Pyruvate dehydrogenase complex deficiency (PDCD) is one of the most common neurodegenerative disorders associated with abnormal mitochondrial metabolism. The citric acid cycle is a major biochemical process that derives energy from carbohydrates. Malfunction of this cycle deprives the body of energy. Severe enzyme deficiencies may lead to congenital brain malformation because of a lack of energy during neural development. An abnormal lactate buildup results in severe lethargy, poor feeding, abnormally rapid breathing, especially during times of illness, or exertion. Progressive neurological symptoms usually start early in life, but may be evident at birth. These signs may include developmental delay, intermittent lack of muscle coordination (ataxia), poor muscle tone, abnormal eye movements, or seizures. The disease is also characterised by exercise intolerance and post-exercise collapse.
The mode of inheritance is autosomal recessive. A dog must therefore have two copies of the PDP1 deficiency form of the gene to show symptoms. Dogs with one copy of the PDP1 deficiency form of the gene and one copy of the normal form do not show symptoms but can pass the PDP1 deficiency form of the gene onto their puppies. The disease has been reported in Old English sheepdogs, Clumber spaniels and Sussex spaniels.
TREATMENT
Treatment of affected dogs with a high-fat, ketogenic, diet has been suggested. Since the underlying progressive neurological damage is irreversible, the prognosis is usually poor.