Myelin Deficiency in Cats

Hypomyelination in Cats

A fatty substance that covers the axons (the portions of the nerve cells that transfer impulses to other cells of the body), myelin serves an important function for the nerve cells: as an insulator, protecting the nerve from outside influences, and as an aid for forwarding the process of cellular transmission of nervous system actions. Therefore, hypomyelination, or an insufficient production of myelin in the body, can be devastating for the central nervous system (CNS). It can even cause tremors, which are most apparent when the cat is active.

CNS hypomyelination has a higher rate of diagnosis in the Siamese breed.


Central nervous system:

  • Clinical signs appear within days of birth
  • Body tremors that worsen with activity and decline during rest
  • Symptoms generally improve by one year of age

Peripheral Nervous System:

  • Clinical signs appear at 5–7 weeks of age
  • Weakness
  • Incoordination of the rear limbs (ataxia)
  • Muscle wasting
  • Hyporeflexia (below normal or absent reflexes)
  • Symptoms do not resolve with age


  • Cause is unknown, but viral or toxic sources are considered, especially since symptoms often resolve
  • Peripheral nervous system disease origin is undetermined, but is suspected to be genetically based


Your veterinarian will perform a thorough physical exam on your cat, taking into account the background history of symptoms and your cat’s genetic background. Standard tests include a blood profile, including a chemical blood profile, a complete blood count, and a urinalysis.

Diagnosis is based on the clinical signs that your cat is presenting, but for a conclusive diagnosis, your veterinarian will take a sample/biopsy of the nerve to analyze for sufficient myelin at the axon of the nerve. Your doctor may also choose to perform a brain biopsy. Other techniques include electromyography, which measures the electrical activity and potential of the muscle cells. In this case, the finding is usually normal to mild spontaneous activity. Motor nerve conduction velocity can be used to assess the ability of the motor and sensory nerves to conduct electricity. With hypomyelination, there is usually slowed conduction or only a small amount of potential.


A bundle of fibers that are used in the process of sending impulses through the body


An in-depth examination of the properties of urine; used to determine the presence or absence of illness


A type of covering over certain nerve cells; may be found in areas of the spinal cord or on the brain’s white matter


The process of removing tissue to examine it, usually for medical reasons.


The part of the neuron that is extended out from the cell and works to conduct electrical impulses.


A medical condition in which an animal is unable to control the movements of their muscles; may result in collapse or stumbling.

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