Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Two The Thorax 235
Fig. 2-224 A 12-year-old spayed
female mixed breed dog was evaluated
for panting and gagging. A palpable
mass was present in the
laryngeal region. Longitudinal (A)
and transverse (B) sonograms
revealed a mass (*) with complex
architecture on both sides of the trachea
(arrow). The area distal to the
trachea on the transverse view is
obscured by air in the trachea.
Diagnosis: Thyroid carcinoma.
A
B
Fig. 2-225 A 12-year-old spayed
female domestic short-haired cat
evaluated for a cervical swelling of 2
weeks duration. The longitudinal
(A) and transverse (B) sonograms
reveal an enlarged thyroid gland that
contains an irregularly shaped anechoic
structure (arrow). Diagnosis:
Thyroid hyperplasia with cyst formation.
A
B
Feline hyperthyroidism is typified by diffuse but not massive enlargement of one or
both thyroid glands. Focal areas of enlargement may be seen in some individuals.
Sonography has been used to define size and determine if cystic areas are present within
the glands (Fig. 2-225). 655
Sonography also has been used to identify enlarged parathyroid glands. 36-38,656
Abnormal glands were enlarged when compared with others in the opposite thyroid and
were markedly hypoechoic (Fig. 2-226).
SWALLOWING DISORDERS
Swallowing is a complex event that involves the pharynx, larynx, and esophagus. It cannot
be evaluated without contrast administration and almost always requires a dynamic examination
using cinefluoroscopy or videofluoroscopy. The events must be examined slowly
and repeatedly before a definite diagnosis can be reached. An esophagram with a single
radiograph or series of radiographs may identify the site (i.e., oral, pharyngeal or
esophageal) of the abnormality, but it rarely defines the functional problem. Therefore,
patients with oral or pharyngeal dysphagia should be referred to hospitals that have fluoroscopic
equipment.
Retention of food or barium in the oral pharynx suggests an oropharyngeal disorder.
Contrast or food in the nasal pharynx may indicate the failure of the soft palate to close the
nasal pharynx or it may indicate incoordination between pharyngeal muscle contraction
and dorsal movement of the soft palate. Abnormal cricopharyngeal muscular activity may
produce a cricopharyngeal achalasia, or failure of the muscle to relax; chalazia, or failure to
contract with resulting sphincter incompetence; or incoordination between the pharyngeal
muscle contraction and cricopharyngeal muscle relaxation. Aspiration of food or barium
may indicate a lack of normal laryngeal movement, incoordination between the pharyngeal