What is heart disease?
Heart disease refers to any abnormality of the structure or function of the heart. The heart can be divided into five functional components:
- The heart muscle pumps blood around the body
- The heart valves keep blood flowing in the right direction
- The heart’s electrical system coordinates heart muscle contraction and keeps the heartbeat regular
- The major vessels carry blood into and out of the heart (pulmonary vein and aorta)
- The pericardium, a protective sac, surrounds and protects the heart
Heart disease can affect any or all of these parts.
What are the signs of heart disease in dogs?
Most dogs display no clinical signs until heart disease is advanced. Often, it may be detected earlier if your veterinarian hears a heart murmur during a physical examination.
The most common signs of heart disease in dogs are:
- Coughing and difficulty breathing
- Exercise intolerance (tiring quickly during walks or play)
- Weakness or collapse
- Weight loss
- Lethargy
- Swelling or bloating of the abdomen (belly)
- Stunted growth in puppies
Is a heart murmur always a sign of heart disease?
Most heart murmurs in dogs are a sign of heart disease. A heart murmur is an extra sound caused by abnormal or turbulent blood flow in the heart or blood vessels leaving the heart. In dogs, heart murmurs are most commonly caused by structural problems in the heart (pathologic murmur). Less commonly, they may occur secondary to other changes like anemia (innocent murmurs).
What types of heart disease occur in dogs?
One way to categorize heart disease is to split it into congenital disease, where there is an abnormality at birth, and acquired disease, which develops later in a dog’s life.
Examples of congenital heart disease include:
- Valve malformations (pulmonary valve stenosis, subaortic stenosis)
- Abnormal connection between the aorta and the pulmonary artery (patent ductus arteriosus)
- Defects in the heart wall that divides the right and left sides of the heart (e.g., ventricular septal defect)
Examples of acquired heart disease include:
- Chronic degenerative valvular disease (i.e., mitral valve disease)
- Dilated cardiomyopathy
- Arrhythmogenic cardiomyopathy
- Pericardial disease
Are some dog breeds at higher risk of heart disease?
Heart disease can occur in any dog, but certain breeds may have an increased risk of certain heart conditions, including:
- Chronic degenerative valvular disease: Small Breed Dogs Especially: Cavalier King Charles Spaniel, Dachshund, Miniature Poodle, Yorkshire Terrier, Papillon, Chihuahua
- Dilated cardiomyopathy: Doberman Pinscher, Boxer, Great Dane, Irish Wolfhound, English Cocker Spaniel, Portuguese Water Dog, Newfoundland, Standard Schnauzer
- Patent ductus arteriosus (PDA): Bichon Frise, Chihuahua, Cocker Spaniel, Collie, English Springe Spaniel, German Shepherd, Keeshond, Maltese, Pomeranian, Poodle, Shetland Sheepdog, Welsh Corgi, Yorkshire Terrier
- Pulmonic stenosis: Basset Hound, Beagle, Boxer, Chihuahua, Chow, Cocker Spaniel, English Bulldog, Labrador, Mastiff, Miniature Schnauzer, Newfoundland, Samoyed, West Highland White Terrier
- Subaortic stenosis: Boxer, Bull Terrier, German Shepherd, German Shorthaired Pointer, Golden Retriever, Great Dane, Newfoundland, Rottweiler, Samoyed
How is heart disease diagnosed?
Depending on the murmur and the degree of clinical signs, your veterinarian may recommend further testing to determine the cause. Additional testing commonly includes:
- Chest X-rays (radiographs)
- An electrocardiogram (ECG), which records the heart’s electrical activity
- An echocardiogram (cardiac ultrasound)
If your veterinarian suspects that the heart murmur is secondary to another disease, more extensive tests may be recommended.
Can heart disease be detected early?
Several genetic tests are available to identify dogs that may be more likely to develop certain types of heart disease. However, these tests are not useful for every dog. Talk to your veterinarian about whether genetic testing would be beneficial for your dog.
If genetic testing shows your dog is at higher risk, your veterinarian may recommend regular blood screens, X-rays, ECGs, Holter monitoring (prolonged ECG), and echocardiography. These tests can help detect changes in your dog’s heart before they feel sick. The most important step in finding heart disease early is recognizing the signs and seeking veterinary care as soon as possible so treatment can begin right away.
