Mitochondrial Fission Encephalopathy (MFE) is a genetic disorder affecting the Bulllmastiff breed and characterised by ataxia, hypermetria, conscious proprioceptive deficits, behavioural abnormalities, and a visual deficit.
Symptoms start early in life when the pups are 6-16 weeks old and include visual impairment unsteady gait, uncoordinated movement, stiffness in the muscles of the back legs, bizarre behavioural changes and eventually puppies become unable to stand, and euthanasia is usually carried out as a result of continued deterioration and unresponsiveness to treatment.