What is congestive heart failure (CHF) and what does it mean for my pet?

Heart failure is a scary sounding term. You never want to hear it applied to your beloved cat or dog. It fills everyone with anxiety and makes it sound as though this could be the end of the road for their pet.

However, this couldn’t be further from the case. I dislike the term for this reason. In this article, I want to explain more about this concerning condition—and why there is still lots of hope for treatment.

As a veterinary cardiologist, I’ve treated thousands of dogs with congestive heart failure and have seen most of them go on to live good-quality lives despite the diagnosis.

❓ So what is CHF?

Congestive heart failure is what happens when the heart becomes too weak or inefficient. The heart is simply a pump, and if it isn’t pumping enough blood, things go wrong. This pumping failure can happen on the left side, the right side, or both sides.

Important: The heart is still working and pumping when heart failure occurs—just not actively enough. This is very different from the heart stopping completely (as in some arrhythmias), which is far more dramatic and life-threatening.

In veterinary cardiology, we use the term CHF to describe a specific situation: when the body starts retaining too much salt—and as a consequence—water.

While exercise intolerance often precedes this in humans, we rarely see this clearly in dogs and cats, for many complex reasons.

As a result of water retention, serious problems can occur:

• 🌬️ Left-sided heart failure usually causes fluid to build up in the lungs, leading to faster breathing.

• 🫃 Right-sided heart failure often causes fluid to accumulate in the abdomen or chest, making the abdomen swell.

🔍 Typical symptoms

CHF can present with a range of symptoms:

• 🐾 Rapid, difficult breathing (especially during rest or sleep)

• 😮‍💨 Coughing

• 🍽️ Reduced appetite or energy

• 🚶 Lower exercise tolerance

• ⚡ Fainting or collapse

• 🫄 Enlarged or bloated abdomen

👉 Rapid breathing is the most reliable sign—this is why we recommend monitoring the Sleeping Respiratory Rate (SRR) closely at home. Here's how to do it.

⚠️ What causes CHF?

CHF is the end result of many different heart issues:

• Dogs: Most commonly due to degenerative mitral valve disease, with rarer causes including dilated cardiomyopathy, congenital defects, and others.

• Cats: Most often caused by hypertrophic cardiomyopathy and related conditions.

🩻 Diagnostics

Your vet will sometimes suspect congestive heart failure based on the presenting symptoms and examination findings.

But they may need to do additional tests such as:

• X-rays - actually one of the best quick tests to check the lungs for fluid accumulation.

• An echocardiogram - see my article on what’s involved.

• Blood tests - for cardiac biomarkers and screening for other conditions.

💊 Treatment

The key message: CHF is often treatable, especially in the earlier stages.

It is possible to reverse this accumulation of excess fluid in the lungs and other parts of the body using drugs - called diuretics.

First line treatment

Typically vets use a drug called frusemide, but sometimes a more potent one called torasemide is also used.

While stabilising your pet the vet may need to give them oxygen therapy, which is a big help when the lungs are half full of fluid to make sure the blood still gets the supplies it needs.

They may even use a pulse oximeter, the red light probe that can measure oxygen saturation in the blood stream. However – these are quite unreliable on most animals due to the hair and skin pigmentation on most extremities.

Additional medications

In addition your vet may use other medications, such as:

• Pimobendan – a medication that helps the heart beat more powerfully

• ACE inhibitors – drugs that reduce the feedback system that drives the retention of fluid

• Spironolactone - a potassium sparing diuretic that also reduces cardiac remodelling.

Successful treatment is not guaranteed – it depends on many factors especially how severely ill your pet’s heart is, but also how early the problem is detected.

Advanced Therapies

In later stages of CHF, all sorts of therapies are being tried, such as:

• Additional diuretic classes, like thiazide diuretics
• Newer drugs, like SGLT2 inhibitors
• Potassium supplementation
• Injectable diuretics
• Interventions - eg TEER and atrial septal puncture
• Surgery - eg Mitral valve repair

🏠 Monitoring at Home: What You Can Do

Once your pet is under treatment there is a huge amount you can do.

📈 Track the Sleeping Respiratory Rate (SRR)

Not only is the SRR useful for detecting CHF in the first place, it can be super useful to monitor progress and treatment effectiveness.

Over time, diuretics tend to become less and less effective at controlling the CHF, but usually higher doses can work wonders so getting the dose right is essential

👀 Watch for subtle changes in behavior

Lots of other things can change as heart failure symptoms ebb and flow. People with the condition experience things like fatigue, weakness, lack of energy, dizziness, confusion, fluctuating appetites and difficulty sleeping.

Our pets can’t really describe any of these feelings to us but you may get an idea that things aren’t feeling right from watching their behaviour closely.

📋 Keep a medication log or use an app (e.g. Cardalis)

There can be a lot of medications to keep track of with congestive heart failure. Keeping a log of drugs, doses and symptoms can be useful as memory can play tricks on all of us, particularly important when there is more than one person involved in the pet’s care.

Often changes might be made multiple times to a diuretic dose, so having an idea of what is working best can be hard to keep track of without a written record.

Use a notebook or an app like Cardalis to track:

• Medications

• Dosages

• Changes

• SRR and other symptoms

📉 Prognosis & Quality of Life

Its really a challenging topic to address the prognosis of congestive heart failure. It can’t be denied it is a real concern and can affect your pet’s quality and length of life severely sometimes. However – some dogs sometimes go on for a long time with minimal problems.

Prognosis depends heavily on the underlying cause.

Dogs with degenerative valve disease typically have much better outcomes than those with dilated cardiomyopathy

With degenerative valvular disease, various studies suggest a mean survival time ranging between 6 to 14 months. Although this information needs to be considered as very approximate as there is a huge potential range of outcomes and some pets do live for multiple years on treatment.

The mean survival time is just the average - and no pet is average. The range is much more relevant, and studies often report things like 3-800 day ranges - for example one looking at advanced heart failure cases only (1).

What matters most: ensuring comfort and stability for as long as possible through medication and careful monitoring.

💧 Getting the diuretic dose right

It’s very important to ensure the diuretic dose is increased appropriately as the disease progresses.

Studies have shown that dogs with advanced congestive heart failure live much longer when given much higher doses of diuretic than those that aren’t.

Some under-treatment may be due to caution or missed opportunities. Its hard to know.

So its always worth discussing with your vet or cardiologist about whether you should try a higher dose of diuretic if symptoms aren’t improving.

🚨 When to Worry — Emergency Signs

If you see these signs, you should get emergency advice about your pet:

• A sleeping respiratory rate > 40 - that isn’t settling

• 😮‍💨 Gasping, or open-mouth breathing, or a very marked chest movement with each breath

• 😴 Severe lethargy, weakness, or collapse

🤝 Final Thoughts

CHF can feel overwhelming—but it is often manageable with the right care plan.

• Maintain contact with your vet for advice and guidance.
• Consider getting a veterinary cardiologist’s input as well.
• Monitor treatment effectiveness with SRR and logs
• Don’t hesitate to increase diuretics (under guidance)
• If SRR > 40, act fast—contact your vet

Check out my video on the same topic if you want a more in depth explanation:

References

(1) Beaumier A, Rush JE, Yang VK, Freeman LM. Clinical findings and survival time in dogs with advanced heart failure. J Vet Intern Med. 2018 May;32(3):944-950.

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