Randall H. Rieger

Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas

OBJECTIVE To investigate associations between age at gonadectomy and estimated risk or age at diagnosis of neoplastic and behavioral disorders in Vizslas. DESIGN Retrospective cohort study. ANIMALS 2,505 Vizslas born between 1992 and 2008. PROCEDURES Data on demographics, gonadectomy status, and age at diagnosis of disease or disorder were obtained with an anonymous online survey and analyzed. RESULTS Dogs gonadectomized at ≤ 6 months, between 7 and 12 months, or at > 12 months of age had significantly increased odds of developing mast cell cancer, lymphoma, all other cancers, all cancers combined, and fear of storms, compared with the odds for sexually intact dogs. Females gonadectomized at ≤ 12 months of age and males and females gonadectomized at > 12 months of age had significantly increased odds of developing hemangiosarcoma, compared with the odds for sexually intact dogs. Dogs gonadectomized at ≤ 6 months of age had significantly increased odds of developing a behavioral disorder. The younger the age at gonadectomy, the earlier the mean age at diagnosis of mast cell cancer, cancers other than mast cell, hemangiosarcoma, lymphoma, all cancers combined, a behavioral disorder, or fear of storms. CONCLUSIONS AND CLINICAL RELEVANCE Additional studies are needed on the biological effects of removing gonadal hormones and on methods to render dogs infertile that do not involve gonadectomy. Veterinarians should discuss the benefits and possible adverse effects of gonadectomy with clients, giving consideration to the breed of dog, the owners circumstances, and the anticipated use of the dog.

New technology, old standards: Disparate activated clotting time measurements by the Hemochron Jr compared with the standard Hemochron

BACKGROUND Accurate control of the anticoagulation level is important for safe initiation of cardiopulmonary bypass. Using the Hemochron Jr., we consistently noted a higher than customary heparin dose required to achieve an activated clotting time (ACT) that, according to the literature and our quality standards, should be more than 480 seconds. This study was designed to determine whether there existed a significant difference in ACT values measured by the newer Hemochron Jr. and the older Hemochron 801 assay system. METHODS A total of 30 patients underwent cardiovascular surgical procedures requiring heparinization (300 U/kg). Multiple samples for measurement of the ACT were obtained from all patients before heparinization, after heparinization, during cardiopulmonary bypass, and after protamine administration. Arterial samples were collected, and ACT was determined simultaneously on the same sample using both Hemochron Jr. and Hemochron 801. Activated clotting time data were analyzed with a linear mixed model using an unstructured variance-covariance matrix. RESULTS Descriptive statistics on all heparinized patients revealed that the Hemochron Jr. yielded ACT results that on average were 121.28 seconds lower than the determination by the standard Hemochron 801 on the same sample of blood. This difference was -139.04 in on-pump cases and -90.51 in off-pump cases, primarily a function of the fact that higher heparin doses and therefore longer ACTs were used in patients having operations using the heart-lung machine. From the linear mixed model, the estimated average paired difference between the Hemochron Jr. and Hemochron 801 was found to be -86.03, yielding a highly significant test statistic (t(28) = -6.18; p < 0.0001). CONCLUSIONS Lower ACT values determined by Hemochron Jr. are consistent with higher, clinically acceptable ACT values as measured by the Hemochron 801. These findings would suggest that safe levels of anticoagulation are determined in part by the specific assay used.

Efficient use of siblings in testing for linkage and association.

Tests of linkage and association between a disease and either a candidate gene or marker allele can be based on sibships with at least one affected and one unaffected sibling. However, specialized techniques are required to account for within‐sibship correlation if some sibships contain more than one affected or more than one unaffected sib. In this paper, we propose Within Sibship Paired Resampling (WSPR), a technique that is designed to test the null hypothesis of no linkage or no association, even when sibships contain variable numbers of sibs. One repeatedly generates data subsets based on randomly sampling one affected and one unaffected sibling from each sibship, and each subset is analyzed individually. Then, evidence is combined by averaging results across these resampled data sets, applying a variance expression that implicitly accounts for the correlation among siblings. While the general WSPR procedure allows for numerous testing strategies, we describe two in detail. Simulation results for scenarios with varying degrees of population stratification demonstrate good power for the WSPR testing methods compared to the sib TDT (S‐TDT) and the sibship disequilibrium test (SDT). Genet. Epidemiol. 20:175–191, 2001.

Questioning Race: Ancestry DNA and Dialog on Race

Human genetics and racial identity converge pointedly in the family narrative. Until recently, genetics, racial identity, and family narrative were all rather malleable concepts in the public arena. All were presented in anecdotal form for the most part, and were often based on certain social conventions. The interjection of popularly available ancestry DNA data adds an additional piece of information to the discussion of genetics, race, and narrative. Using the framework of both narrative theory and theory of social construction, this work uses quantitative and qualitative data to explore how individuals react to ancestry DNA findings and to consider if and how this information will change narratives, behaviors, and perspectives. We also explore whether ones racial identification makes a difference in initial accuracy and if there is a difference among racial groupings in terms of change in census identification based on knowledge of their DNA profile.

Efficacy of major anthelmintics for reduction of fecal shedding of strongyle-type eggs in horses in the Mid-Atlantic region of the United States

In the last decade there have been numerous reports of anthelmintic resistant cyathostomins in many parts of the world. The objective of the present study was to evaluate the efficacy of the commercially available anthelmintics against cyathostomin egg shedding in the Mid-Atlantic region of the United States. A total of 989 horses from 67 different farms located in southeastern Pennsylvania, northern Delaware, and northeastern Maryland were treated with fenbendazole, oxibendazole, pyrantel pamoate, ivermectin, or moxidectin at their recommended dosages. Fecal egg count reduction testing was used to determine the efficacy of each anthelmintic on those horses with fecal egg counts of ≥ 200 eggs per gram on the day of treatment (272 horses). Decreased efficacy (reduction of strongyle-type fecal egg counts by less than 90%) was found for fenbendazole, oxibendazole, and pyrantel pamoate, with only 6%, 21% and 43% of horses showing reductions of greater than 90%, respectively. The macrocyclic lactones showed high efficacy in all horses sampled in this study. The decreased anthelmintic efficacy detected in this study adds further evidence for the existence of resistant cyathostomins throughout much of the eastern United States. Findings from this study can be used to create a more sustainable approach for parasite control programs.

Incorrect inference in prevalence trend analysis due to misuse of the odds ratio.

Because public health agencies usually monitor health outcomes over time for surveillance, program evaluation, and policy decisions, a correct health outcome trend analysis is vital. If the analysis is done incorrectly and/or results are misinterpreted, a faulty trend analysis could jeopardize key aspects of public health initiatives such as program planning, implementations, policy development, and clinical decision making. It is essential then that accurate health outcome trend analysis be implemented in any data-driven decision-making process. Unfortunately, there continues to be common statistical mistakes in prevalence trend analysis. In this article, using recently published results from the Pediatric Nutrition Surveillance System, we will show the effect that an incorrect trend analysis and subsequent interpretation of results can have. We will also propose more appropriate statistical processes, such as the log-binomial model, for these situations.

Anti-bovine herpesvirus and anti-bovine viral diarrhea virus antibody responses in pregnant Holstein dairy cattle following administration of a multivalent killed virus vaccine

OBJECTIVE To determine the effect of a commercially available multivalent killed virus vaccine on serum neutralizing (SN) and colostrum neutralizing (CN) antibodies against bovine herpesvirus (BHV) type 1 and bovine viral diarrhea virus (BVDV) types 1 and 2 in pregnant dairy cattle. ANIMALS 49 Holstein dairy cattle. PROCEDURES :25 cattle were vaccinated (IM injection) at least 60 days prior to calving (ie, at the end of the lactation period or according to the expected calving date for heifers) and again 5 weeks later. The remaining 24 cattle were not vaccinated (control group). Titers of SN antibodies were measured at the 5-week time point. Titers of SN and CN antibodies were measured at parturition. RESULTS 5 weeks after initial vaccination, titers of SN antibodies against BHV-1 and BVDV types 1 and 2 were 1:512, 1:128, and 1:2,048, respectively, in vaccinates and 1:64, 1:128, and 1:64, respectively, in unvaccinated controls. Equivalent SN antibody titers at parturition were 1:256, 1:64, and 1:512, respectively, in vaccinates and 1:128, 1:128, and 1:64, respectively, in controls. Median titers of CN antibodies against BHV-1 and BVDV types 1 and 2 were 1:1,280, 1:10,240, and 1:20,480, respectively, in vaccinates and 1:80, 1:1,280, and 1:2,560, respectively, in controls. CONCLUSIONS AND CLINICAL RELEVANCE Titers of antibodies against viral respiratory pathogens were significantly enhanced in both serum (BHV-1 and BVDV type 2) and colostrum (BHV-1 and BVDV types 1 and 2) in cattle receiving a killed virus vaccine (with no adverse reactions) before parturition. To maximize protection of bovine neonates, this method of vaccination should be considered.

Testing for violations of the homogeneity needed for conditional logistic regression

In epidemiologic studies where the outcome is binary, the data often arise as clusters, as when siblings, friends or neighbors are used as matched controls in a case-control study. Conditional logistic regression (CLR) is typically used for such studies to estimate the odds ratio for an exposure of interest. However, CLR assumes the exposure coefficient is the same in every cluster, and CLR-based inference can be badly biased when homogeneity is violated. Existing methods for testing goodness-of-fit for CLR are not designed to detect such violations. Good alternative methods of analysis exist if one suspects there is heterogeneity across clusters. However, routine use of alternative robust approaches when there is no appreciable heterogeneity could cause loss of precision and be computationally difficult, particularly if the clusters are small. We propose a simple non-parametric test, the test of heterogeneous susceptibility (THS), to assess the assumption of homogeneity of a coefficient across clusters. The test is easy to apply and provides guidance as to the appropriate method of analysis. Simulations demonstrate that the THS has reasonable power to reveal violations of homogeneity. We illustrate by applying the THS to a study of periodontal disease.