When dogs are overheated, after exercise or on a hot day, they pant — a natural mechanism for cooling off and part of their heat dissipation process known as thermoregulation. Panting also helps dogs oxygenate their blood. While chronic heavy panting can indicate a health problem, generally, it's perfectly normal for dogs to pant. On the other hand, if your cat is panting, characterized by rapid, open-mouthed breathing, it's a red flag.
Why is My Cat Panting?
Let's explore the reasons a cat may pant, when it's normal, and how to know when it's symptomatic of an underlying health problem that requires veterinary attention.
When panting is normal
Cats can overexert themselves during a strenuous play session with their housemates — especially energetic, young kittens — or a case of the "zoomies" (a sudden burst of frenetic energy), then experience a brief episode of panting before returning to normal breathing. Stressful events such as vet visits, car rides, or changes in your cat's environment can also bring on a bout of panting. If it's over quickly and does not continually reoccur unprompted, panting is most likely not a problem.
Cats who go outdoors in hot weather may pant if they become overheated. The best place for any pet on a hot day is inside an air-conditioned home. If your cat is still panting when he's cooled down inside, it could be a sign that he's not OK. Heatstroke and hyperthermia can occur on a hot day when your cat is not able to find a shady, well-ventilated spot to cool off appropriately, or does not have access to fresh, cool water.
When should I take my cat to the vet?
When panting is continuous and persistent or sudden onset with no let-up, seek veterinary care as soon as possible. Your cat is in obvious distress and her panting is potentially a sign of one of several feline medical issues, including congestive heart failure, feline asthma, pleural effusion, upper respiratory infection, pain from an underlying medical condition or an injury, and hyperthermia.
Panting and congestive heart failure
Hypertrophic cardiomyopathy, or HCM, is by far the most prevalent form of heart disease in cats causing congestive heart failure, which occurs when the cat's heart cannot pump enough blood to the body and fluid backs up into the lungs. In feline HCM, the walls and ventricles of the heart become thickened or hypertrophied. The condition is more prevalent in certain breeds, including Maine Coon, Ragdoll, British shorthair, sphynx, chartreux and Persian cat, which suggests that genetics plays a role. Surprisingly, many cats with HCM do not appear to be ill or are asymptomatic while others display classic symptoms of congestive heart failure, such as labored or rapid, open-mouthed breathing, otherwise known as panting, as a result of fluid accumulating in or around the lungs.
Congestive heart failure can also be caused by thyroid disease, birth defects, high blood pressure, and other conditions. Because cats mask illness very well, and do not cough like people who have congestive heart failure do, in addition to panting and general open-mouth breathing, watch your cat for signs of lethargy or sluggishness, breathing difficulties — sometimes after only a short walk across the room — and in more severe cases, leg paralysis due to blood clots which are prone to occur in the hind limbs.
Panting and feline asthma
During an asthma attack, your cat will have a dry, hacking cough that sounds like gagging or retching. He may breathe through his mouth, or pant, wheeze, and extend his neck as he hunches his shoulders. Due to a lack of oxygen, his lips and tongue may turn blue. Triggered by stress, allergens such as smoke, household chemicals, and even dust in kitty litter, obesity, parasites, or heart conditions, feline asthma affects cats of all ages worldwide.
Panting alerts you to heatstroke, a state of hyperthermia
A panting cat in a hot, humid, inadequately ventilated environment is a cry for help, an alert for you to take action. Panting only increases as heatstroke progresses. It is a life-threatening condition that requires urgent treatment before it causes damage to your cat's internal organs including brain damage.
Heatstroke, or heat stress, is a state of hyperthermia distinguished by an elevated core body temperature above the normal range when heat generation exceeds the body's ability to lose heat. If your cat has been outside in the heat even for a short time and shows signs of distress such as panting, bring her inside. If she has been left outside in the heat for longer, say if you were away from home for awhile, and panting heavily, don't delay. Heatstroke can quickly turn fatal. Seek veterinary care immediately.
Unfortunately, many people don't realize how extremely sensitive cats and dogs are to heat. Despite ubiquitous warnings in the media, every summer, thousands of pets suffer heatstroke or a worse fate when left alone in parked cars baking under the sun. With inadequate ventilation and no way to escape, panting alone cannot sufficiently cool them down. On a 78-degree day, the temperature inside a parked car can morph into 100 degrees in just minutes, and on a 90-degree day, in less than 10 minutes, the interior temperature becomes a scorching 109 degrees.
Panting in cats — an early warning sign
The bottom line is: if you catch your cat panting with no apparent reason, for example; exertion, stress, excitement, or an extremely brief exposure to outdoor heat, consult with your vet as soon as possible. Cats have myriad potential medical issues throughout every stage of life, and in all cases, early diagnosis of a condition where panting is a warning sign is critical for successful treatment and recovery.