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Inheritance of hypoadrenocorticism in Bearded Collies

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  • 1 Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616.
  • | 2 Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616.
  • | 3 Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616.
  • | 4 Institute of Molecular Biology, College of Arts and Sciences, University of Oregon, Eugene, OR 97403.
  • | 5 Institute of Molecular Biology, College of Arts and Sciences, University of Oregon, Eugene, OR 97403.
  • | 6 Department of Animal Science, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616.

Abstract

Objective—To assess heritability and mode of inheritance for hypoadrenocorticism in Bearded Collies.

Animals—635 Bearded Collies.

Procedure—Dogs were classified as affected by hypoadrenocorticism or unaffected. Phenotypic and pedigree data were analyzed. Heritability was estimated by use of Bayesian statistical methods. Regressive logistic models for complex segregation analyses were used to characterize mode of inheritance.

Results—Hypoadrenocorticism was diagnosed in 60 (9.4%) dogs. Heritability of hypoadrenocorticism was estimated to be 0.76 with both sexes affected with equal probability. Evaluation of the pedigrees did not support a Mendelian autosomal dominant mode of inheritance. Evidence from the complex segregation analysis for a single locus of large effect on hypoadrenocorticism was not convincing.

Conclusions and Clinical Relevance—Hypoadrenocorticism in Bearded Collies is highly heritable. Although a precise genetic mechanism responsible for inheritance of the disorder remains undetermined, breeding decisions must include consideration of the genetic likelihood of passing on this deleterious disorder to offspring of affected dams and sires. (Am J Vet Res 2002;63:643–647).