Genetic aspects of Labrador Retriever myopathy.

Area of Science:

• Veterinary Genetics
• Canine Muscular Diseases
• Animal Models of Human Disease

Background:

• Labrador Retriever myopathy (LRM) is an increasingly prevalent muscular disorder in dogs.
• Understanding the genetic basis of LRM is crucial for developing effective management and breeding strategies.

Purpose of the Study:

• To determine the mode of inheritance for Labrador Retriever myopathy (LRM) using segregation analyses.
• To investigate potential genetic and environmental factors influencing both clinical and subclinical forms of LRM.

Main Methods:

• Prospective study involving neurological examinations, electromyography, and histopathology on 58 closely related Labrador Retrievers.
• Segregation analyses were performed on an extended pedigree of 164 related dogs using three genetic models.
• Phenotypic data were categorized into clinically normal/abnormal and histopathologically normal/abnormal datasets.

Main Results:

• Clinical signs of LRM, including exercise intolerance, were observed in 7 dogs.
• Histopathological findings consistent with LRM were present in all clinically affected dogs and 41 clinically normal dogs.
• Segregation analyses supported an autosomal recessive major gene mode of inheritance for the clinical form of LRM.

Conclusions:

• The clinical form of Labrador Retriever myopathy is primarily controlled by an autosomal recessive major gene.
• An additional gene or environmental factor likely contributes to the expression of the subclinical form of LRM.
• LRM shares similarities with human limb-girdle muscular dystrophy, suggesting its potential as a valuable animal model.