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Unsaturated omega-3 fatty acids, especially docosahexaenoic acid (DHA), when fed to dogs improves cognitive and neurological development. Supplementation with omega-3 fatty acids such as DHA and eicosapentaenoic acid (EPA) has also been associated with lipid peroxidation, which in turn has been implicated in reduced body weight and altered bone formation. To assess the impact of omega-3 fatty acid supplementation on skeletal growth, diets containing three levels of DHA and EPA (0.01 and 0.01%, 0.14 and 0.12%, and 0.21 and 0.18%, respectively) were fed to bitches during gestation and lactation with puppies also supplemented through weaning. Thus, the subjects studied were the puppies supplemented with DHA and EPA through gestation and early postnatal life. The hip joint conformation of the puppies (n = 676) was recorded at adulthood using two radiographic, non-invasive evaluations. In this population, females had higher hip distraction indices (DI) than males. Males from the lower two levels of DHA and EPA supplementation had significantly smaller hip DI than all females and males from the highest DHA and EPA supplementation. In contrast, there were no diet effects on anatomical indicators of hip joint conformation and no visible arthritic changes. These data suggest that dietary supplementation of DHA and EPA during gestation and the perinatal period to weaning does not adversely influence hip joint formation of dogs.

Canine hip dysplasia (CHD) and elbow dysplasia (ED) impact the health and welfare of all dogs. The first formally organized assessment scheme to improve canine health centered on reducing the prevalence of these orthopedic disorders. Phenotypic screening of joint conformation remains the currently available strategy for breeders to make selection decisions. The present study evaluated the efficacy of employing phenotypic selection on breed improvement of hips and elbows using the Orthopedic Foundation for Animals complete database spanning the 1970-2015 time period. Sixty breeds having more than 1000 unique hip evaluations and 500 elbow evaluations (1,056,852 and 275,129 hip and elbow records, respectively) were interrogated to derive phenotypic improvement, sex and age at time of assessment effects, correlation between the two joints, heritability estimates, estimated breeding values (EBV), and effectiveness of maternal/paternal selection. The data demonstrated that there has been overall improvement in hip and elbow conformation with a reduction in EBV for disease liability, although the breeds differed in the magnitude of the response to selection. Heritabilities also differed substantially across the breeds as did the correlation of the joints; in the absence of a universal association of these differences with breed size, popularity, or participation in screening, it appears that the breeds themselves vary in genetic control. There was subtle, though again breed specific, impact of sex and older ages on CHD and ED. There was greater paternal impact on a reduction of CHD. In the absence of direct genetic tests for either of these two diseases, phenotypic selection has proven to be effective. Furthermore, the data underscore that selection schemes must be breed specific and that it is likely the genetic profiles will be unique across the breeds for these two conditions. Despite the advances achieved with phenotypic selection, incorporation of EBVs into selection schemes should accelerate advances in hip and elbow improvement.

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.

OBJECTIVE: This study was undertaken to evaluate plasma leptin concentration in the regulatable ovine metallothionein-ovine growth hormone (oMT1a-oGH) transgenic (TG) mouse model of obesity. RESEARCH METHODS AND PROCEDURES: Transgene stimulus (zinc) was provided at 21 days of age to male and female wild-type (WT) and TG mice. Plasma leptin concentrations were measured by radioimmunoassay at 42, 63, 84, and 105 days of age and from inactivated TG mice at 84 and 105 days. RESULTS: WT and TG mice did not differ significantly in plasma leptin concentration at any of the ages examined (42, 63, 84, and 105 days), although females showed consistently higher plasma leptin concentrations than males regardless of genotype throughout the duration of the study. Male and female TG mice in which the transgene was inactivated at 63 days had a 1.5-fold to 3.5-fold increase in plasma leptin concentration over WT mice and continuously activated TG mice at 84 and 105 days of age. The elevated plasma leptin concentration seen in the inactivated TG mice at 84 and 105 days of age reflects the >300% increase in white adipose tissue seen in this model and correlated with all adipose depot weights and overall body lipid at these later ages. When plasma leptin was expressed per gram of total body fat, the leptin adjusted for body lipid was significantly higher in WT mice than either continuously activated TG or activated and then inactivated TG groups. DISCUSSION: The inactivated TG mice in this study had higher plasma leptin levels with increasing total body adiposity, but the relative proportion of circulating leptin, on a total body lipid basis, was reduced when compared with the WT mice. This reduction was also observed in activated TG mice at the older ages. Although the absolute levels of circulating leptin were elevated in the inactivated TG animals, the amount of leptin produced per gram of fat was lowered. With the inactivation of the transgene, the leptin remained depressed after the removal of the elevated growth hormone. This represents a potential explanation for the ensuing hypertrophy of the fat depots and the abnormal phenotypic response of inactivated TG mice to elevated plasma leptin concentrations resulting in the development of obesity.