BackgroundAnalysis of 88,635 dogs seen at the University of California, Davis Veterinary Medical Teaching Hospital from 1995 to 2010 identified ten inherited conditions having greater prevalence within the purebred dog population as compared to the mixed-breed dog population: aortic stenosis, atopy/allergic dermatitis, gastric dilatation volvulus (GDV), early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, hypothyroidism, intervertebral disk disease (IVDD), and hepatic portosystemic shunt. The objective of the present study was to ascertain if disorders with higher prevalence in purebreds were restricted to particular breed group classifications within the purebred population, specifically the American Kennel Club breed grouping or groups with genomic similarities based upon allele sharing. For each disorder, healthy controls seen at the hospital during that same time period were matched for age, weight, and sex to each affected dog to determine risk of disease presentation in the purebred group as compared to that of the mixed-breed population. To enhance reliability of the analyses, sampling of matched healthy to affected dogs was repeated 50 times. For each comparison, the purebred subgroups to mixed-breed odds ratio was determined as was the mean P value used to test this ratio.ResultsFor aortic stenosis, GDV, early onset cataracts, dilated cardiomyopathy, elbow dysplasia, epilepsy, and portosystemic shunt, most purebred groups were not statistically distinct from the mixed-breed population with higher prevalence in purebreds restricted to distinct subsets of purebred dogs. The conditions of atopy/allergic dermatitis, hypothyroidism, and IVDD were more pervasive across the purebred population with many groups having higher prevalence than the mixed-breed population. The prevalence of IVDD in purebred terrier groups was statistically lower than that observed for mixed-breed dogs.ConclusionsThe results offer an assessment of the distribution of inherited disorders within purebred dogs and illustrate how mixed-breed and subpopulations of purebred dogs do not differ statistically in prevalence for certain disorders. Some disorders appear linked to common ancestors providing insight into disease allele origin whereas others may be due to selection for common structural morphology. Knowledge of the origin of a condition may aid in reducing its prevalence in the dog population as a whole.Electronic supplementary materialThe online version of this article (doi:10.1186/s40575-015-0021-x) contains supplementary material, which is available to authorized users.

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Animals bred in pastoral systems are often part of multiple-sire groups, introducing uncertainty into pedigrees. Genetic evaluation of sires and dams in such instances is complicated by the uncertainty of parenthood. This article defines a simple and rapid algorithm to compute the inverse of a numerator relationship matrix under uncertain parenthood. The algorithm can accommodate inbreeding and uncertainty of parenthood on both paternal and maternal sides of the pedigree.

Female mice carrying a regulatable growth hormone transgene (oMt1a-oGH) are subfertile when the transgene is actively expressed. This study was designed to characterize subfertility caused by increased concentrations of growth hormone. In particular, this study aimed to: (i) determine the effects of transgene activation and inactivation on mating, conception, maintenance of pregnancy, ovulation rate, litter characteristics and embryonic survival at day 17 of pregnancy, (ii) characterize oestrous cyclicity in transgenic versus wild-type female mice, and (iii) correlate corticosterone concentrations with transgene expression and reproductive performance. Transgenic and wild-type female mice were allocated randomly to one of four treatment groups at weaning: (i) transgenic female mice that always express the transgene, (ii) transgenic female mice that never express the transgene, (iii) transgenic female mice that express the transgene for up to 8 weeks of age and (iv) non-transgenic wild-type female mice receiving the transgene stimulus until 8 weeks of age. Activation followed by inactivation of the transgene resulted in an increased incidence of remating, resulting in an extended interval to establish pregnancy in comparison with all other treatment groups. Transgenic mice that always expressed the transgene and those that expressed the transgene for up to 8 weeks of age had lower pregnancy rates and higher ovulation rates compared with mice from other treatment groups. Both embryonic survival and the duration of the oestrous cycle did not differ among treatment groups. Active expression of the transgene resulted in an increase in the plasma concentration of corticosterone, which was associated with reduced fertility. These data indicate that the presence of a high growth hormone concentration impedes the establishment and maintenance of pregnancy. Increased plasma corticosterone concentrations may interfere with implantation as well as potentiate leptin resistance, which has been reported previously in studies with these mice.

BackgroundAddison's disease, also known as hypoadrenocorticism, has been reported in many individual dogs, although some breeds exhibit a greater incidence than the population as a whole. Addison's is presumed to be an autoimmune mediated hereditary defect but the mode of inheritance remains unclear. In particular, the heritability and mode of inheritance have not been defined for the Portuguese Water Dog although Addison's is known to be prevalent in the breed.ResultsThe analyses present clear evidence that establishes Addison's disease as an inherited disorder in the Portuguese Water Dog with an estimate of heritability of 0.49 (± 0.16); there were no differences in risk for disease across sexes (p > 0.49). Further, the complex segregation analysis provides suggestive evidence that Addison's disease in the Portuguese Water Dog is inherited under the control of a single, autosomal recessive locus.ConclusionThe high heritability and mode of inheritance of Addison's disease in the Portuguese Water Dog should enable the detection of segregating markers in a genome-wide scan and the identification of a locus linked to Addison's. Though the confirmation of Addison's disease as an autosomal recessive disorder must wait until the gene is identified, breeders of these dogs may wish to keep the present findings in mind as they plan their breeding programs to select against producing affected dogs.