Dysautonomia in Dogs and Cats?
Before we dive into this topic, I wanted to report the diagnosis for the case from last week's TidBit Tuesday mailer. The cat with the C6-T2 myelopathy was diagnosed with an FCE and was managed successfully over about 2 months to an almost normal return to function.
Now, on to this week's TidBit Tuesday...
Several of us worked on an interesting case together this week that tickled my memory about a disease that we, in Wisconsin, do not see very often. I thought we could all refresh together.
Dysautonomia is (typically) caused by degeneration of the autonomic, and some somatic, nerve cell bodies throughout the spinal cord and some brainstem nuclei.
Common Clinical Signs
With this disease, you may see vomiting first, followed by dysuria (enlarged bladder that is easy to express but difficult to void by the patient). One of the hallmark signs is a loss of anal tone and THIS IS SOMATIC not autonomic. We can see a mix of lower motor neuron signs with autonomic loss in this disease! Absent PLR and elevated 3rd eyelid are common findings on physical examination. From there, you may diagnose megaesophagus and ileus on radiographs.
Diagnosis
A study by Dr. Berghaus et al in 2001 identified that dysautonomia was found more often in rural areas, with access to water or farm land. Additionally, all of the published US cases have been from Missouri/southern Illinois region.
This disease is diagnosed through pharmacological testing and elimination of other etiology. In Dr. Berghaus' study, the Schirmer tear test was below 5 mm/min in 50% (20) of dogs, between 5-10 mm/min in an 10 additional dogs. There was no response to an atropine response test in many dogs, and some response in a few cases. Finally, most dogs had a rapid response to dilute pilocarpine in the eye, but not all. All of these tests are looking at the autonomic system in different areas of the body. When a reduced response to one or more of these tests is noted, taking into account the clinical history, you may wish to consider dysautonomia as a diagnosis.
Unfortunately, there is no known treatment that will reverse clinical progression. A combined immune mediated dysautonomia, and myasthenia gravis has been reported but even these cases do not appear to respond adequately to immunosuppression. The final diagnosis is obtained on necropsy.
Although we are ending on a sour note, I hope you have enjoyed this review of dysautonomia. Please let me know if you have any questions on this case, or any other neurology case.
I love helping you, help your patients with neurologic disease!