Congenital myoclonus

From Cow

Inherited congenital myoclonus (neuraxial edema) is a rare autosomal recessive genetic disease of Hereford and Holstein[1] calves characterised by neurological signs[2].

Newborn calves are often bright, alert and responsive but sensory stimuli like auditory or tactile impulses induced myoclonic jerking of the whole body, including intermittent extensor spasm, hyperaesthesia and nystagmus[3].

Binding studies have shown that the myoclonus is associated with a deficiency of inhibitory glycine receptors[4] in brain stem and spinal cord in affected calves[5].

Diagnosis is based on histopathology, where vacuolation of the central nervous system is characteristic of this disease. Either the white or grey matter or both parts of the brain may be affected. Hypomyelinogenesis is also a feature of this disease[6].

A differential diagnosis would include other congenital myopathies such as muscular dystonia, arthrogryposis multiplex, neuropathic hydrocephalus, progressive degenerative myeloencephalopathy and spinal muscular atrophy.

As this is an hereditary disease, euthanasia is usually required. Most calves do not survive due to the severity of the condition.

References

  1. Schulze U et al (2006) Case report: congenital myoclonus in a German Holstein calf. Dtsch Tierarztl Wochenschr 113(5):203-206
  2. Harper PA et al (1986) Inherited congenital myoclonus of polled Hereford calves (so-called neuraxial oedema): a clinical, pathological and biochemical study. Vet Rec 119(3):59-62
  3. Healy PJ et al (1986) Diagnosis of neuraxial oedema in calves. Aust Vet J 63(3):95-96
  4. Gundlach AL (1990) Disorder of the inhibitory glycine receptor: inherited myoclonus in Poll Hereford calves. FASEB J 4(10):2761-2766
  5. Pierce KD et al (2001) A nonsense mutation in the alpha1 subunit of the inhibitory glycine receptor associated with bovine myoclonus. Mol Cell Neurosci 17(2):354-363
  6. Duffell SJ (1986) Neuraxial oedema of Hereford calves with and without hypomyelinogenesis. Vet Rec 118(4):95-98