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276.e2 Dysautonomia

Dysautonomia
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• Coughing
BASIC INFORMATION
rhinitis
• Weight loss ○ Respiratory: any cause of pneumonia or
Definition
Dysautonomia is characterized by degenera- PHYSICAL EXAM FINDINGS Initial Database
tion of the autonomic ganglia, with failure of • Diminished anal sphincter tone • Neurologic exam (p. 1136): rule out behavior,
parasympathetic and sympathetic function in • Dry eyes and mucous membranes, with motor, or sensory deficits
multiple organs. It is common in some areas normal hydration; crusty nose • CBC, serum biochemistry panel, urinalysis:
of the United States (e.g., Kansas, Missouri, • Midrange or dilated pupils with no pupillary unremarkable unless complication (e.g.,
Oklahoma). light reflex but normal vision pneumonia)
• Elevated third eyelid, enophthalmos, and • Radiographs may reveal evidence of ileus,
Synonym ptosis distended bladder, megaesophagus, and/or
Key-Gaskell syndrome • Distended, easily expressed bladder aspiration pneumonia.
• Abdominal discomfort • Abdominal ultrasound or barium series may
Epidemiology • Heart rate and blood pressure are usually at show lack of intestinal motility.
SPECIES, AGE, SEX the low end of normal range. • Ocular pilocarpine test will rule out anti-
• In the United States, dogs are most com- • Nasal discharge or crackles on lung aus- cholinergic toxicosis in animals with dilated
monly affected; occasional feline cases. In the cultation if secondary rhinitis or aspiration pupils.
United Kingdom, horses are most commonly pneumonia ○ Place 2-3 drops of 0.05% pilocarpine (1%
affected. • Cachexia can be dramatic even in relatively diluted 1 : 20 with saline or eye flush) in
• Animals of any age may be affected, but short-duration disease. one eye.
dysautonomia most commonly affects young ○ Compare pupil size q 15 minutes for up
adult dogs (median age, 18 months). Etiology and Pathophysiology to 1 hour.
• Histologically, there is loss of neurons in the ○ Pupil should constrict in dysautonomia;
RISK FACTORS autonomic ganglia with little inflammation. no response with anticholinergic toxicosis
Free-roaming, rural dogs are at higher risk. • Cause is unknown. or normal pupil
• Atropine response test: does not rule out
CONTAGION AND ZOONOSIS DIAGNOSIS anticholinergic toxicosis but documents
• Except for rare reports of multiple dogs in a cardiac involvement.
household affected, no evidence of contagion Diagnostic Overview ○ Measure heart rate before and 15-30
• No evidence of zoonosis • To establish the diagnosis, it is necessary minutes after atropine 0.04 mg/kg IV.
to document autonomic failure in multiple ○ Rate should increase in normal animal;
GEOGRAPHY AND SEASONALITY organs without significant deficits in sensory may not change in dysautonomia.
• In the United States, the greatest concentra- or motor function. Not all patients show all
tion of dysautonomia centers on the borders clinical signs. Advanced or Confirmatory Testing
between Missouri, Kansas, and Oklahoma. • Dysautonomia can mimic other diseases • Cardiac ultrasound may show reduced
Cases are also seen in the northern Colorado in the early stages when only one or two fractional shortening.
and southern Wyoming front ranges, with autonomic functions are affected. • Diagnosis can be confirmed at necropsy by
occasional cases elsewhere in the country. cell loss and gliosis in autonomic ganglia on
• Most common in late winter/early spring; Differential Diagnosis histopathologic exam. The celiacomesenteric
lower incidence in summer • The most dramatic signs reflect parasym- ganglia can be found surrounding the origin
pathetic loss, and anticholinergic toxicosis of the cranial mesenteric artery from the
ASSOCIATED DISORDERS needs to be ruled out. aorta, and there are usually autonomic
Autonomic failure can be a part of a more • Other differentials are based on the organ ganglia in the periadrenal tissues.
diffuse peripheral neuropathy or neuromuscular system most prominently affected.
junction disorder. ○ GI: gastroenteritis, GI foreign body, meta- TREATMENT
bolic causes, idiopathic megaesophagus,
Clinical Presentation focal myasthenia gravis Treatment Overview
DISEASE FORMS/SUBTYPES ○ Dry eyes and mucous membranes: Because the cause is unknown, treatment is
• Different combinations of organ failure may dehydration, keratoconjunctivitis sicca supportive and dictated by the signs shown.
be seen. (eyes only)
• Dogs in the early stage of disease may have ○ Dilated pupils: intraocular or retrobulbar Acute and Chronic Treatment
only one obvious sign (e.g., dilated pupils, disease • GI prokinetic drugs (metoclopramide or
gastrointestinal [GI] atony). Other signs rapidly ○ Photophobia: corneal ulcer or anterior cisapride)
develop, allowing a diagnosis of dysautonomia. uveitis • Eye lubrication
○ Elevated third eyelid, enophthalmos and • Humidification of air
HISTORY, CHIEF COMPLAINT ptosis: any cause of Horner’s syndrome, • Manually express the bladder. Low-dose
Acute disease: most cases < 5-14 days duration: especially retrobulbar, mediastinal, or bethanechol may help bladder contraction
• Most common complaint is GI disturbance: middle ear disease but may cause increased vomiting.
vomiting/regurgitation and diarrhea; some- ○ Dysuria: urinary tract infection, disease • Antibiotics for secondary infections
times constipation affecting sacral spinal cord, cauda equina, • Pimobendan if poor cardiac contractility
• Dysuria or pelvic nerves
• Photophobia, dilated pupils, or third eyelid ○ Loss of anal sphincter tone: disease affect- Nutrition/Diet
elevation can occur ing sacral spinal cord, cauda equina, or Support nutrition and hydration:
• Nasal discharge pudendal nerves • IV fluids
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