NEUROMUSCULAR CASE OF THE MONTH DECEMBER 2010

Three autoimmune diseases in an 8 year old female-spayed
Labrador retriever mix

Contributed by Dr. Robert Lofton
University Animal Clinical
Lake Charles, LA


Clinical History
An 8-year-old female spayed Labrador retriever mix was presented for a 2 week history of lethargy. The patient had a history of cervical disc decompression several years previously and has since been on daily carprofen for osteoarthritis. Routine blood work consisting of a CBC, serum chemistry profile and bile acids indicated a mild regenerative anemia. Carprofen was discontinued and the patient switched to Tramadol for pain control.  One week following initial presentation, “coughing and vomiting” was described by the owner.



Physical Exam
With the exception of a slight increase in lung sounds, general physical examination was unremarkable. Cranial nerve examination revealed an absence of the menace reflex bilaterally and bilateral facial nerve paralysis. Drooling was excessive. Retinal examination was normal but the dog was minimally visual. The vomiting described by the owner was actually regurgitation

Diagnostic Testing
Thoracic radiographs A large megaesophagus was noted following a barium meal.
CBC HCT 30.2% (reference 37.0-55.0); HGB 11.5 g/dL (reference 12.0-18.0); MCHC 38.0 g/dL (reference 30.0-37.5)
Serum chemistry panel – Cholesterol >520 mg/dL (reference 110-320)
Thyroid testing – T4 <0.4 µg/dL (reference 1.0-4.0)
Acetylcholine receptor antibody titer – 1.21 nmol/l (reference <0.6)

Treatment and Clinical Outcome: 
Based on laboratory testing, the patient was diagnosed with hypothyroidism and acquired myasthenia gravis.  Over the next two weeks the patient was treated with levothyroxine sodium for hypothyroidism, enrofloxacin for mild aspiration pneumonia and pyridostigmine bromide syrup for myasthenia gravis.  The owners also were instructed to feed from an elevated position. During this time the patient improved considerably but continued to be minimally visual with an absence of the menace reflex. 

The patient was referred to Gulf Coast Animal Eye Clinic for evaluation by a veterinary ophthalmologist. Ophthalmologic examination confirmed the absence of ocular reflexes bilaterally with negative dazzle light reflex and negative hand menace reflex. Multifocal tapetal hyperreflectivity and vascular boxcarring consistent with Sudden Acquired Retinal Degeneration (SARDs) was evident bilaterally (see below, arrow highlights vascular boxcarring).

Thank you to Drs.  M.B Glaze and J. Swanson for supplying the digital image of SARDs

 

In conclusion, we suspect our patient  has 3 autoimmune diseases occurring concurrently; acquired myasthenia gravis, hypothyroidism and SARDs. The patient is currently doing very well on thyroid  supplementation, pyridostigmine bromide and feeding from an elevated position.

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