DOGS AND CATS · OWNER EDUCATION
Heart Disease
Heart conditions can involve valves, heart muscle, electrical rhythm or fluid-related complications; dog and cat warning signs are not identical.
THE SHORT VERSION
What matters for your animal?
Start with the warning signs and when-to-contact sections if your animal is unwell. The same outward change can have several causes, so this guide helps you prepare questions rather than identify a diagnosis on your own.
What is this condition?
Heart disease describes several different conditions rather than one diagnosis. Dogs commonly develop certain valve disorders, while cats may develop heart-muscle disease; electrical rhythm problems can occur in either species.
Heart disease includes different structural and functional problems, and an abnormal sound does not define the stage by itself. Testing distinguishes the type of disease and whether complications are present. Some patients need monitoring before medication, while others need active treatment. Changes in comfortable resting breathing can be important, so ask for an individual home-monitoring plan and clear emergency instructions.
Heart disease describes a problem with the heart, but it does not always mean that the animal is in heart failure. The examination and tests help identify the affected structure, the stage of disease, and whether circulation or breathing is compromised. Different diseases can produce similar outward signs, and some animals have substantial disease before an owner notices a change. Treatment and monitoring therefore depend on the diagnosed problem, not simply on the presence of a murmur or the animal's age.
Which species does this guide cover?
The species listed above are the focus of this guide, rather than a complete list of every animal that can develop this condition. Causes, testing and treatment may differ between species and individual patients.
Why can it happen?
- Valve degeneration, heart-muscle disease, congenital abnormalities or rhythm disorders.
- High blood pressure, endocrine disease or other conditions can affect heart function.
- Age, breed and individual history change risk.
What might an owner notice?
- Coughing, reduced exercise tolerance, fainting or abnormal breathing.
- Cats may show subtle lethargy, rapid breathing or sudden weakness without a cough.
- Severe cases can involve fluid accumulation, collapse or painful blood clots.
Breathing effort is often more important than the sound an animal makes. Watch for increased work of the chest or abdomen, an unusual posture, inability to settle, or a change from that animal's normal pattern at rest. A quiet animal may still be struggling. If breathing is difficult, repeated handling can add stress and worsen the situation. Contact the appropriate veterinary service promptly and follow transport instructions rather than spending time trying to identify the cause at home.
How is the problem investigated?
Physical examination, chest radiographs, electrocardiogram and blood pressure when indicated. Echocardiography to evaluate heart structure, valves and function. Laboratory testing and specialist consultation depending on the clinical question.
Imaging provides information about location, size, shape, and structural changes. Radiographs and ultrasound often answer different questions, so one does not simply replace the other. Images may reveal a complication or guide sampling without establishing the exact microscopic cause. Some procedures require sedation or anesthesia to obtain accurate images safely. Ask what the proposed study is expected to clarify and how its possible results would influence treatment, further testing, or referral.
Blood-cell testing and a chemistry profile provide complementary information. Cell counts can help assess anemia, inflammation, and platelets; chemistry measurements help assess organs and internal balance. Results are interpreted against the species, examination, hydration, medication history, and previous values. A value just outside the reference interval is not automatically the cause of illness. Trends can be more useful than one result, particularly when the aim is to monitor a chronic problem or check that treatment remains safe.
What might treatment involve?
Medication and activity guidance selected for the specific heart condition. Emergency oxygen or hospital care when breathing is compromised. Monitoring of symptoms, heart structure, rhythm and other organs when recommended.
This is an overview, not a prescription or a recommendation for a specific individual animal.
What can owners do at home?
Track resting breathing, appetite, energy and prescribed medication use. Know the clinic’s emergency instructions for respiratory distress or collapse. Keep follow-up imaging and laboratory appointments.
Avoid actions that could make care less safe.
- Do not force exercise or give human heart medications.
- Do not delay care for open-mouth breathing, blue gums or sudden limb weakness.
- Do not give human medications, leftover prescriptions or supplements without veterinary approval.
- Follow the written medication plan. If a side effect is suspected, contact the veterinary team immediately and follow the drug-specific stop instructions; suspected NSAID side effects require stopping that NSAID and calling the veterinarian.
- Do not delay assessment if symptoms are worsening, the animal stops eating or an emergency sign appears.
What can the longer-term outlook involve?
Heart-disease prognosis depends on the exact diagnosis, severity, presence of congestive failure or rhythm problems, and the animal’s response to treatment.
A recheck is not simply a repeat of the first appointment. It assesses whether the original problem is improving, whether complications are appearing, and whether the treatment remains appropriate. The useful measures may include comfort, function, intake, body weight, examination findings, or selected tests. Ask which changes are expected before the visit and which should trigger an earlier call. Improvement in one sign does not always mean that every part of the disease has resolved.
Can risk be reduced?
Keep recommended wellness and heartworm prevention appointments. Discuss murmurs, breed-associated concerns and abnormal breathing promptly.
When should you arrange care?
- Call for new cough, reduced stamina, fainting or changes in resting breathing.
Seek urgent veterinary advice if you notice:
DO NOT DELAY URGENT CARE- Difficulty breathing, open-mouth breathing in a cat, blue or pale gums, collapse or sudden severe painful weakness of a limb.
What information helps the care team?
Write down when changes started, what makes them better or worse, actual food and water intake, and all medicines and supplements. Short videos and a medication-label photo can help describe changes that may not appear during the appointment.
How should you understand the tests?
Ask what each proposed test is intended to answer. Some tests identify a cause; others assess severity, organ function or treatment safety. Results are interpreted with the examination and history. A normal result does not exclude every problem, and an abnormal result does not always explain every sign.
Questions to ask before leaving
- What is confirmed, and which other explanations are still being considered?
- What changes should we expect with the proposed plan, and when should we reassess if they do not occur?
- Which observations should I record, and which changes mean I should call sooner?
- What medicine or home-care problems should I report, and what are the instructions for a missed dose or suspected side effect?
- When is the recheck, what will it assess, and whom should I contact after hours?
A care plan may be adjusted as results or the response become clearer. Keep the written instructions and tell the team if cost, handling or administration difficulty makes the plan hard to follow.
Sources behind this guide
American Animal Hospital Association veterinary guidelinesVeterinary, university or animal-health guidance ↗Cornell University: hypertrophic cardiomyopathy in catsVeterinary, university or animal-health guidance ↗Content last reviewed: October 3, 2026. Review status: veterinary-informed; independent veterinarian review not yet completed.