Page 306 - Small Animal Internal Medicine, 6th Edition

278 PART II Respiratory System Disorders

BOX 18.1 BOX 18.2
VetBooks.ir Potential Causes of Laryngeal Paralysis Diagnostic Evaluation of Dogs and Cats With Confirmed
Laryngeal Paralysis
Idiopathic
Ventral Cervical Lesion Underlying Cause
Trauma to nerves Thoracic radiographs
Direct trauma Cervical radiographs
Inflammation Serum biochemical panel
Fibrosis Thyroid hormone evaluation
Neoplasia Ancillary tests in select cases
Other inflammatory or mass lesion Evaluation for polyneuropathy-polymyopathy
• Electromyography
Anterior Thoracic Lesion • Nerve conduction measurements
Neoplasia Antinuclear antibody test
Trauma Antiacetylcholine receptor antibody test
Postoperative
Other Concurrent Pulmonary Disease
Other inflammatory or mass lesion Thoracic radiographs
Polyneuropathy and Polymyopathy Concurrent Pharyngeal Dysfunction
Idiopathic Evaluation of gag reflex
Immune mediated Observation of patient swallowing food and water
Endocrinopathy Fluoroscopic observation of barium swallow
Hypothyroidism
Other systemic disorder Concurrent Esophageal Dysfunction
Toxicity Thoracic radiographs
Congenital disease Contrast-enhanced esophagram
Fluoroscopic observation of barium swallow
Myasthenia Gravis

during inspiration and may open slightly during expiration. partial laryngectomy, and castellated laryngoplasty. The goal
The larynx does not exhibit the normal coordinated move- of surgery is to provide an adequate opening for the flow of
ment associated with breathing, opening on inspiration and air but not one so large that the animal is predisposed to
closing on expiration. Additional laryngoscopic findings aspiration and the development of pneumonia. Several oper-
may include laryngeal edema and inflammation. The larynx ations to gradually enlarge the glottis may be necessary to
and the pharynx are also examined for neoplasia, foreign minimize the chance of subsequent aspiration. The recom-
bodies, or other disorders that might interfere with normal mended initial procedure for most dogs and cats is unilateral
function and for laryngeal collapse (see Chapter 17). arytenoid lateralization.
Once a diagnosis of laryngeal paralysis has been estab- If surgery is not an option, medical management consist-
lished, additional diagnostic tests should be considered to ing of antiinflammatory doses of short-acting glucocorti-
identify underlying or associated diseases (particularly if the coids (e.g., prednisone, 0.5 mg/kg given orally q12h initially)
patient is an atypical breed), to identify concurrent aspira- and cage rest may reduce secondary inflammation and
tion pneumonia, and identify concurrent pharyngeal and edema of the pharynx and larynx and enhance airflow. For
esophageal motility problems (Box 18.2). long-term management, situations resulting in prolonged or
increased breathing efforts, such as heavy exercise, and high
Treatment ambient temperatures are avoided. Exercise may need to be
In animals with respiratory distress, emergency medical limited to leash walks or other routines where the intensity
therapy to relieve upper airway obstruction is indicated (see of activity is controlled. Trazadone can be considered for
Chapter 25). Following stabilization and a thorough diag- highly excitable dogs.
nostic evaluation, surgery is usually the treatment of choice.
Even when specific therapy can be directed at an associated Prognosis
disease (e.g., hypothyroidism), complete resolution of clini- The overall prognosis for dogs with laryngeal paralysis
cal signs of laryngeal paralysis is rarely seen. treated surgically is fair to good, despite evidence for pro-
Various laryngoplasty techniques have been described, gressive, generalized disease, esophageal dysfunction, or
including arytenoid lateralization (tie-back) procedures, aspiration pneumonia. Wilson et al. (2016) showed that