If your dog has a persistent cough, they could have an underlying heart condition. Coughing is a common heart disease sign in dogs, because fluid can accumulate in the lungs when the heart doesn’t pump appropriately. Our Groves Veterinary Clinic team wants to provide information about what cardiac conditions commonly affect dogs, in case your four-legged friend is affected.
Heartworms in dogs
Heartworms are transmitted by mosquitoes. When a mosquito takes a blood meal from an infected dog, they ingest baby heartworms (i.e., microfilariae) that grow to an infective stage inside the mosquito and can be transmitted to another dog when the mosquito feeds. Dogs are natural heartworm hosts, which means the parasites can grow to adulthood, breed, and produce offspring while parasitizing the dog. Other important information about heartworms includes:
- Signs — In the early stages, most dogs don’t exhibit any signs. They typically present first with a mild, persistent cough, followed by other signs that include lethargy, exercise intolerance, decreased appetite, and weight loss.
- Caval syndrome — A high worm load can cause a blood flow blockage inside the heart, leading to a condition called caval syndrome, whose signs include pale gums, labored breathing, and sudden collapse. Caval syndrome is a veterinary emergency, and requires immediate surgical removal of the worms to prevent death.
- Diagnosis — Diagnosis is typically made through a blood test that detects antigens produced by the adult female heartworm. The American Heartworm Society recommends annual testing in dogs to screen for these parasites. Other testing, such as chest X-rays and an echocardiogram, may also be recommended to determine the extent of the damage to your dog’s heart.
- Treatment — A dog who is diagnosed with heartworms must be activity restricted, because exercise can exacerbate the parasite damage. Our veterinary team will first stabilize your dog’s condition to help minimize side effects, and then start treatment, which involves administering medications over several months to kill the heartworms at every life stage. We will closely monitor your dog’s condition throughout treatment to ensure the inflammatory response caused by the heartworm die-off doesn’t cause a problem.
- Prevention — Heartworm disease can easily be prevented by providing year-round heartworm prevention medication.
Mitral valve disease in dogs
Mitral valve disease (MVD) is the most common heart disease cause in dogs. The upper heart chambers (i.e., atria) and the lower chambers (i.e., ventricles) each have a one-way valve to prevent blood from flowing backward. The mitral valve goes between the left atrium and left ventricle, and degenerative mitral valve changes cause the structure to thicken, which prevents a tight seal and allows blood to leak from the ventricle into the atrium during each heartbeat. To compensate for the inefficient, leaky valve, the heart must pump harder to adequately perfuse the body, which over time, causes the heart to enlarge and eventually leads to congestive heart failure (CHF). Other important MVD information includes:
- Dogs at risk — MVD is most common in dogs older than 5 years of age, and small-breed dogs, such as toy poodles, cocker spaniels, Chihuahuas, and Yorkshire terriers, are at higher risk.
- Signs — The earliest MVD sign is usually a heart murmur, which can be detected at your dog’s annual wellness examination. As the condition progresses, signs include coughing, difficulty breathing, exercise intolerance, fainting, and weight loss.
- Diagnosis — Common diagnostics include X-rays, blood tests for cardiac biomarkers, an electrocardiogram (ECG), an echocardiogram, and possibly a Holter monitor (i.e., a wearable device that monitors your dog’s heart rhythm for 24 hours).
- Treatment — Treatment depends on the severity of your dog’s condition. Potential treatments include:
- Diet change — Your dog may be switched to a low sodium diet to help prevent fluid retention.
- Diuretics — These medications stimulate the kidneys to remove excess fluid.
- Vasodilators — These medications dilate the arteries and veins throughout the body to facilitate blood flow.
- Cardiac drugs — Our veterinary team may prescribe medications to help improve your dog’s heart muscle function.
- Prevention — MVD can’t be prevented, but routine wellness checks can detect the condition in the early stages when the disease is easier to manage.
Dilated cardiomyopathy in dogs
Dilated cardiomyopathy (DCM) is characterized by heart enlargement and decreased heart contractility. Heart muscle degeneration causes muscle wall thinning, and the blood pressure inside the heart stretches the thin wall, resulting in an enlarged heart. The heart wall changes reduce the heart’s ability to effectively pump blood throughout the body, eventually leading to CHF. Other important DCM information includes:
- Dogs at risk — DCM most commonly affects large-breed dogs such as boxers, Doberman pinschers, Great Danes, and Saint Bernards.
- Signs — Signs include coughing, difficulty breathing, exercise intolerance, fainting, and weight loss.
- Diagnosis — Diagnostics include chest X-rays, blood tests for cardiac biomarkers, an ECG, an echocardiogram, and a Holter monitor.
- Treatment — DCM has been linked to certain diets, and your dog’s diet may need changing. Diuretics, vasodilators, and cardiac medications may also be prescribed to manage the condition.
- Prevention —Avoid feeding your dog grain-free, exotic, or boutique diets, as they have been linked to DCM development in some cases. Non-diet-related DCM can’t be prevented, but regular wellness checks can catch the condition in the early stages when management is easier.
Heart conditions commonly cause coughing in dogs, and catching these conditions early is important to improve your dog’s prognosis. If you would like to schedule a wellness exam for your dog, contact our Groves Veterinary Clinic, so we can ensure their heart is beating normally.