Clinical features and heritability of hypoadrenocorticism in Nova Scotia Duck Tolling Retrievers: 25 cases (1994-2006).
OBJECTIVE
To evaluate the clinical features and heritability of naturally occurring hypoadrenocorticism in Nova Scotia Duck Tolling Retrievers (NSDTRs).


METHODS
Retrospective case series.


METHODS
25 NSDTRs with hypoadrenocorticism.


METHODS
Questionnaires completed by owners of NSDTRs with hypoadrenocorticism and medical records from veterinarians were reviewed for information regarding diagnosis, age at diagnosis, concurrent diseases, age at death, and cause of death. Pedigrees were analyzed for heritability and mode of inheritance of hypoadrenocorticism (including complex segregation analysis of pedigrees of 1,515 dogs).


RESULTS
On the basis of results of ACTH stimulation testing, hypoadrenocorticism was diagnosed in 16 female and 9 male NSDTRs (including 6 full siblings). Median age at diagnosis was 2.6 years; the diagnosis was made prior to 2 years of age in 11 dogs. Seventeen dogs had hyponatremia, hyperkalemia, or both, and serum electrolyte concentrations were within reference ranges for 8 dogs at the time of diagnosis. Median survival time after diagnosis for 4 dogs that died or were euthanized as a result of medical causes was 1.6 years. Heritability was calculated at 0.98 with no sex effect, and complex segregation analysis fit a major gene model with an autosomal recessive mode of inheritance.


CONCLUSIONS
In NSDTRs, hypoadrenocorticism was diagnosed at an earlier age, compared with published reports of age at diagnosis among the general dog population. Among the study dogs, 32% had no serum electrolyte abnormalities at the time of diagnosis, and the disease appeared to have an autosomal recessive mode of inheritance in the breed.
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Angela M
AM
Hughes
Richard W
RW
Nelson
Thomas R
TR
Famula
Danika L
DL
Bannasch
D000311:Adrenal Glands / Q000473:pathology*; D000309:Adrenal Insufficiency / Q000453:epidemiology / Q000235:genetics / Q000473:pathology / Q000662:veterinary*; D000324:Adrenocorticotropic Hormone; D000367:Age Factors; D000818:Animals; D004198:Disease Susceptibility / Q000662:veterinary; D004283:Dog Diseases / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology*; D004285:Dogs; D005260:Female; D020022:Genetic Predisposition to Disease; D008297:Male; D009674:Nova Scotia / Q000453:epidemiology; D010375:Pedigree; D012189:Retrospective Studies; D011795:Surveys and Questionnaires
D000324:Adrenocorticotropic Hormone