Exercise-Induced Metabolic Myopathy in German hunting terrier (EIMM)
Exercise-induced metabolic myopathy (EIMM) is an inherited muscle disorder which affects the German hunting terrier dog breed. It belongs to a wider group of disorders, generally known as metabolic myopathies, which are caused by specific enzymatic defects as result of genetic mutation. Although metabolic myopathies are heterogeneous disorders, they are characterized by common abnormalities of muscle energy metabolism. Exercise-induced metabolic myopathy (EIMM) in dogs has until now been identified only in German hunting terriers.
Characteristics and Symptoms
EIMM symptoms include generalized weakness, exercise-induced intolerance, and severe diffuse muscle pain. Owners report that EIMM affected German hunting terriers cannot be used for hunting since they collapse and develop tetraparesis and tetraplegia 30 to 120 minutes after the start of the exercise. During the collapse episodes, urine of the affected dogs presents brownish discoloration. Affected dogs do not present cardiac or pulmonary abnormalities, and no neurological abnormalities have been noticed either. Chemical examination of blood samples reveals high plasma creatine kinase activity, as well as plasma alanine transaminase activities. Muscle biopsy indicated mild to moderate necrotizing myopathy and mitochondrial abnormalities.
Exercise-induced metabolic myopathy in German hunting terrier is caused by a nonsense mutation of ACADVLD gene. The disorder is inherited as an autosomal recessive disorder. Healthy parents of an affected dog are obligate heterozygotes and therefore carry one mutant allele. Heterozygotes are carriers and show no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.
Lepori, V. et al (2018) A Nonsense Variant in the ACADVL Gene in German Hunting Terriers with Exercise Induced Metabolic Myopathy. G3 (Bethesda). 2018 May 4;8(5):1545-1554. doi: 10.1534/g3.118.200084.