Page 300 - Small Animal Internal Medicine, 6th Edition

272 PART II Respiratory System Disorders

Heat
Excitement ↑ Effort BOX 16.1
Exercise
VetBooks.ir Differential Diagnoses for Laryngeal Disease in Dogs
and Cats

Laryngeal paralysis
Laryngeal neoplasia
↑ Obstruction ↑ Intraluminal Obstuctive laryngitis
pressures
Laryngeal collapse
Web formation
Trauma
FIG 16.1 Foreign body
Patients with extrathoracic (upper) airway obstruction often
present in respiratory distress as a result of progressive Extraluminal mass
worsening of airway obstruction after an exacerbating event. Acute laryngitis

in the pharynx, such as an elongated soft palate or mass,
causes turbulent airflow. Reverse sneezing (see Chapter 13),
gagging, or retching may result from local stimulation from BOX 16.2
the tissue itself or from secondary secretions. Dysphagia
results from physical obstruction, usually caused by a mass. Differential Diagnoses for Pharyngeal Disease in Dogs
As with laryngeal disorders, a definitive diagnosis is made and Cats*
through a combination of visual examination, radiography, Brachycephalic airway syndrome
and biopsy of abnormal tissue. Visual examination includes Elongated soft palate
a thorough evaluation of the oral cavity, larynx, and caudal Nasopharyngeal polyp
nasopharynx. In some cases, fluoroscopy or CT scan may be Foreign body
necessary to assess abnormalities visible only during the Neoplasia
stress of labored breathing or to assess mass lesions resulting Abscess
in external compression of the airway, respectively. Granuloma
Extraluminal mass
DIFFERENTIAL DIAGNOSES FOR Nasopharyngeal stenosis
LARYNGEAL SIGNS IN DOGS AND CATS
*Upper airway obstruction resulting from extra-thoracic tracheal
collapse can mimic obstruction resulting from pharyngeal disease.
Differential considerations for dogs and cats with respiratory
distress are discussed in Chapter 25.
Dogs are more commonly presented for laryngeal disease airway syndrome, which is discussed in Chapter 18, but it
than cats and usually have laryngeal paralysis (Box 16.1). can also occur in nonbrachycephalic dogs. Nasophparyngeal
Laryngeal neoplasia can occur in dogs or cats. Obstructive polyps are the most common pharyngeal disease in cats,
laryngitis is a poorly characterized inflammatory disorder. followed by neoplasia. Nasopharyngeal polyps, nasal tumors,
Other possible diseases of the larynx include laryngeal col- and foreign bodies are discussed in the chapters on nasal
lapse (see Laryngoscopy, Chapter 17), web formation (i.e., diseases (see Chapters 13 to 15). Other differential diagnoses
adhesions or fibrotic tissue across the laryngeal opening, are abscess or granuloma and compression caused by an
usually as a complication of surgery), trauma, foreign body, extraluminal mass. Nasopharyngeal stenosis can occur as a
and compression caused by an extraluminal mass. Acute complication of chronic inflammation (rhinitis or pharyngi-
laryngitis is not a well-characterized disease in dogs or cats tis), vomiting, or gastroesophageal reflux in dogs or cats.
but presumably could result from viral or other infectious Dogs with tracheobronchomalacia (see Chapter 21) who are
agents, foreign bodies, or excessive barking. Gastroesopha- presented for signs of upper airway obstruction resulting
geal reflux, a cause of laryngitis in people, has recently been from extrathoracic tracheal collapse can have loud, sterto-
documented to cause laryngeal dysfunction in a dog (Lux, rous breathing similar to that heard in dogs with brachyce-
2012). phalic airway syndrome. The difference in breed predisposition
for these two conditions assists in prioritizing the differential
DIFFERENTIAL DIAGNOSES FOR diagnoses.
PHARYNGEAL SIGNS IN DOGS
AND CATS Suggested Readings
Hunt GB, et al. Nasopharyngeal disorders of dogs and cats: a review
The most common pharyngeal disorders in dogs are brachy- and retrospective study. Compendium. 2002;24:184.
cephalic airway syndrome and elongated soft palate (Box Lux CN. Gastroesophageal reflux and laryngeal dysfunction in a
16.2). Elongated soft palate is a component of brachycephalic dog. J Am Vet Med Assoc. 2012;240:1100.