Page 364 - Small Animal Internal Medicine, 6th Edition

336 PART II Respiratory System Disorders

examination, cardiac evaluation, and screening for systemic described for canine chronic bronchitis. Any other poten-
disease. tially related problems identified during the diagnostic eval-
VetBooks.ir Treatment uation are addressed.
A novel approach to treating TBM as reported by
Medical therapy is adequate treatment for most animals. In
tracheal wall strength, but this treatment has not been widely
a study of 100 dogs by White et al. (1994), medical therapy Adamama-Moraitou et al. (2012) uses stanozolol to improve
resulted in resolution of signs for at least 1 year in 71% of adopted. Possible mechanisms include enhanced protein or
cases. Dogs that are overweight are placed on a weight- collagen synthesis, increased chondroitin sulfate content,
reducing diet. Harnesses should be used instead of collars, increased lean body mass, and decreased inflammation.
and owners should be counseled to keep their dogs from Dogs with tracheal collapse, but not bronchitis, were treated
becoming overheated (e.g., they should not be left in a car). with 0.3 mg/kg stanozolol divided twice daily for 2 months
Excessive excitement should be avoided. Sedatives such as orally, then tapered for 15 days. Dogs in the stanozolol group
phenobarbital are prescribed for some animals for short- had improved clinical signs by some measures after 30 days,
term use, and these can be administered before known and improvement in grade of collapse was seen on tracheos-
stressful events. In some patients, anxiolytic drugs such as copy at 75 days.
trazadone may be beneficial for prolonged management. Management of dogs in acute distress with signs of either
Cough suppressants are used to control signs and to extrathoracic airway obstruction or intrathoracic large
disrupt the potential cycle of perpetuating cough (see Table airway obstruction is discussed in Chapter 25.
21.1). The dose and frequency of administration of cough Tracheal stenting should be considered for dogs with
suppressants are adjusted as needed. Initially, high, frequent TBM that cannot effectively ventilate due to airway obstruc-
dosing may be needed to break the cycle of coughing. Sub- tion despite aggressive medical management. Stenting can
sequently, it is often possible to decrease the frequency of also be attempted in dogs with refractory cough, but the
administration and the dose. For refractory cases, the addi- outcome for this use is often unsatisfactory. The introduc-
tion of maropitant or gabapentin is an option. The cough tion of intraluminal tracheal stents has greatly reduced the
suppressant effect of maropitant may not be apparent for 1-2 morbidity and improved the success of surgical interven-
weeks (Grobman and Reinero, 2016). Gabapentin has been tion. The most commonly used stents are self-expanding and
used to aid in the control refractory chronic cough in people made of nickel-titanium alloys (Fig. 21.8). In experienced
through mechanisms similar to interfering with neuropathic hands, these stents are simple to place during a short period
pain (Ryan, 2015). of anesthesia under fluoroscopic or bronchoscopic guidance.
Antiinflammatory doses of glucocorticoids can be given Minimal morbidity is associated with stent placement, and
for a short period during exacerbation of signs (prednisone, response is immediate and often dramatic. However, clini-
0.5-1 mg/kg orally q12h until signs have subsided, then cal signs may not completely resolve, collapse of airways
tapered and discontinued over 3-4 weeks). Long-term use is beyond the trachea and concurrent conditions are not
ideally avoided to prevent potential detrimental side effects directly addressed (nearly always resulting in the continued
such as obesity but is often necessary to control signs, need for medical management), and complications such as
particularly in patients with chronic bronchitis. Inhaled infection, ingrowth of tissue, and stent fracture can occur. In
corticosteroids can be tried if a positive therapeutic response particular, cough is usually significantly worse in the weeks
is seen to minimize systemic side effects.
Bronchodilators may be beneficial in dogs with concur-
rent chronic bronchitis. Beneficial effects are likely attribut-
able to antiinflammatory effects, enhancement of steroid
activity, or improved mucociliary clearance rather than from
bronchodilation. The use of glucocorticoids and bronchodi-
lators for treatment of inflammatory airway disease is dis-
cussed in more detail in the sections on canine chronic
bronchitis and feline bronchitis.
Dogs with signs referable to mitral insufficiency are
managed for this disease (see Chapter 6). Dogs with abnor-
malities causing upper airway obstruction are treated with
corrective surgical procedures.
Antibiotics are not indicated for the routine management
of TBM. Dogs in which tracheal wash or BAL fluid analysis
has revealed evidence of infection should be treated with FIG 21.8
appropriate antibiotics (selected on the basis of the results of Lateral radiograph of the dog with tracheal collapse (shown
sensitivity testing). Because most antibiotics do not reach in Fig. 21.6) after placement of an intraluminal stent. The
high concentrations in the airways, relatively high doses of stent has a mesh-like structure and extends nearly the entire
antibiotics should be administered for several weeks, as length of the trachea.