NEUROMUSCULAR CASE OF THE MONTH – SEPTEMBER 2009

Effective treatment regimen for megaesophagus secondary to focal myasthenia gravis
Contributed by Dr. John F. Wilson
Wilson Veterinary Hospital
Washington, MI

Clinical History
A 10 year old female spayed Canaan dog (Figure 1) presented for coughing and frequent vomiting of 48 hour duration. Past history included panniculitis that was treated with prednisone four years earlier. Recently, the owner had reported stumbling while walking.

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Figure 1. Owner noted weakness in the agility ring

Physical and Neurological Examination
On presentation the patient appeared depressed with increased lung sounds bilaterally. The dog attempted to eat and drink, but immediately regurgitated. No other specific abnormalities were noted on physical or neurological examination.

Diagnostic Testing
CBC and serum chemistry analysis were within normal limits.
A T4 level from 6 months prior was also within normal limits.
Acetylcholine receptor antibody titer – 7.74 nmol/l (canine reference <0.6nmol/l)
Thoracic radiographs – Esophageal dilation (megaesophagus) and aspiration pneumonia

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Figure 2. Large air-filled esophagus (megaesophagus) evident on thoracic radiographs. Dorsal  and  ventral borders of the esophagus are highlighted with arrows.


Diagnosis and Outcome

The positive acetylcholine receptor antibody titer was diagnostic of acquired myasthenia gravis. Treatment regimen included pyridostigmine bromide (15mg PO three times daily) and prednisone (2.5mg every other day). A PEG tube was placed initially for nutritional support, fluid therapy and administering medications as the patient had lost 30% of the body weight within 2 weeks of diagnosis. Five months post-diagnosis, the dog ran in a national agility competition with the PEG tube in place. Using the “Bailey Chair” (go to May 2005 Case of the Month, see Figure 3), an “elevated bowl” technique was established for feeding the dog from a vertical position.


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Figure 3. Feeding from the "Bailey Chair"

The feeding regimen included a mixture of I/D and oatmeal four times daily, keeping the dog in a vertical position for 20 minutes after each feeding. According to the owner, using this specific feeding chair made a dramatic difference in the clinical outcome, and allowed for removal of the PEG tube. The dog is now thriving and still competing in agility (See Figure 4).

Note: A follow up acetylcholine receptor antibody titer in January 2010 showed the antibody titer still positive at 1.33nmol/l.

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Figure 4. Competing in Agility

 

 

 

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