My Cat Is Breathing Heavy and Seems Lethargic: 9 Reasons Why

Heavy breathing is not commonly seen in cats. Couple that with a lack of energy and it’s pretty easy to worry. These behaviors, especially in combination, are usually a sign there is something wrong. You might need to book a veterinary appointment to get your cat the treatment it needs.

In this article, you can find all the reasons for heavy breathing and lethargy in cats. As you’ll learn, heavy breathing is normal in some cases. But it can also point to several medical conditions. Whenever my cat is breathing heavy and seems lethargic, I assess the situation to figure out which of these two scenarios applies. And with the help of this article, you can do the same!

Keep reading to discover all the common potential causes and what other symptoms to look out for. I also help you decide whether or not you need to bring your cat to the vet – but if in doubt, always give them a call just in case.

What is Considered Heavy Breathing in Cats?

Firstly, I want to touch on what heavy breathing is in cats. Generally, you shouldn’t be able to see or hear your cat’s breathing unless you pay very close attention. If you can, it is a sign that your cat’s struggling to breathe.

You can also measure your cat’s respiration rate. Simply set a timer for 30 seconds and count how many times your cat’s stomach rises and falls. Multiply this number by two and you have their respiration rate. When at rest, this should be around 20 to 30 breaths per minute. If your cat is breathing faster than this, they’re breathing heavily.

However, heavy breathing doesn’t necessarily need to be fast. Breathing can also be considered heavy if any of the following apply:

• Crouching with neck stretched to breathe
• Noisy breathing and rattling breaths
• Breathing with an open mouth

When is Heavy Breathing Normal in Cats?

There are a few non-concerning situations that cause heavy breathing in cats: during and after exercise and if you have a flat-faced breed. If you notice your cat breathing hard and either of these applies, try not to worry. As long as the breathing returns to normal and there are no other symptoms, your cat is likely fine.

1. During & After Exercise

When cats exercise, their bodies use up a lot more oxygen than at rest. This oxygen is used to power the muscles, tissues, and organs. In turn, the muscles can move more quickly and dynamically, and the heart can pump blood more efficiently to where it is needed.

Your cat’s breathing rate increases during exercise to help get more oxygen into the body to where it is needed. This heavy breathing will continue after the exercise has finished, too. The body is still low on oxygen as it has been working so hard. Therefore, heavy breathing continues until all the oxygen in the muscles, tissues, and organs has been replenished.

This is a normal and actually extremely useful reason for heavy breathing. It works on the basis of a natural feedback loop and helps your cat’s recovery after strenuous exercise. Until your cat has recovered, tiredness is commonly seen as well which is often confused with lethargy.

2. Flat-Faced Breeds

Flat-faced breeds such as Persian cats also tend to struggle more with breathing efficiently. This is because their airways are quite literally squashed inwards to give them that characteristic short nose. It is more difficult for air to fit through these narrowed airways, so many flat-faced cats breathe heavily to try and get more oxygen into the lungs.

The term used for this is called brachycephalic airway syndrome. There is technically no condition that is causing their breathing difficulties, it is just caused by their genetics. Therefore, how much cats are affected by the syndrome varies from case to case.

If your flat-faced cat has only minor breathing difficulties, avoiding strenuous exercise and maintaining a healthy weight (consider buying cat weighing scales if you don’t own them already) will be enough to manage symptoms. However, if your cat is constantly struggling to breathe you must see your vet. They might be able to offer anti-inflammatory medication or, in severe cases, surgery.

Why is My Cat Lethargic and Breathing Heavy?

In all other cases, heavy breathing is a cause for concern. This is often the case when your cat is also showing lethargic behavior – lethargy is a common symptom of many medication conditions. Therefore, whenever my cat is breathing heavy and seems lethargic, I take my cat to the vet. You should do the same, especially if any of the following apply:

• Your cat’s heavy breathing does not subside quickly
• There is no obvious “normal” cause for heavy breathing
• There is gagging, coughing, and other signs of struggle
• Your cat’s gums are blue or purple
• Your cat regularly breaths through the mouth
• There are any other behavioral changes or symptoms

Many issues cause these symptoms, some of which are listed below. Read through these to learn more about what could be wrong with your cat prior to your veterinary appointment.

1. Feline Asthma

One of the most common causes of heavy breathing in cats is feline asthma. Like the human condition, this is caused by a narrowing of the airways. This narrowing usually occurs in response to a trigger, such as an allergen or cold air. The allergen causes inflammation of the airways, which leads to swelling and constriction.

It is more difficult for air to pass through these constricted passages. Therefore, cats breathe heavily to try and get more oxygen into the lungs. This heavy breathing can happen at any time – a cat breathing heavily while resting, after exercise, or anywhere in between could be asthmatic. As long as the trigger is present, their asthmatic symptoms can start to show.

There are a few signs to note alongside heavy breathing and lethargy. You might see your cat coughing but no hairball comes up. More often than not, it’ll be coughing with its tongue stuck out. Wheezing is another notable and characteristic symptom to look out for, which worsens considerably during an asthma attack.

2. Heartworm Disease

Cats can get all kinds of parasitic infections, and most cats will deal with at least one case of fleas and worms in their lifetime. However, there is one type of parasitic worm you want to hope your cat doesn’t catch: heartworm. Heartworm is a serious, potentially fatal disease known to cause heavy breathing and lethargy in cats.

The disease is caused by long parasitic worms that live inside your cat’s heart, hence the name heartworm. As the worms grow and multiply, they then being to travel from the heart to the lungs through the associated blood vessels. These worms cause real damage to the heart and lungs, which causes serve breathing difficulties and heavy breathing.

Lethargy is also a common symptom. The presence of heartworms in the blood vessels prevents the normal passage of blood. This means tissues and organs are deprived of the oxygen they need. In fact, heartworm disease can cause cats to become so exhausted that you might see your cat’s third eyelid showing and lethargic behavior to the extreme.

3. Congestive Heart Failure

Congestive heart failure is when your cat’s heart is unable to pump blood around the body efficiently. This often leads to fluid accumulating in places that it shouldn’t, such as the lungs. The fluid on the lungs prevents them from inflating and deflating properly, so the breathing rate increases to try and get more oxygen into the body. Your cat’s breath will be rapid, short, and shallow.

At the same time, your cat’s dysfunctional heart starts pumping harder and harder to try and get blood to where it is needed. Over time, this causes the heart muscle to grow bigger, so the chambers inside the heart get smaller. With a reduced capacity, less oxygen is therefore delivered to where it is needed, causing the lungs to work even harder!

Therefore, although a condition of the heart, it causes respiratory symptoms in the later stages of the disease. In fact, breathing difficulties are the most common symptoms of this condition. If you see your cat breathing hard and fast, it could have congenital heart disease.

4. Upper Respiratory Infections

Heavy breathing and lethargy are common symptoms of most upper respiratory infections. Common examples in cats include feline herpesvirus (FHV-1), feline calicivirus (FCV), and Bordetella Bronchiseptica. All affect the structures of the upper airways such as the nose, nasal passages, throat, and larynx, rather than the lungs themselves.

The presence of a pathogen – be that viruses or bacteria – in the airways causes inflammation and swelling. In turn, this causes the airways to become more narrow. Some also lead to the overproduction of mucus, which further blocks the passage of air into the lungs.

As a result, cats breathe heavily and deeply to get more oxygen into the body. The presence of mucus also usually means your cat sounds congested when breathing. At the same time, the current lack of oxygen can make cats sleepy and lethargic. Other symptoms are common to that of the human cold and include things like coughing, sneezing, a runny nose, and ocular discharge.

5. Anemia

Anemia is a condition in which cats have a reduced oxygen-carrying capacity. In other words, they cannot carry enough oxygen in their blood. Oxygen is usually carried by hemoglobin found in the red blood cells. Therefore, anemia is either down to a reduced number of red blood cells, or a reduction in hemoglobin on these cells.

As all your cat’s tissues and organs need oxygen to function, the lack of oxygen being delivered makes your cat extremely lethargic. A cat breathing heavily through the nose is another common symptom of this condition. The body knows it is not getting enough oxygen and so increases its breathing rate to try and compensate.

The other thing to look out for is pale gums. Pale pink or white gums are the most easily observed clinical symptom of anemia. This is a sign that the gums are not receiving enough oxygen and indicates that the same is likely true for other tissues within your cat’s body.

6. Feline Infectious Peritonitis

Feline infectious peritonitis (FIP) is a viral disease in cats. It is caused by certain strains of the feline coronavirus that infect the GI tract. These are known as feline enteric coronavirus strains. More often than not, this causes minor asymptomatic infection cats can easily fight off. However, in around 10% of cases, mutations cause the virus to become more harmful. This new virus causes FIP.

Because of this unique cause, FIP is one of the least understood of all cat diseases. It is unclear what causes the virus to mutate, and why this only happens in some cats. Diagnosis is also challenging as there are no tests that can distinguish between the initial and the mutated form of the virus.

The early symptoms of the condition are also vague and don’t help much with diagnosis. You might notice your cat is lethargic and reluctant to eat, but that’s about all! However, after several weeks, fluid starts to accumulate in various cavities, including the lungs. This leads to breathing difficulties and heavy breathing.

7. Heatstroke

Finally, heatstroke could be the reason your cat is breathing heavy and seems lethargic. All cats have an optimal body temperature at which their bodies function most effectively. They have various mechanisms in place to help stay within this optimal range. For example, curling up in a ball when too cold and grooming more frequently when too hot.

Unfortunately, these mechanisms don’t always work. In extreme temperatures, your cat can get too hot and the body temperature will continue to increase more and more. At this point, it is common to see your cat breathing heavily with an open mouth. They’re trying to cool themselves down through panting, much like we are used to seeing with dogs.

Cats that are suffering from heatstroke are also lethargic. They’re so hot and exhausted, they don’t want to move at all! You need to help your cat cool down quickly, as the situation is only going to get worse. Their rising body temperature can cause their breathing rate and heart rate to continue to quicken, and the situation can become fatal.

Should I Call the Vet if My Cat Is Breathing Heavy & Seems Lethargic?

As you can see, there are many reasons why you might see your cat struggling to breathe. Several of these are serious medical conditions! So, yes – you should call your vet as soon as possible. Breathing is essential to survival and you should never ignore any type of breathing problem.

In some cases, your vet might find nothing serious wrong, which is great! Examples include an upper respiratory infection which can usually be treated easily with a case of antibiotics and a little rest and recovery. If you do have a less serious problem on your hands, you’ll likely notice your cat coughing, sneezing, and with runny eyes.

However, some quite serious conditions can severely impact your cat’s ability to breathe. If there is a more serious problem you might notice pale gums, panting, open mouth breathing, and very loud breathing. When coupled with lethargic behavior, these clinical signs are even more worrying. These symptoms indicate that your cat needs more urgent medical attention.

Are you unsure whether or not your cat has a breathing issue, or how quickly they need to be seen by a vet? If so, use the list below to help you figure out the best course of action.

If your cat is breathing heavily and any of the following apply, call your vet as soon as possible and book an emergency appointment:

• Your cat is breathing with an open mouth repeatedly
• Your cat is showing signs of struggle, such as noisy and rapid breathing
• Your cat has pale gums (either pale pink or white)
• Your cat suddenly collapsed due to a lack of oxygen
• Your cat already has an underlying medication condition
• Your cat is elderly or a very young kitten

If the above symptoms or situations do not apply, it is still advisable to speak to your vet. However, you don’t need an emergency appointment – just a simple check-up will suffice.

MY FINAL THOUGHTS

Whenever my cat is heavy breathing and seems lethargic, I automatically panic. Seeing your cat struggle to breathe can be extremely worrying and might point to a severe condition. However, it is vital that your remain as calm as possible.

If mild symptoms, book your cat in for a regular appointment. However, if your cat is showing severe breathing difficulties, you need to schedule an urgent veterinary check-up. Never wait for things to improve, as a quicker response from you will improve the chances of survival.

And if your cat does stop breathing completely, start performing CPR and call your vet urgently. Act quickly and get help when it is needed and there is no reason your cat won’t survive.