risk is higher for death during the procedure.
Unfortunately, medical therapy alone is not effective at preventing congestive heart failure in these patients. If the PDA is small, closure may not be necessary. Echocardiogram helps determine the individual complexities of patients with a PDA.
Ventricular Septal Defect (VSD)
A Ventricular septal defect (VSD) is a hole caused by a malformation of the wall that separates the left and right ventricles. When there is a hole between the ventricles, blood is allowed to re-visit the lungs and the left side of the heart without going to the body.
This causes a volume and pressure overload of the left side of the heart. Left untreated, these patients can be at risk for left-sided congestive heart failure.
Evaluation by echocardiogram is important to assess this risk. Medical therapy may be indicated if there is a risk for congestive heart failure.
Concerned About Your Dog's Heart?
Early detection and proper management can significantly improve your dog's quality of life. Schedule a consultation with Dr. Ginieczki today.