Myasthenia Gravis (Acquired)
Myasthenia gravis is a disease resulting in muscle weakness. There are two forms of this disease: a congenital form due to a developmental abnormality resulting in a deficiency or abnormality of acetylcholine receptors on the postsynaptic membrane of the neuromuscular junction, and an acquired form that is associated with antibodies being produced against the acetylcholine receptor.
In other dogs, only evidence of focal muscle involvement can occur with myasthenia gravis. Megaesophagus may be the only clinical manifestation of the disease in many dogs.
In other dogs, only evidence of focal muscle involvement can occur with myasthenia gravis. Megaesophagus may be the only clinical manifestation of the disease in many dogs.
Age of Onset: 6 years (range from 8 months to 14 years)
Sex Predisposition: Any sex of animal can be affected. In some reports spayed and neutered dogs were at higher risk.
Clinical Course:
There are three clinical forms recognized in dogs: focal (megaesophagus), generalized, and fulminating
Clinical signs worsen with exercise, and generalized weakness typically recovers with 60-90 minutes of rest.
There are three clinical forms recognized in dogs: focal (megaesophagus), generalized, and fulminating
Clinical signs worsen with exercise, and generalized weakness typically recovers with 60-90 minutes of rest.
Clinical Signs:
Posture and Appearance
Kyphotic posture (pelvic limbs help more cranial)
Flexed neck posture
Movement
Exercise-intolerance
Progressive shortening of inter-step distance as they continue to run/walk
Collapse with exercise
Cranial Nerves
Progressive weakness of facial muscles (“droopy” or tragic facial expression)
Special Functions (e.g. respiration; urination)
Regurgitation
Dyspnea
Dysphonia
Ptyalism
Other
Signs of aspiration pneumonia
Posture and Appearance
Kyphotic posture (pelvic limbs help more cranial)
Flexed neck posture
Movement
Exercise-intolerance
Progressive shortening of inter-step distance as they continue to run/walk
Collapse with exercise
Cranial Nerves
Progressive weakness of facial muscles (“droopy” or tragic facial expression)
Special Functions (e.g. respiration; urination)
Regurgitation
Dyspnea
Dysphonia
Ptyalism
Other
Signs of aspiration pneumonia
Diffuse to focal neuromuscular
Unknown
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