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A case of Floppy Rabbit Syndrome (FRS)

Rocket

This male neutered rabbit is suffering from 'Floppy Rabbit Syndrome' or FRS. It is an acute condition that is characterised by a sudden inability to hop or move around normally. This rabbit was found is showing the typical clinical picture. The findings of his neurological examination were.

  • He was responsive and appeared to be mentally normal
  • He was eating, drinking, urinating and defaecating normally, which suggested that autonomic function was unaffected.
  • His movement was uncoordinated
  • There was tetraparesis (weakness off all four legs) 
  • His tail was was not affected.
  • The anal sphincter tone was not affected. 
  • There was no apparent sensory loss. The tail would twitch in response to stimulation e.g. pinching the skin or pricking with a needle.
  • Postural and spinal reflexes wear hard to assess but appeared to be subdued.
  • No cranial nerve deficits were apparent.

The rabbit recovered with supportive care over a period of 3-4 days. He was give meloxicam on the basis that there might be some muscular pain from lying in an abnormal condition. His food and water were kept close to him and his bedding was changed as soon as he urinated or defaecated because he couldn't move away from urine or faeces. 

The neurological findings and clinical history of this rabbit are typical of FRS. Although it is tempting to think at the outset that the outlook for affected rabbits is hopeless and that they are suffering, it is worth persevering as many cases will recover with palliative care. Many cases recover quickly. Others can take a week or more. In severe cases, all the muscles of the neck, back and legs are affected to the rabbit so the rabbit cannot move or lift its head. In the most severe cases, the respiratory muscles are affected and the rabbit can die from respiratory failure. Euthanasia should be considered for rabbits that are unable to move and are not eating or breathing properly. 
Some rabbits only have a single episode. Others have repeated episodes, often following a period of stress. The condition does not appear to be linked with with age, gender or breed but this has not been confirmed. Other diseases can cause similar signs and diagnostic tests, such as serology for Encephalitozoon cuniculi, CT/MRI scanning, cerebrospinal fluid analysis and electromyelography are helpful although they can be expensive. 

The neurological findings of FRS suggest a lower motor neuron condition and polyradiculoneuritis (inflammation of the nerve roots) is suspected. The cause of FRS has not been determined but the clinical features are similar to Coonhound paralysisis dogs and also has similarities to Guillan-Barre syndrome in people. It is believed to be an autoimmune disorder. Confirmation of the diagnosis is difficult and requires specialised blood tests and post-mortem investigations that are unavailable at this time.