Canine heart disease is actually quite common, with 10% of all dogs being affected, and up to 35% of dogs over 13 years of age. Most of these patients have heart disease that develops with age (not a birth defect), and of these, 75% have diseased valve(s), 15% have Dilated Cardiomyopathy (DCM), and 10% have a different issue such as heartworm disease.

Valvular disease is the weakening of a heart valve or valves that allows blood to leak through when the heart contracts. This is very common in older, small and medium breed

dogs like Cavalier King Charles Spaniels, Chihuahuas, Miniature Poodles, Miniature Pinschers, Fox Terriers, Boston Terriers, Miniature Schnauzers, and Cocker Spaniels. It tends to progress gradually, which means we usually have a great opportunity to significantly slow things down and improve these patients’ overall quality and quantity of life.

DCM is a problem with the heart muscle itself, and usually affects middle-aged large breed dogs like Dobermans, Boxers, Great Danes, Newfoundlands, and Cocker Spaniels (who unfortunately make it onto both lists!). These dogs have a stretched out, weak heart muscle that makes pumping blood ineffective, so they unfortunately have a quick onset and rapid progression in most cases.

Testing and treatments are best determined based on the individual dog’s stage:

Stage A: Dogs with currently normal hearts that we know are at high risk. For example, all healthy Cavaliers are considered to have Stage A heart disease because the incidence is so high within their breed.

  • Small breed dogs, especially those with high frequency of developing valvular disease (Cavalier King Charles Spaniels, Dachshunds, Miniature and Toy Poodles) should be examined at least annually to allow for auscultation (listening with a stethoscope) for heart murmur development.

  • No drug or diet treatments are recommended by specialists at this stage.

Stage B: There is now evidence of a structural change within the heart (usually a murmur) but no symptoms.

  • Chest x-rays are needed to establish baseline measurements of the heart and evaluate the severity of heart changes (if present). Chest x-rays should be repeated annually.

  • Blood pressure should be checked annually.

  • An echocardiogram (ultrasound of the heart) may be indicated at this stage based on findings on x-rays or exam.

  • Baseline lab work (at a minimum, measures of red blood cells, protein levels, kidney values, and urinalysis) should be assessed annually.

  • A simple blood test, proBNP, can be useful to determine if the heart muscle is strained and can help us predict how soon heart failure will occur.

  • Monitoring at home—you are our best chance at catching your dog slipping from Stage B into Stage C in time to take action!

    • Resting or sleeping respiratory rate monitored once weekly at home is the best way to catch worsening heart disease. We need to see your dog again as soon as possible if his/her respiratory rate is more than 30 breaths per minute (or more than 15 breaths/30 seconds) for 3 days in a row.

    • We also should see your dog again as soon as possible if you notice reduced activity or coughing.

    • Encourage moderate daily activity, but bring in for recheck evaluation if unable to keep up.

  • Nutrition recommendations:

    • Maintaining a lean body condition generally improves long-term quality of life.

    • Omega-3 fatty acid (EPA and DHA) supplementation may be beneficial. Look for fish oil supplements that do not contain anything additional other than Vitamin E (which is needed to protect the fish oil). Cod liver oil and flaxseed oil are not suitable omega-3 supplements for pets.

    • Mild sodium restriction is recommended. Foods and treats should be less than 100mg sodium per 100Kcal. Avoid baby food, bread, cheeses, lunch/deli meats, most pet treats, rawhides, and bully sticks.

Substage B1: Normal chest x-rays.

  • No medications are indicated.

Substage B2: Abnormal x-rays (usually heart enlargement).

Stage C: This patient has current or previous symptoms of congestive heart failure (CHF), such as reduced activity, increased respiratory rate or effort, unexplained panting, exercise intolerance, or coughing.

  • Chest x-rays, blood pressure measurement, baseline lab work, and echocardiogram are needed.

  • A blood test, proBNP, is also useful at this stage to help differentiate coughing due to heart disease from coughing caused by collapsing trachea (which often occurs along with heart disease in many small breeds).

  • Most dogs do best with “Triple Therapy” at this stage:

    • Vetmedin improves heart chamber filling and produces better heart contractions without making the heart muscle actually work harder. Longer survival times have been proven with this medication.

    • Salix is a diuretic that helps pull off retained fluid around the heart.

      • Free access to water at all times is crucial for pets on diuretics!

    • ACEi medications (benazeprilenalapril) prevent the chronic constriction the blood supply, so the heart can pump into open vessels instead of pumping against narrowed ones.

    • Goals: make the heart work better with less effort, delay progression to stage D, and maintain good quality of life for as long as possible. We need to see your dog again as soon as these treatments are not working!

    • X-rays need to be checked again 10-14 days after starting medications to monitor progress.

  • Dietary changes:

    • Maintain adequate calorie intake to prevent excessive weight (especially muscle) loss that is common at this stage. Avoid low-protein diets unless the patient also has kidney disease.

    • Potassium supplementation is sometimes needed if blood work finds low potassium levels.

    • Omega-3 fatty acid (EPA and DHA) supplementation is recommended. Fish oil supplements should be used, but be sure they do not contain anything additional other than Vitamin E (which is needed to protect the fish oil). Cod liver oil and flaxseed oil are not suitable omega-3 supplements for pets.

    • Sodium restriction is recommended. Foods and treats should be less than 80mg sodium per 100Kcal. Avoid baby food, bread, cheeses, lunch/deli meats, most pet treats, rawhides, and bully sticks.

  • Intensive care may be needed for patients in crisis, but we often avoid this by catching patients at earlier stages and being proactive in managing the heart failure. Critical patients require 24-hour care and may benefit from specialty referral and additional individualized therapy.

  • Home care and monitoring:

    • Appetite and body condition should be followed closely. We need to see your dog as soon as possible if there is a loss of weight or appetite, as it may indicate progression to Stage D.

    • Coughing, reduced activity, or a resting/sleeping respiratory rate of more than 30-35 breaths/minute for 3 days in a row = we need to see your dog again!

    • Resting/sleeping respiratory rate should be monitored daily by Stage C.

    • Exercise should be encouraged as tolerated, but avoid prolonged strenuous activity.

Stage D: This patient is no longer responding well to routine medications and has life-threatening heart failure. Very aggressive care is required and the patient is likely nearing end of life—we are losing the battle at this stage.

  • Referral for cardiologist care is ideal. Higher level testing and specialist evaluation can help identify the best treatment options specific to your pet’s individual case.

  • Medications are usually maximized at this point, and spironolactone (a second diuretic) is usually added on. Other therapies may be helpful based on specialist evaluation, so referral is strongly encouraged.

  • Monitoring at home:

    • Appetite and body condition should still be followed closely. We need to see your dog again very soon if there is loss of appetite or weight or development of a distended belly.

    • Persistent coughing, fluid from the nose, blue or purple gums/tongue or inability to catch his or her breath are indications that your pet needs emergency care.

    • Overall quality of life—if your pet is no longer able to enjoy the activities he or she loves, if your pet cannot sleep comfortably at night, or if your pet is struggling to breath, then humane euthanasia may be indicated to prevent suffering.

Important phone numbers:

Animal Care Clinic: 417-334-7696

Emergency Veterinary Clinic: 417-890-1600

University of Missouri Veterinary Health Center (Cardiology referral): 573-882-7821

Additional resources:

Accurate client handouts on common medications and monitoring resting respiratory rates:

Detailed information on heart disease, testing, treatments, success stories, and a link for a resting respiratory rate monitoring app produced by the maker of Vetmedin:

Tons of accurate articles on various pet health topics, including heart disease:

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