Page 102 - Problem-Based Feline Medicine

94 PART 2 CAT WITH LOWER RESPIRATORY TRACT OR CARDIAC SIGNS

● Pulmonary function testing includes spirometry, ● Terbutaline 0.01 mg/kg SQ will usually result in
whole-body plethysmography and tidal breathing bronchodilation within 10–15 mins; for longer term
flow–volume loops (TBFVL). Increased airway therapy it can be administered orally (0.1 mg/kg PO
resistance with aerosol challenge, and decreased q 12 h (1/4 – 1/2 × 2.5 mg tablet) or inhaled
resistance with bronchodilator therapy are diagnos- (Brethine). In a crisis, it can be given IV (0.01
tic of asthma. This testing is rarely available outside mg/kg IV q 30 min for up to 4 h) until a response is
of teaching or research institutions. observed, or by inhalation.
● Asthma is differentiated from bronchitis on the basis ● Inhalant bronchodilators (beta -adrenergic ago-
2
of a positive response to an inhaled bronchodilator nists such as terbutaline (Brethine), albuterol
with asthma. [also known as salbutamol] (Proventil, Ventolin)
may be used in a crisis situation (q 30 min repeated
for 2–4 h) with an effect seen in 5–10 min. This
Differential diagnosis route is more effective than IM, SC, or oral admin-
istration. They are administered using a spacer
Main differential for status asthmaticus is acute con-
chamber attached to the metered dose inhaler at one
gestive heart failure, usually due to cardiomyopathy,
end and a face mask at the other end. Aerokat®
although cats with heart failure rarely cough.
(www.aerokat.com) mask and spacer chamber is
Other respiratory diseases, such as upper airway made specifically for cats, or ones made for infants
obstruction (laryngeal paralysis), pulmonary disease such as the Pocket Chamber® combined with the
(pneumonia, neoplasia), and pleural space disease may smallest Panda Mask® (Ferraris Medical Inc) can
also cause chronic coughing. be used to deliver drug inhalant therapy. Empty toi-
let paper rolls or paper coffee cups have also been
used successfully as spacing chambers in cats. Two
Treatment “puffs” or metered doses of the bronchodilator is
used to fill the spacer chamber, and the mask is gen-
Status asthmaticus – oxygen supplementation is
tly placed over the cat’s mouth and nose while the
required during respiratory distress. An O chamber or
2 cat breathes 10–15 times (approx 30–45 secs).
tent is best tolerated by air-starved patients. Use
There are several anecdotal reports of success, lead-
injectible terbutaline (0.01 mg/kg SQ), and dexam-
ing to weaning off systemic drug dosages or
ethasone (0.25–0.5 mg/kg IV or IM), and in severe
decreasing severity and frequency of attacks.
cases, epinephrine (0.5 ml 1:10 000) SQ as a bron-
Albuterol is reported to be rapid acting, and may be
chodilator. Minimal handling and restraint of acutely
used in an emergency situation, or for chronic ther-
dyspneic patients is essential.
apy q 12 h as needed (prn). Salmeterol [Serevent]
Asthma has a slower onset and a 12 hour duration, and can
● As this is a bronchoconstrictive disorder, it be used for chronic therapy. Adverse effects of
responds more briskly to bronchodilators. beta -adrenergic agonists are musculoskeletal
2
● Bronchodilators seem to have a synergistic effect twitchiness, excitability, insomnia, and anorexia,
when used with steroids, or when two classes of but are very rare in cats, suggesting these drugs
bronchodilator are combined. have a high safety margin in cats.
● Sustained release theophylline 25 mg/kg PO q 24 h
Bronchitis
or 10 mg/kg PO q 12 h. Consistent pharmacokine-
● As this is an inflammatory disease, anti-inflamma-
tics have only been demonstrated with a few prod-
tories, and perhaps leukotriene inhibitors and mast
ucts (Theo-Dur® (Key Pharmaceuticals), Slo-Bid
cell stabilizing agents are more indicated for long-
Gyrocaps® (Rhone-Poulene Rorer Labs), and
term therapy.
Theocap ER® and Theochron ER® (Inwood
Bronchodilators Laboratories or Forest Laboratories), and the first
Bronchodilators are an important part of therapy for two are unavailable in the US. Theochron ER®
asthmatic cats, and can be administered orally, tablets can only be broken along the scored line into
parentally or by inhalation. half, and Theocap ER® capsules can be opened