Myasthenia Gravis is a neurological disorder which can be inherited or acquired. The full description is lengthy but, in brief, it boils down to abnormal or failed transmission of messages from a nerve to the muscle, resulting in the affected muscle becoming weak, sometimes severely [Myasthenia Gravis explained].
In Sophie’s dog, Penny [Testimonials], the condition appears to have been diagnosed as congenital and has affected her gullet. The muscles of the oesophagus are often weak in dogs with Myasthenia Gravis, meaning that animals may have problems swallowing and often bring back food after eating. In severe cases the muscles involved with breathing can also be affected.
Severe weakness after only a few minutes of exercise, and this weakness might affect all four legs or only affect the back legs. Often preceded by a short stride stiff gait with muscle tremors. As soon as an affected animal rests they regain their strength and can be active for a brief period before exercise-induced weakness returns.
Other signs of Myasthenia Gravis in dogs are related to effects on the muscles in the throat and include regurgitation of food and water, excessive drooling, difficulty swallowing, laboured breathing and voice change. In the most severe form, the animal can be totally floppy and unable to support its weight or hold its head up. Muscle disease (myopathy) or nerve disease (neuropathy) can mimic signs of Myasthenia Gravis and should be considered in the diagnosis.
Dogs with congenital Myasthenia Gravis are born with too few acetylcholine receptors caused by a faulty immune-system. The main role of the immune system is to protect the body against infection or foreign invaders, and this is often done by the production of antibodies. In acquired Myasthenia Gravis, immune system produces antibodies (called anti-acetylcholine receptor antibody or AChR antibody) which attack and destroy the acetylcholine receptor.