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NEUROMUSCULAR CASE OF THE MONTH - MARCH 2001
Chronic progressive weight loss and exercise intolerance in a
12 year old male Siberian Husky
Contributed by Dr. Michael Podell
The Ohio State University
Columbus, OH 43210-1089
Clinical History
The dog presented for an approximately 2 month history of weakness beginning in the rear limbs and then progressing to involve
the front limbs. The owner reported the dog would occasionally stumble forward and fall. The dog had been fed a homemade diet
of rice, turkey, and one raw fish daily for approximately 5 years. Other past medical problems included a cervical vertebral
injury and immune-mediated hemolytic anemia.
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Figure 1.
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Physical Examination
Symmetrical atrophy of the muscles of all four limbs was present. The dog appeared painful on manipulation of the metatarsal-phalangeal joints, but interpretation
was difficult as he resisted virtually all examination. The neurological examination revealed tetraparesis that worsened wtih exercise, decreased strength on hemistanding,
and a decreased flexor reflex in all four limbs. A neuromuscular disorder was suspected.
Diagnostic Testing
No specific abnormalities found on CBC, serum chemistry profile, urinalysis, or evaluation of thyroid hormone.
Limb radiographs - Mild arthritic changes but could not explain the severity of the clinical signs.
Electrophysiology - Fibrillation potentials were found by electromyography in several distal muscles including the cranial tibial, gastrocnemius and flexor carpi
ulnaris muscles. The motor nerve conduction velocity of the left sciatic nerve was slowed at 34.2 m/sec (normal 50 m/sec or greater), with a decreased amplitude
of the motor unit action potential and a decreased F-ratio. The assessment was a severe distal polyneuropathy with primary axonal degeneration.
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Muscle Biopsy: Pathological changes within the muscle biopsy (not shown) were consistent with denervation. A fixed, plastic embedded biopsy from the peroneal
nerve showed a moderate depletion of large myelinated nerve fibers, axonal degeneration, and numerous small thinly myelinated nerve fibers. |
Figure 2. |
Treatments and Clinical Outcome
A polyneuropathy associated with a nutritional deficiency, possibly associated with a B vitamin deficiency, was suspected. The dog was given vitamin B complex injections
while in the hospital. An adult formula vitamin B complex (B-1000 complex, 1 tablet BID PO) was continued at home. A recommendation was made to feed a commercial diet
that is more nutritionally balanced. If a home cooked diet was continued, it was suggested to cook the fish. The owner reported that at 3 months following the initial
visit the dog was doing much better and could walk 6 blocks (versus 1 block) before tiring, was more energetic, and was getting around the house and yard better. In
a follow-up at 9 months continual improvement was reported with the dog more active and gaining muscle mass. Peripheral neuropathy associated with deficiency of vitamin
B1 is the major feature of "dry beriberi" described in humans (Windebank 1993). This neuropathy is associated with "burning feet syndrome" and a
distal symmetric muscle weakness and atrophy. The disease developed in humans who used rice as a dietary staple. Thiaminase, present in raw fish, may have further added
to the vitamin depletion.
Windebank AJ. Polyneuropathy due to nutritional deficiency and alcoholism. In: Peripheral Neuropathy 3rd Edition. Dyck PJ, Thomas PK, Griffin JW, Low PA, Poduslo
JF (eds). W.B. Saunders Co, 1993, Philadelphia, 1310-1321.
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