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Heart Attack in Dogs

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Myocardial Infarction in Dogs


Much like in humans, a heart attack (or myocardial infarction) in dogs occurs when blood flow to a portion of the myocardium (the heart's muscular wall) is blocked, causing the premature death of a portion of the myocardium. Generally, this is due to the formation of a blood clot (or thrombus) within the blood vessels or heart.


Heart attacks are rare in both dogs and cats.


Symptoms and Types


  • Weakness
  • Lethargy
  • Vomiting
  • Difficult breathing
  • Obesity
  • Low-grade fever
  • Lameness
  • Increased heart rate
  • Collapse
  • Sudden death




  • Atherosclerosis and coronary artery disease
  • Nephrotic syndrome
  • Vasculitis (inflammation of blood vessels)
  • Hypothyroidism
  • Bacterial infection
  • Tumor(s)




You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms. The veterinarian will then conduct a complete physical examination, paying close attention to the dog's cardiovascular system. Various laboratory tests -- such as complete blood count (CBC), blood culture biochemistry profile, and urinalysis -- will be used to help identify the underlying cause of the heart attack.


Blood testing may reveal an increased number of white blood cells (leukocytes), often seen during infections. The biochemistry profile, meanwhile, may show abnormally high levels of liver enzymes or abnormally low levels of T3 and T4 hormones (especially seen in dogs with hypothyroidism). Echocardiography is another excellent tool used to evaluate of cardiac abnormalities.




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