Spending quality time with our canine companions can bring such joy to our lives.
We can find countless ways to fill our days with activities that include our dogs – hiking in the woods, swimming in the lake, playing fetch at the park, or strolling on the beach — there are so many opportunities to share with our four-legged friends.
It’s also during these activities that we may begin to notice gradual changes in our dog’s health and behavior as they mature.
Whether we notice an occasional cough, a gradual loss of stamina on walks, or a difference in their breathing pattern at play or even at rest — these can all be signs of early changes in our dog’s heart health.
It’s important to pay close attention to these subtle changes and schedule a veterinary consult as soon as possible to investigate and identify the underlying cause.
Studies have shown that heart disease will affect about 10% of dogs in the United States at some point in their lives. The majority of these dogs are considered seniors (over 7 years of age), but younger adults can also be affected depending on their overall health, breed, and nutritional status.
As with humans, obesity and high blood pressure can be a major contributing factor in the development of heart disease in dogs.
We'll focus on two main types of degenerative changes that can lead to heart disease in older, senior dogs — changes that affect the valves of the heart and those that affect the muscular pump.
Skip to section:
Mitral Valve Disease (MVD)
Mitral valve disease (MVD) is the most common type of heart disease in dogs. It’s estimated that 70–75% of dogs who develop heart disease will have valve disease, and of those, 25–50% will ultimately go on to develop congestive heart failure (CHF).
Some dogs may have very mild symptoms in early adulthood and earlier in the course of the disease. Often, the detection of a heart murmur is the first clue that a dog’s heart function may be changing. With MVD, the murmur generally develops between 6 and 10 years of age.
Left-sided heart murmurs occur due to the turbulent flow of blood back and forth through the mitral valve. If the valve is no longer able to close completely, either due to degeneration or misalignment of the leaves (flaps) of the valve, then blood will back up into the left atrium rather than being pumped out of the heart to the body.
Dogs can also develop tricuspid valve degeneration in the right side of the heart. In this case, blood will regurgitate back through the tricuspid valve and cause enlargement of the right atrium due to the increased volume of blood that is unable to move into the ventricle.
If too much backflow occurs, then fluid will begin to accumulate in the dog’s abdomen (ascites). This accumulation of fluid can put pressure on the diaphragm and chest cavity, causing labored breathing.
Heartworm disease is one of the more common causes of right-sided heart failure in dogs. As adult heartworms reproduce and accumulate in the chambers of the heart, the worms can create a physical obstruction of the tricuspid valve and even clog the pulmonary blood vessels.
Typically, your veterinarian would be able to tell you which side the murmur is on or if it can be heard on both sides.
Heart Murmurs Are Classified as Congenital or Acquired
Congenital murmurs are usually present at birth and, in many cases, will resolve on their own by about 6 months of age.
Acquired murmurs may develop in adult dogs either due to valve disease or heart muscle disease, but with early detection, regular preventive care, regular exercise, and a good plan of nutrition (i.e., prescription diet), many dogs can live close to their normal lifespan without progressing to heart failure.
Breeds Typically Affected by MVD
MVD typically affects small and medium-breed dogs. The most common breeds are Cavalier King Charles Spaniel, Cocker Spaniel, Dachshund, Miniature Schnauzer, Whippet, Miniature Poodle, Shih Tzu, Maltese, Chihuahua, and Pomeranian. It can also affect mixed breeds and larger dogs, but it's less common.
Symptoms of MVD
In addition to a heart murmur, other symptoms of MVD may include coughing, lack of desire or ability to exercise, difficulty breathing (dyspnea), and collapse.
Mitral valve disease can progress to congestive heart failure (CHF), affecting 25-50% of dogs with MVD. The progression rate of mitral valve disease varies, but it generally takes years for clinical signs of congestive heart failure to occur.
See below for more symptoms and information about the progression to congestive heart failure.
Tricuspid Valve Degeneration
Dogs with MVD can also develop tricuspid valve degeneration in the right side of the heart. In this case, blood will regurgitate back through the tricuspid valve and cause enlargement of the right atrium due to the increased volume of blood that is unable to move into the ventricle.
If too much backflow occurs, then fluid will begin to accumulate in the dog’s abdomen (ascites).
This accumulation of fluid can put pressure on their diaphragm and chest cavity, causing labored breathing.
Heartworm disease is actually one of the more common causes of right-sided heart failure in dogs. As adult heartworms reproduce and accumulate in the chambers of the heart, the worms can create a physical obstruction of the tricuspid valve and even clog the pulmonary blood vessels.
Progression to Congestive Heart Failure (CHF)
Congestive heart failure occurs when the heart can no longer adequately pump blood to the body, which then results in blood backing up in the lungs and an accumulation of fluid in the chest and/or abdomen.
The symptoms associated with congestive heart failure include:
- Persistent cough
- Coughing during rest or sleep
- Difficulty breathing
- Weakness
- Loss of stamina or tiring easily
- Avoiding activity
- Increased respiratory rate or excessive panting
- Loss of appetite
- Restlessness
- Swollen belly
- Change in gum color – pale or bluish
- Weight loss
- Muscle loss
- Fainting
- Collapse
- Sudden death
NOTE: If you notice any of these symptoms, especially if your dog has a known heart murmur, contact a veterinarian immediately.
With treatment, dogs can have a great quality of life after developing CHF, and though survival time varies, most live for an additional 12 to 18 months.
Dilated Cardiomyopathy (DCM)
Heart disease in large breed dogs often looks very different from what we see with the smaller breeds of dogs and valve disease.
Large and giant breeds such as Doberman Pinschers and Great Danes are two breeds most susceptible to heart muscle disease, and the onset of symptoms may be a bit more sudden, often in the form of sudden collapse.
The left ventricle has the thickest muscle wall of the heart and is responsible for pumping oxygenated blood from the lungs to the body. If the ventricular wall begins to thin and deteriorate, the pumping action of the heart muscle becomes weaker and less effective in moving blood out of the chamber to the body.
The heart muscle fails to maintain a normal, healthy sinus rhythm because of the flaccid ventricular wall, leading to disruption of the electrical signals that trigger the heart to contract regularly (arrhythmia).
This condition, known as dilated cardiomyopathy (DCM), occurs due to the thinning of the ventricular wall and the resulting dilation of the ventricular chamber.
Ongoing research is happening regarding diet-associated dilated cardiomyopathy. Read more to see what the data is showing about feeding your dog grain-free food.
Symptoms of Heart Muscle Disease
The symptoms of heart disease in dogs can be vague and develop gradually over time, which can make understanding the reason for the onset of symptoms very confusing.
For example, coughing that is a symptom of heart disease can also be a symptom of respiratory disease (such as kennel cough or asthma), aspiration of food or fluid into the airways, parasites (heartworm or lungworm infections), tracheal collapse, bronchitis, allergies to some sort of trigger in the home or the yard, a tumor in the chest that presses on the lungs or the trachea, or irritation secondary to swallowing a foreign object (such as a stick or part of a toy), among other possibilities.
Because there are so many possible causes, it’s important that you pay close attention to the frequency of your dog’s cough, whether or not they are coughing anything up (like food, fluid, blood, or phlegm), and whether you are noticing other concerning symptoms, which could include:
- Loss of appetite/weight loss
- Exercise intolerance – stopping play more quickly than usual, slowing down or lying down during walks
- Difficulty breathing – gasping for breath or wheezing during sudden activity or at rest
- Collapse – with or without loss of consciousness
- Lethargy – decrease in normal activity or energy levels
- Ascites – a bloated appearance to the abdomen that is tense or tight if gentle pressure is applied (this bloated appearance is similar to Gastric Dilatation-Volvulus (GDV); both GDV and Ascites are extreme emergencies)
- Hindlimb weakness
Diagnosing Heart Disease in Dogs
If your veterinarian suspects that your dog may have heart disease, they will often recommend some basic laboratory tests to help them confirm their diagnosis.
They may notice the signs of heart disease at your dog's wellness appointment well before you see the symptoms yourself at home, like a heart murmur.
One of the most common tests for suspected heart disease is a baseline blood work panel to assess your dog’s overall metabolic health, particularly their liver and kidney function.
This information is vital in helping your veterinarian determine which medications will be safest to prescribe for your dog if a diagnosis of heart disease is confirmed.
Dogs predisposed to heart conditions should have, at minimum, yearly diagnostic testing, like X-rays or echocardiograms.
Additional specific tests, such as the NTproBNP marker assay, may be requested, along with a basic blood panel to help determine your dog’s risk of developing heart disease.
NTproBNP is a protein that is released by degenerative or damaged heart muscle cells into the bloodstream and is elevated in dogs that are symptomatic for heart disease.
Imaging tests usually include chest X-rays with vertebral heart scoring, which is based on several measurements of the heart silhouette and will vary with the size and breed of your dog.
An echocardiogram (an ultrasound of the heart) may also be recommended to help identify abnormal blood flow patterns through the heart valves.
An electrocardiogram (EKG) is another helpful diagnostic tool that records the electrical activity of the heart to identify abnormal beats (arrhythmias) that can affect the normal function of the heart muscle.
These tests can typically be performed in your regular veterinarian’s office during an appointment or as an outpatient procedure and usually do not require your dog to be sedated.
Treatment Options for Heart Disease
Once your veterinarian has confirmed that your dog has heart disease, they may recommend starting a regimen of one or more heart medications depending on the specific diagnosis and clinical signs your dog is experiencing.
This treatment regimen may also include the addition of dietary supplements and a prescription diet formulated to provide the necessary protein and nutrients essential to support your dog’s heart health.
Medications
Help with fluid build-up
One of the most common complications that can develop with heart disease is the buildup of fluid in the body — typically in the chest or the abdomen — due to the failure of the heart muscle to pump blood effectively through the vascular system.
If fluid accumulates faster than the kidneys can excrete it, the excess fluid will move into any available space in the body it can find, which is usually in the chest cavity surrounding the lungs (pleural effusion), in the lungs and larger airways (pulmonary edema), or into the abdomen (ascites).
In these cases, your veterinarian may prescribe a diuretic (Lasix, Spironolactone, Hydrochlorothiazide) to help remove this excess fluid from the body by stimulating the kidneys to increase urine output.
The most common side effects of diuretic medications are an increase in thirst and an increase in urination. Some dogs may have accidents indoors, so it's recommended to take your dog out more frequently to avoid this since it can be a source of stress for you and a source of stress for the dog who knows it should not be urinating inside.
Other side effects may include gastrointestinal upset and blood work abnormalities, which is why continued monitoring of electrolytes and kidney function values is very important for dogs on diuretics. We would not recommend limiting access to water.
Improve muscle contractions
For dogs who have weak heart muscle contractility, your veterinarian may recommend starting an ACE inhibitor (Enalapril, Benazapril, Lisinopril).
These medications not only help dilate the blood vessels to support more efficient blood flow through the body, but they can also help the heart muscle pump more effectively to increase cardiac output.
Additionally, another medication called Pimobendan may be prescribed to help with contraction strength and dilation of the blood vessels for improved blood flow through the body.
Help with heart rhythm
If your dog is diagnosed with an irregular heart rhythm, your veterinarian may prescribe anti-arrhythmic medications to help the heart muscle beat more regularly for better blood circulation throughout the body.
Medications such as Digoxin and Diltiazem work to regulate the abnormal rhythms of the upper chambers of the heart (atria). These drugs help regulate the contractions of the heart muscle to move blood from the atria to the ventricles.
Sotalol is another anti-arrhythmic medication that regulates the rhythm of the ventricles, which are the lower chambers of the heart that move blood into the lungs (right ventricle) and out through the aorta to the rest of the body (left ventricle).
There are other anti-arrhythmic medications called beta blockers (Atenolol, Carvedilol), which do help regulate abnormal heart rhythms but also have the ability to cause a decrease in blood pressure to reduce hypertension.
Diet and supplements
Introducing a special diet for your dog with heart disease is often recommended in conjunction with the medications that your veterinarian will prescribe.
Cardiac-friendly diets are typically restricted in salt and phosphorus, which can sometimes make them less palatable for dogs, but salt restriction is necessary to avoid overloading the kidneys as they filter excess fluid out of the body under the direction of diuretic medications.
There are several high-quality prescription cardiac diets from Royal Canin Early Cardiac, Purina ProPlan CardioCare, and Hill's h/d Heart Care that you can discuss with your veterinary team to see which option might be best for your dog.
If your veterinarian recommends supplements in addition to a prescription diet, you can look for options that include taurine, L-carnitine, omega fatty acids, and Coenzyme Q10
If your dog is on prescription medications, make sure to discuss supplements with your veterinarian first before starting.
-
VetriScience Cardio Strength Capsules Heart Supplement for Cats & Dogs
-
VetriScience Vetri Cardio Canine Soft Chews Heart Supplement for Dogs
Coming to terms with a diagnosis of heart disease in your dog can be scary and a bit overwhelming at first, but working closely with your regular veterinarian is vital to ensuring that your dog can continue to live their happiest life with the treatment regimens that are currently available.
