Feline myasthenia gravis

Question 1

How frequent is myasthenia gravis in cats

Answer 1

Acquired myasthenia gravis seems more frequent than previously thought

Question 2

What is the pathomechanism for feline acquired myasthenia gravis

Answer 2

Feline acquired myasthenia gravis is an immune disorder causing disruption of neuromuscular transmission through the production of autoantibodies targeting post-synaptic nicotinic acetylcholine receptors
- the resulting clinical presentation is skeletal muscle weakness and fatigability

Question 3

What is the cause of feline congenital myasthenia gravis

Answer 3

A missense mutation affecting the COLQ gene has been identified in Devon Rex and Sphynx cats
- the mutation is transmitted in an autosomal recessive manner

Question 4

What are the three clinical presentations of feline acquired myasthenia gravis

Answer 4

The focal form
- involves weakness of any or all of the facial, oesophageal, pharyngeal and laryngeal skeletal muscles
- clinical signs:
- dysphagia
- hypersalivation
- regurgitation
- decreased palpebral reflex and menace response
- dysphonia

The generalized form
- involves appendicular muscle weakness and cervical ventroflexion, with or without the clinical signs of the focal form

The fulminant form
- describes a rapid and severe onset of the generalized form
- frequently accompanied by respiratory distress from exhaustion of the respiratory skeletal muscles

Question 5

What is the most common presentation for myasthenia gravis in cats

Answer 5

The most common presentation is the generalized form (70-90%) followed by the focal and fulminant form

Question 7

How can you reach a definitive diagnosis of feline acquired myasthenia gravis

Answer 7

Measurement of serum anti-acetylcholine receptor antibody concentration provides a definitive diagnosis

The edrophonium chloride challenge test and eclectrodiagnostic tests may support the diagnosis but are not specific