An 11 month old male domestic long hair feline presented for a 1 week history of acute onset of elevated third eyelids, decreased appetite and liquid diarrhea. Two days prior to presentation, he developed vomiting and exaggerated swallowing. He was anorexic for 24 hours prior to presentation. Referral lab work was unremarkable and a total T4 was normal at 1.3 ug/dL. A Felv and FIV test was negative, and a spec fPL was normal. On presentation, the patient appeared quiet but responsive, bradycardic at 100 beats per minute, and had bilateral third eyelid elevations. Mydriasis was noted bilaterally, ambulation was weak, and anal tone was absent. An abdominal ultrasound showed a moderately dilated stomach and moderately dilated urinary bladder with the remainder of the abdomen being unremarkable. Based on his clinical signs as well as physical examination findings, Key-Gaskell syndrome was suspected. Further diagnostics were performed to help confirm this diagnosis. A STT was negative OU and he had a positive pilocarpine response OU as his mydriasis and third eyelid elevation resolved. An EKG showed sinus bradycardia and a doppler blood pressure was normal. Thoracic radiographs showed a megaesophagus.
Unfortunately, cats with Key-Gaskell syndrome have a very guarded prognosis as their clinical signs continue to progress in spite of supportive medical care. The owners elected to implement treatment with cisapride and bethanechol in hopes of improving the patient’s clinical signs.
Key-Gaskell is also known as dysautonomia. Dysautonomia is a polyneuropathy of the autonomic nervous system affecting both sympathetic and parasympathetic ganglia. Animals with this condition may have a rapid onset (within a few hours) or a gradual onset (over several weeks) of clinical signs. Signs suggestive of this condition include vomiting or regurgitation, diarrhea or occasionally constipation, stranguria, urinary incontinence, mydriasis causing photophobia, xerostomia, elevated third eyelids, coughing, depression, weakness, anorexia, and weight loss. Typically, motor, sensory, and behavioral functions are not affected.
Diagnosis is typically based on physical examination findings, radiographic findings, as well as pharmacologic testing. Radiographic abnormalities suggestive of Key-Gaskell include aspiration pneumonia, megaesophagus, dilated stomach, diffuse ileus, and a distended urinary bladder. Pharmacologic testing could include a diluted pilocarpine 0.05% test that does not alter a normal animal but will induce miosis and retraction of third eyelid elevations in an affected animal. An atropine response test would show no improvement in bradycardia in an affected animal. A schirmer tear test would indicate absent tear production or tear production <5 mm/min. An intradermal histamine response test is another diagnostic, however, this test is rarely performed given the high risk for ventricular arrhythmias.
There is no specific treatment for dysautonomia except for supportive care. Prokinetic drugs could be considered such as metoclopramide or cisapride and cholinergic drugs such as bethanechol could be initiated if the patient is dealing with urinary retention. Pilocarpine or other parasympathomimetics may be used to treat mydriasis. Warm air humidifiers and artificial tears/genteal gel may be helpful in keeping ocular and respiratory mucous membranes moist.
Prognosis is very guarded and mortality rate is high. Aspiration pneumonia is a common complication and potentially cause of death with this disease. If an animal does survive, it may never completely recover.