The use of bronchodilators, including albuterol, is based on the assumption that clinically significant bronchoconstriction
is evident. Cats develop naturally occurring and clinically significant bronchoconstriction that in severe cases can be life-threatening.
Bronchodilator drugs can be beneficial to these cats. These drugs are classified generally as beta-receptor agonists, methylxanthine
derivatives, or anti-cholinergics.
Albuterol is a selective beta2-receptor agonist that produces relaxation of the smooth muscle found principally in bronchial,
vascular and uterine tissues. The exact mechanism by which activation of beta2 (beta-2) receptors results in smooth-muscle
relaxation is not totally understood, but it likely involves intracellular cAMP induced suppression of the kinase controlling
myosin and actin interaction.
At usual doses, albuterol has little effect on beta1 (beta-1) receptors; hence, direct cardiostimulatory effects are minimal.
However, albuterol should always be used with care in cats that may have increased sensitivity to adrenergic agents — in particular,
cats with pre-existing cardiac disease, diabetes mellitus, hyper-thyroidism, hypertension or seizure disorders.
All beta-2 agonists may lower plasma potassium; hence, it may be prudent to monitor serum potassium levels in at-risk cats
receiving long-term albuterol therapy. In clinical practice, it is uncommon to find beta-2 agonist associated hypokalemia
When albuterol is used with other sympathomimetics, the risk of adverse cardiovascular effects increase, as does its concurrent
use with digoxin, tricyclic antidepressants and monoamine oxidase inhibitors. These potential effects are more likely in cats
with pre-existing cardiac disease, especially hypertrophic cardiomyo-pathy. Use with various inhalation anesthetics may predispose
the cats to ventricular arrhythmias.
Albuterol is available as a tablet, syrup and is contained in various inhalants. The inhaled form comes as a single-strength,
17-gram metered dose inhaler and delivers 90 mcg per actuation of the device.
The pharmacokinetic profile of albuterol in cats has not been reported. When administered by inhalation, albuterol produces
significant bronchodilation within 15 minutes that lasts three to four hours. It is well absorbed orally and may have bronchodilatory
effects for up to eight hours. Anecdotal experience with this drug in clinical practice suggests a similar pharmacokinetic
profile in cats. Albuterol can be used once daily prior to administering fluticasone or as needed for acute coughing and wheezing.
In emergency cases, albuterol can be used every 30 minutes for up to four to six hours without serious side effects.
Albuterol undergoes extensive hepatic metabolism. After oral administration, 58 percent to 78 percent of the dose is excreted
in the urine over 24 hours, with 60 percent in an inactive form.
Rarely, adverse effects include mild skeletal muscle tremors and restlessness, which generally subside in two to three days.
The use of inhaled medications to treat asthma and bronchitis is considered the standard of care in cats with chronic bronchial
disease. This approach avoids many of the side effects previously seen in cats treated with systemic medications.
Dr. Hoskins is owner of Docu-Tech Services. He is a diplomate of the American College of Veterinary Internal Medicine with specialities
in small animal pediatrics. He can be reached at (225) 955-3252, fax: (214) 242-2200 or e-mail: firstname.lastname@example.org