Cats may start breathing fast or even panting for a number of reasons, including excessive exertion and overheating. Panting is fairly rare with felines, even under these circumstances. Rapid breathing is more common in elderly, obese, and brachycephalic animals.
Allergies
Allergies to environmental components such as pollen or dust may result in nasal discharge, sneezing, and rapid, shallow breathing. Allergies that affect the respiratory system in cats are frequently accompanied by an allergy induced skin rash as well.
Anemia
Whether caused by loss of blood, the destruction of blood cells or suppressed production of red blood cells, anemia is the reduction in the number of red blood cells that are circulating in the blood. Red blood cells contain the hemoglobin that carries the oxygen throughout the feline body, and when their numbers are reduced the body becomes starved for oxygen, and the cat breathes more rapidly as they attempt to compensate. Toxicity from certain substances, such as acetaminophen, may cause anemia as they cause the red blood cells to become compromised.
Emotional Distress
Stress triggers many of the same physiological responses for felines as it does for humans, including increases in heart rate and respiration. Chronic stress in felines may lead to delayed wound healing, depression, and even upper respiratory infections. Other signs of stress in cats can include clingy behavior, hiding, and overgrooming.
Exertion
Although it is not as common in cats as it is in dogs, vigorous play can occasionally lead to panting. If panting occurs after mild or moderate play, lasts longer than a few minutes, or begins occurring on a more frequent basis, a veterinary professional should evaluate your pet’s health.
Heart Disease
Mild and moderate heart attacks and ongoing heart disease often present with difficulties breathing due to the reduced oxygen circulation. Along with rapid or ragged breathing , the cat may also experience weakness and lethargy, start coughing, and in some cases suffer sudden paralysis of the hind legs.
Heat
Panting can be seen in response to excessive heat, and may be a preliminary sign of heat stroke, particularly if accompanied by restlessness behavior, thick, sticky saliva, or weakness. Brachycephalic cats, obese cats, and the very young and very old are more susceptible to heat stroke than other cats.
Pain
Cats are particularly good at hiding pain, and as such, it may be difficult to spot. One of the signs that your cat may be in pain is an increased rate of breathing, frequently accompanied by agitated behavior, changes in pupil dilation, and an increase in the heart rate. Many cats also purr when they are in distress.
Pleural Effusion
An accumulation of fluid in the pleural sac surrounding the lungs is known as pleural effusion. This condition compresses the lungs and inhibiting the ability to fill with air, causing shortness of breath and rapid breathing, a bluish tinge to the skin and mucous membranes, and lethargy.
Respiratory Disease
Disorders that affect the respiratory system, such as asthma, viral infections, or pneumonia, are frequently characterized by shallow, rapid breathing and panting. Respiratory disease in cats may be accompanied by sniffling, sneezing, and vocal changes.
Sinus Infections
The inflammation of the nasal passages that occurs when your cat develops a sinus infection can cause them to breathe more quickly than is typical. This type of infection would also include the symptoms of sneezing, nasal discharge, bad breath, and sometimes a cough.