Asthma and Bronchitis in Cats
OVERVIEW
“Upper respiratory tract” (also known as the “upper airways”) includes the nose, nasal passages, throat (pharynx, larynx), and windpipe (trachea)
“Lower respiratory tract” (also known as the “lower airways”) includes the bronchi, bronchioles, and alveoli (the terminal portion of the airways, in which oxygen and carbon dioxide are exchanged)
Bronchitis is thought to result in air flow reduction due to airway physical changes, while asthma is thought to reduce air flow due to constriction or spasms that narrow the airways but they appear similar outwardly.
Asthma—sudden (acute) or long-term (chronic) inflammation of the lower airways, associated with increased responsiveness of the airways to various stimuli, airway narrowing, and presence of eosinophils, lymphocytes, and mast cells within the airways; “eosinophils” are a type of white blood cell—they are involved in allergic responses by the body and are active in fighting larvae of parasites; “lymphocytes” are a type of white blood cell that are formed in lymphatic tissues throughout the body—they are involved in the immune process; “mast cells” are immune-system cells that frequently are located near blood vessels—they contain histamine and are involved in allergy and inflammation
Long-term (chronic) bronchitis—inflammation in the lower airways (bronchi and bronchioles) with no specific cause; chronic daily cough of greater than 2 months' duration. The terms “feline bronchitis” and “feline bronchopulmonary disease” are used to describe the clinical syndrome in cats of sudden (acute) or long-term (chronic) coughing and/or wheezing (squeaking or whistling sounds) due to lower airway inflammation
Signalment/Description of Pet
Species
Cats
Breed Predilections
Siamese appear to be more likely to develop asthma or bronchitis than other breeds
Mean Age and Range
Any age; more common between 2 and 8 years of age
Predominant Sex
One study indicated that females are more likely to develop asthma or bronchitis than males
Signs/Observed Changes in the Pet
Coughing, sneezing, labored breathing or wheezing
Signs typically are episodic (off and on) and can be sudden (acute) or long-term (chronic, > 5 days)
Severely affected cats have open-mouth breathing, rapid breathing (known as “tachypnea”), and bluish discoloration of moist tissues (known as “mucous membranes”) of the body, caused by inadequate oxygen levels in the red blood cells (known as “cyanosis”)
Increased sensitivity to feeling the windpipe (trachea) is common
Listening to the chest with a stethoscope (known as “chest auscultation”) may reveal short, rough snapping sounds (known as “crackles”) and/or squeaking or whistling sounds (wheezes), or may be normal
Labored breathing, with an increase in expiratory effort; “abdominal push” refers to the act of expiration or exhalation (breathing out) with the help of the muscles of the abdomen
Causes
Triggers or causes of airway inflammation are unknown
Risk Factors
Cigarette smoke, dusty cat litter, hair sprays, and air fresheners may make the disease worse
Use of potassium bromide (treatment for seizures) has been implicated causing signs of asthma or bronchitis in some cats
Treatment
Health Care
Remove cat from the inciting environment
Pet should be hospitalized for a sudden (acute) respiratory distress
Oxygen therapy and sedatives in a sudden (acute) crisis, characterized by breathing distress
Minimize handling during a crisis, in order to lessen stress and oxygen needs of the cat
Activity
Usually self-limited by the cat
Diet
Calorie restriction for obese cats
Medications
Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive
Emergency Treatment
Combine the use of oxygen and a medication that enlarges the bronchi and bronchioles in the lungs, administered by injection (medication known as a “parenteral bronchodilator”); terbutaline is a β-2 agonist that is used as a bronchodilator; administered by injection
A sedative (such as butorphanol, buprenorphine, or acepromazine) can aid in decreasing anxiety
A short-acting steroid, administered by injection, also may be required, such as dexamethasone sodium phosphate or prednisolone sodium succinate (Solu-Delta-Cortef®), administered by injection, also can be used
Long-Term Management
Steroids
Decrease inflammation
Steroid (e.g., prednisolone) administered by mouth is preferred over administration by injection, because doses and duration can be monitored more closely; administer steroids as directed by your pet's veterinarian
Some cats only need steroids on a seasonal basis
Longer-acting injectable steroids (such as Vetalog® or Depomedrol®) will be reserved only for situations in which owners are unable to administer medication inhaled or by mouth on a routine basis
Inhaled steroids—require a form-fitting face mask, spacer, and metered-dose inhaler; veterinary brands include AeroKat™ or NebulAir™; the most commonly used inhaled steroid in cats is fluticasone propionate (Flovent®); Flovent is used for long-term control of airway inflammation (takes 10–14 days to reach peak effect; during this time steroids administered by mouth will be used as well)
Other Drugs
Medications to enlarge or dilate the bronchi and bronchioles (bronchodilators), such as sustained release theophylline
β-2 agonists (terbutaline, albuterol)—these reverse smooth muscle constriction to dilate the bronchi and bronchioles
Inhaled bronchodilators—albuterol is the preferred inhalant therapy in cats, providing immediate relief of spasm and constriction of the bronchi—its effect lasts less than 4 hours
Medications to kill intestinal parasites (known as “anthelminthics”)—routinely recommended for cats with clinical signs of feline bronchopulmonary disease, with predominantly eosinophils found on microscopic examination of material obtained from the lower airways; parasitic inflammation of the bronchi and bronchioles (bronchitis) can be difficult to diagnose—treatment is indicated with appropriate clinical signs and geographic location; appropriate medication will depend on specific parasite suspected in the geographic region; examples include fenbendazole, ivermectin, or praziquantel
Antibiotics—choice of antibiotic based on bacterial culture and sensitivity testing
Follow-Up Care
Patient Monitoring
Report any increase in coughing, sneezing, wheezing, or breathing distress; medications should be increased appropriately if clinical signs worsen, as directed by your pet's veterinarian
Follow-up x-rays (radiographs) may be helpful to evaluate response to medical treatment or onset of new disease
Watch for signs of increased urination (known as “polyuria”) and increased thirst (known as “polydipsia”) that may indicate diabetes mellitus or kidney disease
Monitor blood glucose levels
Monitor urine (urinalysis, bacterial culture and sensitivity) as urinary tract infections can occur as a complication of certain treatments
Preventions and Avoidance
Eliminate any environmental factors (such as cigarette smoke, dusty cat litter, hair sprays, and air fresheners) that may trigger a crisis situation
Consider dust-free cat litter
Change furnace and air-conditioner filters on a regular basis
Possible Complications
Sudden (acute) episodes can be life-threatening
Right-sided heart disease rarely develops as a result of long-term inflammation of the bronchi and bronchioles (bronchitis)
Expected Course and Prognosis
Long-term therapy should be expected
Most cats do well, if recurrence of clinical signs is monitored carefully and medical therapy is adjusted appropriately
A few cats will not respond to medical treatment; these cats carry a much worse prognosis
Key Points
Most affected cats have long-term (chronic) and progressive disease
Sudden (acute) episodes can be life-threatening
Lifelong medication and environmental changes usually are necessary, as directed by your pet's veterinarian
