Neuromyotonia refers to a combination of involuntary twitching of muscles (myokymia), muscle contraction, muscle stiffness or cramps and impaired muscle relaxation. It results from hyperexcitability of terminal nerve branches rather than a primary muscle disorder. The condition has been reported both in dogs and cats but is most well described in Jack Russell terrier. Cases of neuromyotonia have been also reported in Yorkshire Terriers, Border Collies, a Cocker Spaniel and mixed-breed dogs.2 In human patients acquired neuromyotonia is known as Isaacs' syndrome. Acquired neuromyotonia is increasingly recognized as an autoimmune disorder.

In all affected dogs, the excessive muscular contraction resulted in collapse. The dogs were fully conscious during the collapsing episodes which were usually triggered by stress, excitement or exercise and lasted from several minutes to several hours. Some dogs rubbed their faces intensely.


  1. Canine and Feline Epilepsy: Diagnosis and Management. Luisa de Risio, Simon Platt
  2. Practical Guide to Canine and Feline Neurology. Curtis W. Dewey, Ronaldo C. da Costa
  3. Paraneoplastic disorders in thymoma patients

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