- Type Disease
Nervous System
- Name
Spinal Muscular Atrophy/motor neuron diseases
- Abbreviation
SMAx
- Description
The term spinal muscular atrophy is applied to most of the inherited motor neuron diseases in humans that affect mainly (although not exclusively) motor neurons. Motor neurons are the nerve cells that convey impulses to the muscles to produce movement. The syndromes vary between breeds (see below) but in general, degeneration of these neurons causes progressive weakness with difficulty in supporting weight, reduced reflexes, abnormal gait, and a loss of muscle mass (muscle atrophy).\n\nFor many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive.
- Diagnosis
Diagnosis is based on a thorough neurologic examination, the absence of abnormalities on routine diagnostic tests, and the progressive nature of these conditions. Specific diagnostic tests include muscle biopsy and electronic testing of nerve conduction potentials (an electromyogram) of affected muscles.
- Treatment
There is no treatment. These conditions are slowly or rapidly progressive, with the exception of German shepherd focal spinal muscular atrophy where the effects may be relatively mild.
- Veterinarian Information
The lower motor neuron signs with these disorders may be confused with canine protozoan radiculomyelitis. Electromyography typically shows spontaneous denervation potentials. Muscle atrophy is evident on muscle biopsy.
- Breeding Considerations
Affected dogs should not be bred. Breeding of parents and siblings (suspect carriers) should be avoided as well, so as not to perpetuate these serious and fortunately rare disorders. In family lines of Brittany spaniels where this disorder has occurred, dogs should not be bred until at least 3 years of age to ensure that any carriers are recognized.
- Known Breeds Affected
Brittany\nPointer (English pointer)\n
