How does a vet diagnose heart disease

Copy Link
Stethoscope laying on EKG papers
Stethoscope Laying On EKG Papers

If you have been noticing signs of heart disease or failure in your dog or cat, such as coughing, difficulty breathing, or passing out, it is imperative you take it for your vet to get a proper diagnosis before it's too late. Diagnosing heart disease and/or heart failure in the dog and cat requires a combination of several different testing methods.

Physical Examination

Accurately diagnosing any disease or condition always begins with a thorough physical examination. A complete physical examination may uncover a symptom that suggests the possibility that your dog or cat is suffering from heart diseases, such as a heart murmur (also sometimes seen in cats), an abnormal rhythm known as an arrhythmia, evidence of fluid in the lungs or in the abdomen, or other signs seen with heart problems.

Your veterinarian will also ask about your pet's history. Specifically, you may be asked whether your pet coughs, tires easily, sleeps more than normal, breathes heavily and similar types of questions.

black and white short fur cat lying on bed
black and white short fur cat lying on bed

Radiography (X-Rays)

One of the most important diagnostic tests that can be done to diagnose heart disease in both the dog and the cat is a chest radiograph (x-ray).

  • A chest x-ray can show abnormalities in the size and shape of the heart and large blood vessels that may indicate heart disease.
  • A chest x-ray may also show evidence of fluid accumulation in the lungs, leading to a diagnosis of heart failure.

Radiographs of the abdomen may show evidence of fluid accumulation in the abdominal cavity, known as ascites. This is a finding that can be seen in heart failure also.

brown tabby cat eating beside wall
brown tabby cat eating beside wall


An echocardiogram is an ultrasonic examination of the heart. This diagnostic test allows visualization of how the individual structures of the heart are functioning.

An echocardiogram can show disturbances in the natural flow of blood through the heart and indicate whether the valves of the heart are functioning normally. It can also be used to measure the dimensions of various parts of the heart and can aid in determining whether the muscle of the heart is contracting effectively.


An electrocardiogram (EKG or ECG) measures the electrical activity of the heart. An electrocardiogram is the only diagnostic test that can be used to detect and diagnose heart arrhythmias (abnormal heartbeats or rhythms). Arrhythmias can occur with many different types of heart disease.

orange tabby kitten
orange tabby kitten

NT-proBNP Blood Testing

The Nt-proBNP test is a blood test which is done by some veterinarians to help determine whether signs are due to heart disease or respiratory disease. Some veterinarians believe it may also have some use as a means of predicting the prognosis of heart disease.

Other Diagnostic Testing

Your veterinarian will likely want to monitor the blood pressure of your dog or cat if he has been diagnosed with heart disease. There is an increased risk of hypertension (high blood pressure) for these animals.

Additionally, other testing may be necessary if an underlying cause of heart disease is suspected.

orange and white kitten
orange and white kitten
  • Thyroid testing may be necessary if hyperthyroidism is suspected as a cause, particularly in cats.
  • Heartworm testing may be recommended if heartworm infection is possible.
  • Decreased taurine levels can cause some forms of heart disease and may be recommended.
  • A culture and sensitivity test may be in order if a bacterial infection is suspected. A culture and sensitivity test is used to identify the infecting bacteria and the antibiotic which is most likely to control the infection.

In most cases, a combination of history, physical examination findings, and diagnostic laboratory testing* are necessary to accurately diagnose heart disease and/or heart failure in the dog or cat.

* = Radiographs, echocardiogram, electrocardiogram and/or the NT-proBNP test.