Disease Guide

Myocardial Infarction in Dogs & Cats: Symptoms, ECG & Care Guide [2025]

Myocardial infarction is uncommon in dogs and cats, but may occur secondary to thrombosis or aortic aneurysm; signs include acute collapse and cardiac arrhythmia.

Last updated: 2026/01/05
Pethealthmap Editorial Team
Sources: ACVIM, AAHA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek emergency care immediately

  • Severe difficulty breathing or significant labored breathing
  • Sudden collapse or prolonged loss of consciousness
  • Gums or lips visibly turning purple or pale

Schedule a clinic visit soon (within 24–72 hours)

  • Noticeably low energy or slow to respond
  • Persistent loss of appetite or near-complete refusal to eat
  • Repeated vomiting or prolonged inability to keep food down

01What symptoms signal a problem?

Myocardial infarction in dogs and cats often presents as non-specific but acute physical changes; common external signs include decreased alertness and activity, appetite changes, and abnormal breathing.

  • Noticeably low energy and slow responsiveness
  • Weakness and a marked drop in activity level
  • Significant decrease in appetite or near-complete refusal to eat
  • Repeated vomiting or persistent inability to eat
  • Abnormal body temperature or fever, possibly with secondary infection
  • Difficulty breathing, rapid breathing, or obvious respiratory distress

Seek emergency care immediately if you notice the following symptoms:

  • ⚠️ Difficulty breathing or severe respiratory distress
  • ⚠️ Sudden collapse or prolonged loss of consciousness
  • ⚠️ Gums or lips visibly turning purple or pale

02How can you assess the situation at home? Key observations and when to go to emergency

Recording key information at home helps the vet quickly understand the course of illness and symptom changes.

  • Note the time symptoms first appeared and any subsequent changes
  • Measure and record body temperature and trends daily
  • Track the number of vomiting episodes, what was vomited, and bowel movements
  • Monitor breathing rate, and watch for labored breathing or open-mouth breathing
  • Record food intake, water consumption, and changes in activity level
  • Capture video or photos so the vet can compare changes over time
  • If abnormalities are observed, arrange a clinic visit or emergency appointment promptly

03How will the vet make a diagnosis? Common tests and examinations

At the clinic, the vet will combine a physical examination with blood tests and imaging to identify the cause and assess the severity of the condition.

Physical examination

assessment of heart and lung sounds, pulse, and circulatory status

Blood and biochemistry panel

evaluating overall metabolism and organ function

Electrocardiogram (ECG)

assessing arrhythmias and conduction abnormalities

Cardiac ultrasound (echocardiogram)

evaluating cardiac contractility and structural changes

Advanced imaging (CT/MRI)

used for unknown causes or complex cases

Urinalysis

helps rule out renal and metabolic issues

Recommended to visit a specialist hospital equipped with cardiac ultrasound

04How is treatment managed after diagnosis? Medications, diet, and care guide

Treatment and follow-up depend on the severity of the condition; the acute phase may require hospitalization for monitoring and supportive care, followed by long-term follow-up based on test results.

  • Hospitalization may be required during the acute phase to monitor cardiac and circulatory status
  • Medication or supportive therapy will be arranged based on test results
  • Diet adjustment and restriction of vigorous activity to reduce cardiac workload
  • Regular follow-up appointments to track cardiac function and blood biochemistry
  • Imaging or echocardiogram monitoring to track disease progression and treatment response
  • Referral to a cardiology specialist for more comprehensive long-term management if needed

05What should you prepare before the vet visit? Key information to help the vet identify the cause

1
Note the time symptoms first appeared and record any subsequent changes
2
List recent food intake, vomiting episodes, bowel movements, and water consumption
3
Bring a list of all current medications and supplements
4
Prepare short video clips or photos showing abnormal breathing or activity
5
Note whether the pet has been exposed to toxins or had any recent injuries
6
Call ahead before the visit to schedule an appointment or notify the clinic of an emergency

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.

Frequently Asked Questions (FAQ)