Feline asthma is a genetic disease that affects 1 to 5% of cats. Feline asthma is caused by an allergic reaction to inhaled allergens, particles that stimulate a cats immune system. When a cat with feline asthma inhales an allergen their system creates specific antibodies to that allergen. When they recognize the allergen it starts a cascade of events that bring many different types of immune cells to the airways. These immune cells then trigger the production of substances that promote inflammation, a condition that results in irritation, swelling, and reactive constriction of the airways. This can cause the diameter of the airways to decrease and mucus to accumulate. This can cause the inability for air to get into the airways and cause an asthma attack. Signs of such include difficulty breathing, wheezing, rapid breathing, coughing or hacking, open-mouthed breathing, or even vomiting. This can of course vary in intensity depending on the cat. When they have an asthma attack they tend to hunch their bodies close to the ground and extend their necks forward as if to hack up a hairball.
https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-asthma-what-you-need-know https://www.petmd.com/cat/conditions/respiratory/cat-asthma https://trudellanimalhealth.com/blogs/blog/cat-asthma-what-it-is-symptoms-to-look-for-and-how-to-treat-it?srsltid=AfmBOorxNRPA2AkxHwLUM2oavnzNY6UREfbR4tfDuEG1i-lRVRVqL2SB (+ my own experiences will be added when talking about how it will affect the cat respectively)
