Page 484 - Small Animal Internal Medicine, 6th Edition

456 PART III Digestive System Disorders

some prokinetic activity. Sucralfate (particularly suspen- DYSAUTONOMIA
sions) might protect denuded esophageal mucosa if there is Etiology
VetBooks.ir gastroesophageal reflux (see Table 28.5), but its main value Dysautonomia in dogs and cats is an idiopathic condition
is to provide some analgesia for the discomfort of the esoph-
that causes loss of autonomic nervous system function. In at
agitis. For dogs in a lot of pain that will not even swallow
their saliva, viscous lidocaine, which is available over the least some circumstances (e.g., Key-Gaskell syndrome of
counter, may be administered orally. Antibiotics are of cats), it might be due to a clostridial toxin.
dubious value. In exceptional cases, a gastrostomy feeding
tube protects the esophagus while the mucosa is healing and Clinical Features
ensures a positive nitrogen balance. Glucocorticoids may be Clinical signs vary substantially. Megaesophagus and subse-
administered in an attempt to prevent cicatrix, but there is quent regurgitation are common but not invariable. Dysuria
no evidence that they are effective Symptomatic hiatal and a distended urinary bladder, mydriasis and lack of pupil-
hernias may have to be surgically repaired. lary light response, dry mucous membranes, weight loss,
Proton pump inhibitors and prokinetics may be admin- constipation, vomiting, poor anal tone, and/or anorexia have
istered prophylactically to lessen anesthesia-associated reflux all been reported.
with subsequent esophagitis. Although such therapy lessens
the frequency of acid reflux, it does not abolish it. Diagnosis
Dysautonomia is usually first suspected clinically by finding
Prognosis dysuria, dry mucous membranes, and abnormal pupillary
The prognosis depends on the severity of the esophagitis light responses. Radiographs revealing distention of multiple
and whether an underlying cause can be identified and areas of the alimentary tract (e.g., esophagus, stomach, small
controlled. Early aggressive therapy helps prevent cicatrix intestine) also are suggestive. A presumptive antemortem
formation. diagnosis is usually made by observing the effects of pilocar-
pine on pupil size after 1 to 2 drops of 0.05% pilocarpine are
HIATAL HERNIA placed in one eye only. Finding that the treated eye rapidly
constricts whereas the untreated eye does not is consistent
Etiology with dysautonomia. Similarly, finding that a dysuric dog with
Hiatal hernia is a diaphragmatic abnormality that allows part a large urinary bladder can urinate after subcutaneous
of the stomach (usually the cardia) to prolapse into the tho- administration of 0.04 mg bethanechol/kg is also suggestive
racic cavity. It may also allow gastroesophageal reflux. (although not all affected animals respond). Definitive diag-
nosis requires histopathology of autonomic ganglia obtained
Clinical Features at necropsy.
Brachycephalic breeds seem predisposed to this disorder.
Regurgitation is the primary sign in symptomatic individu- Treatment
als, but some animals are asymptomatic. Treatment is palliative. Bethanechol can be given (2.5-15 mg
once daily) to aid in urinary evacuation. The urinary
Diagnosis bladder should be expressed as needed. Gastric prokinet-
Plain radiographs or positive-contrast esophagrams may ics (e.g., cisapride) may help lessen vomiting. Antibiotics
reveal gastric herniation into the thorax (Fig. 29.4); however, may be administered for aspiration pneumonia secondary
herniation may be intermittent and difficult to detect. Manu- to megaesophagus.
ally putting pressure on the abdomen while taking a radio-
graph may cause displacement of the stomach into the thorax Prognosis
during the study. Hiatal hernias are occasionally found endo- The prognosis is usually grim.
scopically, but the endoscopic appearance can be subtle and
is easily missed by novice endoscopists. ESOPHAGEAL OBSTRUCTION

Treatment VASCULAR RING ANOMALIES
If the hiatal hernia is symptomatic at an early age, surgery is Etiology
more likely to be required to correct it. If clinical signs of
hiatal hernia first appear later in life, aggressive medical Vascular ring anomalies are congenital defects. An embry-
management of gastroesophageal reflux (e.g., cisapride, onic aortic arch persists, trapping the esophagus in a ring of
omeprazole) is sometimes sufficient. If medical management tissue. Persistent right fourth aortic arch (PRAA) is the most
is unsuccessful, surgery can be considered. commonly recognized vascular anomaly (see Chapter 5).

Prognosis Clinical Features
The prognosis is often good after surgical repair (congenital Vascular ring anomalies occur in dogs and cats. Regurgita-
cases) or aggressive medical management (acquired cases). tion is the most common presenting complaint, although