Feline lower airway disease (FLAD), or feline asthma, is a common clinical syndrome with a variety of presenting characteristics. FLAD is thought to typically develop as a hypersensitivity response to inhaled allergens, although the specific allergen is rarely found.
FLAD is a disease characterized by airway smooth muscle thickening, excessive mucus production and airway inflammation. These characteristics result in clinical signs of coughing and wheezing (sometimes respiratory distress). Due to the thickening of the airways, it becomes difficult for inhaled air to be exhaled and a very typical expiratory pattern is observed.  The prevalence of FLAD is unknown, as the most common clinical sign is cough, and owners frequently misinterpret this as a hairball.  
Indoor pollutants, including perfumes and dusty kitty litters have also been implicated, and some cats have seasonal signs.

Clinical signs of affected cats include cough, wheeze and respiratory distress. Cats are usually between 1-10 years old when they are first affected.
Older cats, while they will continue to have asthma throughout their lives should not develop asthma for the first time as geriatrics. Any time asthma is suspected in an old cat, a complete evaluation should be performed, as an underlying condition is much more likely present.

Diagnosis of FLAD requires chest radiographs, but a full workup (including bloodwork) should be performed to exclude other cause of cough or respiratory distress (i.e heart disease, parasites, neoplasia).

Treatment of FLAD is with anti-inflammatory steroids. Steroids work to calm the immune response and inflammation in the lungs. Steroids can be administered via injection, orally, or inhaled via a special inhaler designed for cats. Pending the individual cat’s medical history along with the ability of the owner to administer various routes of medication, the best treatment modality will vary from cat to cat. Response to initial therapy occurs within the first 24 hours of treatment. 
As in people, asthma is a lifelong condition in cats and depending on the severity of the asthma, routine chest radiographs for monitoring will need to be done. Frequency and duration of treatment will also vary from cat to cat pending severity of disease.