Spinal muscular atrophy
Spinal muscular atrophy is a neurodegenerative disease characterized by severe loss of motor neurons. Degeneration and loss of motor neurons cause progressive weakness and neurogenic muscular atrophy. The disease is caused by a mutation in a gene which produces 3-ketodihydrosphingosine (KDS) reductase activity, which plays an important role in the biosynthesis of glycosphingolipids. Loss of this enzyme activity results in neuronal degeneration and progressive degenerative neuronal atrophy.
Clinically affected calves, especially heifers, present with hindleg weakness and reluctance to stand from 2 weeks of age. Severe muscular atrophy is evident on palpation of hindlimbs. Most calves tend to die within 2 weeks of birth.
Diagnosis is based on presenting clinical signs augmented with tissue samples of hindlimb muscles which show motor neuron swelling, chromatolysis and loss of neurons in the ventral horn, axonal swelling in the spinal cord, and accumulation of neurofilaments in affected neurons.
A differential diagnosis would include other congenital neurological diseases such as progressive degenerative myeloencephalopathy, arthrogryposis multiplex, neuropathic hydrocephalus. Infectious causes would include Histophilus somni and BSE.
There is no treatment for affected calves which invariably die.
- Krebs S et al (2007) A missense mutation in the 3-ketodihydrosphingosine reductase FVT1 as candidate causal mutation for bovine spinal muscular atrophy. Proc Natl Acad Sci U S A 104(16):6746-6751
- Krebs S et al (2006) Fine-mapping and candidate gene analysis of bovine spinal muscular atrophy. Mamm Genome 17(1):67-76
- el-Hamidi M et al (1989) Spinal muscular atrophy in Brown Swiss calves. Zentralbl Veterinarmed A 36(10):731-8