October 30, 2017

Heritability and complex segregation analysis of hypoadrenocorticism in the standard poodle

This study by T. R. Famula, J. M. Belanger, and A. M. Oberbauer discusses the prevalence of hypoadrenocorticism (Addison’s disease) in the standard poodle. Addison’s disease (AD) is an adrenal disease that affects important hormones used in metabolism. Hypoadrenocorticism is actually a rare disease in dogs, but has an uncharacteristically large presence in the poodle (standard) breed. This study questions the heritability of AD, the mode of inheritance of AD, and asks if there is an existence of a sex or color coat effect on the expression of AD in standard poodles. The scientists hypothesized that AD was a genetic disorder and that there is an existence of a sex and coat color effect on the development of AD. They predicted that if AD is a genetic disorder, then it would either be autosomal dominant or autosomal recessive Mendelian locus. They also predicted if there is a sex effect on the development of AD, then females are more likely to develop AD compared to males.

This study gathered data from 778 standard poodles with a recorded phenotype of hypoadrenocorticism. The standard poodles were split into male and female groups, divided by color, and then divided by normal and affected standard poodles.

The conclusion is that there is no existence of a sex or coat color effect on the development of AD. AD is fairly equally present across females and males. The results were able to eliminate the cause and mode being of autosomal dominant Mendelian locus. The results now led the researchers to believe the mode is through a recessive gene. Regarding coat color, there was no correlation between coat color and AD. There was no sign of AD in the apricot coat colored poodles, but that is negligible because there were only 12 standard poodles, making the sample size too small.

T. R. Famula, J. M. Belanger, A. M. Oberbauer, 2003. Journal of Small Animal Practice, 44:8-12.

Original Article: http://onlinelibrary.wiley.com/doi/10.1111/j.1748-5827.2003.tb00096.x/epdf

Reviewed by Hannah Cohen