Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Heart disease is common in older dogs. Small breeds most often develop degenerative mitral valve disease, a leaky heart valve usually found as a murmur. Larger breeds are more prone to dilated cardiomyopathy, a weakened heart muscle. Early treatment matters: in dogs with an enlarged heart from valve disease, starting pimobendan before heart failure delays heart failure by more than a year on average. Counting your dog’s sleeping breathing rate at home is one of the best early warning tools.
Signs
- A heart murmur found at a checkup (often the first sign)
- Fast or labored breathing at rest or during sleep
- Coughing, especially at night or after lying down
- Tiring easily on walks
- Restlessness at night, or reluctance to lie down
- Fainting or collapse
- A swollen belly
- Weight loss or poor appetite in later stages
Emergency signs
Go to an emergency vet for labored breathing, blue or gray gums, collapse, or a breathing rate at rest that keeps rising.
Common heart diseases in older dogs
- Mitral valve disease: very common in small breeds such as Cavalier King Charles Spaniels, Chihuahuas, and Dachshunds. Many dogs live years before any signs.
- Dilated cardiomyopathy (DCM): more common in large breeds such as Doberman Pinschers and Great Danes. It can cause heart failure or dangerous heart rhythms.
Staging and treatment
Vets use American College of Veterinary Internal Medicine (ACVIM) stages:
- Stage B1 (murmur, heart not enlarged): monitoring, usually yearly.
- Stage B2 (murmur with an enlarged heart): pimobendan is recommended. In the EPIC trial, it delayed heart failure by about 15 months on average.
- Stage C (heart failure): usually furosemide, pimobendan, and often spironolactone and an ACE inhibitor.
- Stage D (hard-to-control heart failure): adjusted and additional medications.
DCM treatment depends on the stage and rhythm and may include pimobendan and antiarrhythmic drugs.
Home monitoring
- Count sleeping breaths: count breaths for 30 seconds while your dog sleeps, and double it. Many vets advise calling if it’s consistently above about 30–35 breaths per minute.
- Track energy, appetite, and cough.
- Weigh regularly.
Diet and lifestyle
- Avoid salty treats and table scraps.
- Maintain a healthy weight and muscle mass.
- Gentle, regular exercise as your dog tolerates.
- The FDA has investigated a possible link between certain diets (many labeled grain-free and high in peas, lentils, or potatoes) and DCM in dogs. A cause hasn’t been established. Ask your vet about your dog’s food.
What to avoid
- Stopping heart medications without your vet.
- Human heart or blood pressure medications.
- Heavy exercise in heat.
- Supplements in place of prescribed medication. Discuss any supplement (like fish oil or taurine) with your vet.
Frequently asked questions
How long can a dog live with a heart murmur?
Many dogs with a murmur from valve disease live for years without symptoms. Regular monitoring helps time treatment.
Does a cough always mean heart failure?
No. Older small dogs often have airway problems too. X-rays and your vet’s exam help tell the difference.
Can heart disease in dogs be cured?
Most forms can’t be cured, but treatment can extend and improve life. Specialized valve surgery is available at a few centers.
Sources
- Keene BW, et al. ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs. J Vet Intern Med. 2019
- Boswood A, et al. Effect of pimobendan in dogs with preclinical myxomatous mitral valve disease and cardiomegaly: the EPIC study. J Vet Intern Med. 2016
- US FDA: Investigation into potential link between certain diets and canine dilated cardiomyopathy
- Merck Veterinary Manual: Heart disease and heart failure in dogs
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.