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Serial health assessment of a managed population of American horseshoe crabs (HSC; Limulus polyphemus ) was performed. Twenty HSC were examined once a month for 7 mon; this included a physical exam with a standardized scoring sheet, HR, morphometrics, and hemolymph evaluation with hemocyte count, copper concentration, and biochemistry panel. The HSC in this population had varying levels of external lesions at enrollment. All HSC were clinically and behaviorally stable over the study period, with no apparent differences in evaluated parameters in relation to degree of external lesions. Although the standardized scoring sheet was found to be helpful to complete the evaluation, the qualitative criteria potentially masks clinically important gradations in some parameters. HR ranged from 4 to 60 bpm, with high intra- and interindividual variability. Increased prosomal widths (PW) were found to be correlated with lower HR. Plots of weight (W) in grams divided by PW in centimeters are roughly linear, and W:PW shows promise as a method of body condition evaluation in a hard-shelled animal. Serial collection of ∼2 ml of hemolymph led to no appreciable clinical decline in any animal. Total protein levels were stable and higher than previously reported for HSC in managed care. Glucose values were stable throughout the study period, which is interpreted as reflecting adequate nutritional intake in the study animals. Further studies are needed to determine the clinical utility of standardized vertebrate biochemistry panels in invertebrate species.

Introduction: Theileria orientalis Ikeda genotype is an emerging cattle disease in the US. Since 2017, when T. orientalis Ikeda was discovered in beef cattle in two counties in Virginia, cattle infections have risen to include ~67% of Virginia counties and 14 states. Consistent with New Zealand studies, many infected herds in Virginia were >90% positive upon initial testing without overt evidence of infection. Central bull tests present a unique opportunity to study the effects of T. orientalis Ikeda infections, as bulls from multiple source herds are consolidated. The objective of this study was to determine if infection with T. orientalis Ikeda affected the average daily gain (ADG), adjusted yearling weight (AYW) and breeding soundness of bulls at two test stations in Virginia over a period of years., Materials and Methods: The bulls were fed and housed similarly to compare their growth performance and breeding soundness. For T. orientalis Ikeda testing, DNA was extracted from whole blood for quantitative polymerase chain reaction., Results: The number of bulls infected with T. orientalis Ikeda at initial delivery to the stations increased significantly over the years studied. Multivariable linear regression models, using Angus bulls from Virginia test stations, indicated no significant effect on ADG or AYW in bulls that became test positive during the test or were positive for the duration, compared to Angus bulls that were negative for the duration. At LOC A, the odds of passing a breeding soundness exam (BSE) were not significantly different for bulls that turned positive during the test or were positive for the duration, compared to bulls that were negative for the duration of the test. At LOC B, bulls that became positive during the test were 2.4 times more likely (95% CI: 1.165-4.995, p = 0.016) to pass their BSE compared to bulls that remained negative throughout the test., Discussion: We do not suppose that an obscured infection of T. orientalis Ikeda is protective for bulls to pass a BSE. However, this study demonstrates an obscured infection of T. orientalis Ikeda does not negatively affect weight gain or achievement of a satisfactory BSE rating at the central bull test stations in Virginia., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Guynn, Greiner, Currin, Todd, Assenga, Hungerford and Lahmers.)

Theileria orientalis , genotype Ikeda, was recently detected in North America. Determining the emerging distribution of this pathogen is critical for understanding spread and developing management strategies. Whole blood samples were collected from cattle at Virginia livestock markets from September 2018 through December 2020. Animals were tested for T. orientalis using a universal and then genotype specific real-time PCR based on the MPSP gene. Prevalence for each genotype was analyzed for temporal trends and mapped by county. Spatial patterns were compared between genotypes and assessed for associations with habitat features, cattle movements through cattle markets and county proximity. Overall, 212 of 1980 samples tested positive for T. orientalis with an overall prevalence of 8.7% (172/1980) for genotype Ikeda, 1.8% (36/1980) for genotype Chitose, 0.2% (3/1980) for genotype Buffeli. The Ikeda genotype increased over time in northern and southwestern Virginia markets. The Ikeda and Chitose genotypes occurred in different regions, with little overlap, but for each genotype, spatial distribution was associated with a combination of cattle movements and environmental factors. Genotype specific qPCR testing and surveillance of cattle from across a wide area of Virginia are providing information on temporal, spatial, and other patterns for this emerging disease.

Pooled testing can enhance the efficiency of diagnosing individuals with diseases of low prevalence. Often, pooling is implemented using standard groupings (2, 5, 10, etc.). On the other hand, optimization theory can provide specific guidelines in finding the ideal pool size and pooling strategy. This article focuses on optimizing the precision of disease prevalence estimators calculated from multiplex pooled testing data. In the context of a surveillance application of animal diseases, we study the estimation efficiency (i.e., precision) and cost efficiency of the estimators with adjustments for the number of expended tests. This enables us to determine the pooling strategies that offer the highest benefits when jointly estimating the prevalence of multiple diseases, such as theileriosis and anaplasmosis. The outcomes of our work can be used in designing pooled testing protocols, not only in simple pooling scenarios but also in more complex scenarios where individual retesting is performed in order to identify positive cases. A software application using the shiny package in R is provided with this article to facilitate implementation of our methods. Supplementary materials accompanying this paper appear online. Supplementary materials for this article are available at 10.1007/s13253-022-00511-4., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© International Biometric Society 2022, Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

The goal of this study was to evaluate longitudinal patterns of avian mycobacteriosis spread through a social network. Specifically, we wanted to determine whether the patterns of connectivity over time can predict future infections, and whether this pattern can distinguish between different sources of infection. The study population included 13,409 individuals nested in a larger population of birds that were closely monitored in zoological facilities for over 22 years (1992-2014). A retrospective cohort study design and social network connectivity were used to estimate the association between exposure to an infected bird, and development of mycobacteriosis. Avian mycobacteriosis was diagnosed from histopathology and network connectivity was defined by enclosure histories over discrete time periods. Single-variable and multivariable longitudinal, mixed effects logistic regression models examined whether exposure to infected birds, both directly- and indirectly-connected, was associated with development of mycobacteriosis at the next time step. Our adjusted model showed an increased odds of developing mycobacteriosis (odds ratio = 2.15; 95 % CI: 1.48-3.12; p < 0.001) for birds that were directly exposed (i.e., housed in the same aviary) to another infected bird, compared to those with no exposure. Exposure to a positive, indirectly-connected bird at a previous time step was independently associated with an increased risk of mycobacteriosis (odds ratio = 1.56; 95 % CI: 1.11-2.19). This association persisted in adjusted models even when the indirect contacts were housed in distinctly different aviaries and never had contact with the subject of interest or its environment. Adjusted, risk-stratified models further characterized the type of exposure that increased the risk of avian mycobacteriosis. Birds that were exposed in small aviaries were more likely to develop mycobacteriosis than those exposed in larger aviaries and those with no exposure. The lesion distribution and species of the contact (same species versus different species) were also significant predictors of disease risk. Some findings were sensitive to model variation of time divisions and initiation time. Our study shows avian mycobacteriosis spread through the social network in quantifiable and discernable patterns. We provide empirical evidence that a contagious process drives some of the observed infection, but we also show low transmissibility based on sustained patterns of low incidence over time even when large groups of birds are exposed. Targeted risk mitigation efforts based on the characteristics of the exposure may be effective at reducing risk of avian mycobacteriosis while enhancing population sustainability., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study combined a social network analysis and whole-genome sequencing (WGS) to test for general patterns of contagious spread of a mycobacterial infection for which pathways of disease acquisition are not well understood. Our population included 275 cases diagnosed with avian mycobacteriosis that were nested in a source population of 16,430 birds at San Diego Zoo Wildlife Alliance facilities from 1992 through mid-2014. Mycobacteria species were determined using conventional methods and whole genome sequencing (WGS). Mycobacterium avium avium (MAA) and Mycobacterium genavense were the most common species of mycobacteria identified and were present in different proportions across bird taxa. A social network for the birds was constructed from the source population to identify directly and indirectly connected cases during time periods relevant to disease transmission. Associations between network connectivity and genetic similarity of mycobacteria (as determined by clusters of genotypes separated by few single nucleotide polymorphisms, or SNPs) were then evaluated in observed and randomly generated network permutations. Findings showed that some genotypes clustered along pathways of bird connectivity, while others were dispersed throughout the network. The proportion of directly connected birds having a similar mycobacterial genotype was 0.36 and significant (p<0.05). This proportion was higher (0.58) and significant for MAA but not for M. genavense. Evaluations of SNP distributions also showed genotypes of MAA were more related in connected birds than expected by chance; however, no significant patterns of genetic relatedness were identified for M. genavense, although data were sparse. Integrating the WGS analysis of mycobacteria with a social network analysis of their host birds revealed significant genetic clustering along pathways of connectivity, namely for MAA. These findings are consistent with a contagious process occurring in some, but not all, case clusters., Competing Interests: The authors have declared that no competing interests exist.

Disease transmission can be identified in a social network from the structural patterns of contact. However, it is difficult to separate contagious processes from those driven by homophily, and multiple pathways of transmission or inexact information on the timing of infection can obscure the detection of true transmission events. Here, we analyze the dynamic social network of a large, and near-complete population of 16,430 zoo birds tracked daily over 22 years to test a novel "friends-of-friends" strategy for detecting contagion in a social network. The results show that cases of avian mycobacteriosis were significantly clustered among pairs of birds that had been in direct contact. However, since these clusters might result due to correlated traits or a shared environment, we also analyzed pairs of birds that had never been in direct contact but were indirectly connected in the network via other birds. The disease was also significantly clustered among these friends of friends and a reverse-time placebo test shows that homophily could not be causing the clustering. These results provide empirical evidence that at least some avian mycobacteriosis infections are transmitted between birds, and provide new methods for detecting contagious processes in large-scale global network structures with indirect contacts, even when transmission pathways, timing of cases, or etiologic agents are unknown., Competing Interests: The authors have declared that no competing interests exist.

Objective: To estimate the association between age at antiretroviral therapy (ART) initiation and immunologic response over time by stratum of baseline CD4 cell counts., Design: Retrospective cohort analysis of data pooled from four President's Emergency Plan for AIDS Relief funded countries in Sub-Saharan Africa., Methods: General linear models were used to estimate the mean CD4 cell count by age group within groups defined by baseline CD4 cell count. Kaplan-Meier methods were used to estimate time to achieving a CD4 cell count of at least 500 cells/μl by age group and stratified by baseline CD4 cell count., Results: A total of 126 672 previously treatment-naive patients provided 466 482 repeated CD4 cell count measurements over 4 years of ART. The median baseline CD4 cell count for all age groups was less than 200 cells/μl. Patients aged 30-39, 40-49, 50-59, and 60 and older at ART initiation had significantly lower mean CD4 cell counts in most strata and at most time points than those 20-29 years old. Compared with those 20-29, all older age groups had a significantly longer time to, and lower rate of, achieving a CD4 cell count of 500 cells., Conclusion: Age is associated with the magnitude of CD4 cell gain and the amount of time it takes to gain cells at different levels of baseline CD4 cell count. The delay in achieving a robust immune response could have significant implications for the risk of tuberculosis reactivation as well as comorbidities associated with age in the management of older HIV-infected patients.

OBJECTIVE To determine the incidence of and risk factors for clinical feline herpesvirus (FHV) infection in zoo-housed cheetahs and determine whether dam infection was associated with offspring infection. DESIGN Retrospective cohort study. ANIMALS 144 cheetah cubs born in 6 zoos from 1988 through 2007. PROCEDURES Data were extracted from the health records of cheetahs and their dams to identify incident cases of clinical FHV infection and estimate incidence from birth to 18 months of age. Univariate and multivariable Cox proportional hazards models, controlling for correlations among cheetahs with the same dam, were used to identify risk factors for incident FHV infection. RESULTS Cumulative incidence of FHV infection in cheetah cubs was 35% (50/144). No significant association between dam and offspring infection was identified in any model. Factors identified as significant through multivariable analysis varied by age group. For cheetahs up to 3 months of age, the most important predictor of FHV infection was having a dam that had received a preparturition FHV vaccine regimen that included a modified-live virus vaccine versus a dam that had received no preparturition vaccine. Other risk factors included being from a small litter, being born to a primiparous dam, and male sex. CONCLUSIONS AND CLINICAL RELEVANCE This study provided the first population-level characterization of the incidence of and risk factors for FHV infection in cheetahs, and findings confirmed the importance of this disease. Recognition that clinical FHV infection in the dam was not a significant predictor of disease in cubs and identification of other significant factors have implications for disease management.

Histomoniasis, commonly referred to as blackhead disease, is a serious threat to the turkey and game bird industries worldwide, and it is having an increasingly negative impact on the chicken industry as well. The Food and Drug Administration's (FDA) Center for Veterinary Medicine (CVM), charged with the approval and regulation of new animal drugs in the United States, understands the rising need for the availability of therapeutic options against histomoniasis. CVM has actively engaged in discussions with the poultry industry, academic institutions, and animal health companies regarding the current status of histomoniasis in the United States and varied success of past and current management, prophylactic, and therapeutic interventions that have been used against the disease. As effective options against the disease are severely limited, CVM encourages the poultry industry, academic institutions, and animal health companies to work together to research and develop viable management, prophylactic, and therapeutic strategies, such as litter management, deworming programs, vaccines or other biologics, novel technologies, and animal drugs. CVM also recognizes the potential challenges that the poultry industry, academic institutions, and animal health companies may encounter while working towards the approval of safe and effective drug products for the treatment and control of histomoniasis. With that recognition, CVM encourages interested parties to begin discussions with CVM early in order to align research of the drug product against histomoniasis with the drug approval requirements, such that it leads to the approval of a new animal drug in an efficient and expedient manner. This article provides information about the FDA's regulatory process for the approval of new animal drugs in the United States, with especial emphasis on drug products for the treatment and control of histomoniasis in turkeys, chickens, and game birds.

One of the longest-persisting avian influenza viruses in history, highly pathogenic avian influenza virus (HPAIV) A(H5N1), continues to evolve after 18 yr, advancing the threat of a global pandemic. Wild waterfowl (family Anatidae) are reported as secondary transmitters of HPAIV and primary reservoirs for low-pathogenic avian influenza viruses, yet spatial inputs for disease risk modeling for this group have been lacking. Using geographic information software and Monte Carlo simulations, we developed geospatial indices of waterfowl abundance at 1 and 30 km resolutions and for the breeding and wintering seasons for China, the epicenter of H5N1. Two spatial layers were developed: cumulative waterfowl abundance (WAB), a measure of predicted abundance across species, and cumulative abundance weighted by H5N1 prevalence (WPR), whereby abundance for each species was adjusted based on prevalence values and then totaled across species. Spatial patterns of the model output differed between seasons, with higher WAB and WPR in the northern and western regions of China for the breeding season and in the southeast for the wintering season. Uncertainty measures indicated highest error in southeastern China for both WAB and WPR. We also explored the effect of resampling waterfowl layers from 1 to 30 km resolution for multiscale risk modeling. Results indicated low average difference (less than 0.16 and 0.01 standard deviations for WAB and WPR, respectively), with greatest differences in the north for the breeding season and southeast for the wintering season. This work provides the first geospatial models of waterfowl abundance available for China. The indices provide important inputs for modeling disease transmission risk at the interface of poultry and wild birds. These models are easily adaptable, have broad utility to both disease and conservation needs, and will be available to the scientific community for advanced modeling applications.

The identification of feline herpesvirus (FHV) infected cheetahs (Acinonyx jubatus) and characterization of shedding episodes is difficult due to nonspecific clinical signs and limitations of diagnostic tests. The goals of this study were to develop a case definition for clinical FHV and describe the distribution of signs. Medical records from six different zoologic institutions were reviewed to identify cheetahs with diagnostic test results confirming FHV. Published literature, expert opinion, and results of a multiple correspondence analysis (MCA) were used to develop a clinical case definition based on 69 episodes in FHV laboratory confirmed (LC) cheetahs. Four groups of signs were identified in the MCA: general ocular signs, serious ocular lesions, respiratory disease, and cutaneous lesions. Ocular disease occurred with respiratory signs alone, with skin lesions alone, and with both respiratory signs and skin lesions. Groups that did not occur together were respiratory signs and skin lesions. The resulting case definition included 1) LC cheetahs; and 2) clinically compatible (CC) cheetahs that exhibited a minimum of 7 day's duration of the clinical sign groupings identified in the MCA or the presence of corneal ulcers or keratitis that occurred alone or in concert with other ocular signs and skin lesions. Exclusion criteria were applied. Application of the case definition to the study population identified an additional 78 clinical episodes, which represented 58 CC cheetahs. In total, 28.8% (93/322) of the population was identified as LC or CC. The distribution of identified clinical signs was similar across LC and CC cheetahs. Corneal ulcers and/or keratitis, and skin lesions were more frequently reported in severe episodes; in mild episodes, there were significantly more cheetahs with ocular-only or respiratory-only disease. Our results provide a better understanding of the clinical presentation of FHV, while presenting a standardized case definition that can both contribute to earlier diagnoses and be used for population-level studies.

Emergence of avian influenza viruses with high lethality to humans, such as the currently circulating highly pathogenic A(H5N1) (emerged in 1996) and A(H7N9) cause serious concern for the global economic and public health sectors. Understanding the spatial and temporal interface between wild and domestic populations, from which these viruses emerge, is fundamental to taking action. This information, however, is rarely considered in influenza risk models, partly due to a lack of data. We aim to identify areas of high transmission risk between domestic poultry and wild waterfowl in China, the epicenter of both viruses. Two levels of models were developed: one that predicts hotspots of novel virus emergence between domestic and wild birds, and one that incorporates H5N1 risk factors, for which input data exists. Models were produced at 1 and 30 km spatial resolution, and two temporal seasons. Patterns of risk varied between seasons with higher risk in the northeast, central-east, and western regions of China during spring and summer, and in the central and southeastern regions during winter. Monte-Carlo uncertainty analyses indicated varying levels of model confidence, with lowest errors in the densely populated regions of eastern and southern China. Applications and limitations of the models are discussed within.

Objective: To critically evaluate and summarize available information on the safety of potassium bromide in dogs., Design: Systematic review., Sample: 111 references reporting safety information relevant to potassium bromide published between 1938 and 2011., Procedures: PubMed searches without date limitations were conducted with the terms "potassium bromide" and "sodium bromide" in December 2009 and October 2011. Additional articles were identified through examination of article reference lists and book chapters on seizures in dogs and pharmacology., Results: Reversible neurologic signs were the most consistently reported toxicoses and were generally associated with adjunctive potassium bromide treatment or high serum bromide concentrations. Dermatologic and respiratory abnormalities were rare in dogs. Insufficient information was available to assess the effects of potassium bromide on behavior or to determine the incidence of vomiting, weight gain, polyphagia, pancreatitis, polyuria, polydipsia, or reproductive abnormalities associated with potassium bromide administration. Evidence suggested that administration of potassium bromide with food may alleviate gastrointestinal irritation and that monitoring for polyphagia, thyroid hormone abnormalities, and high serum bromide concentrations may be beneficial., Conclusions and Clinical Relevance: Results suggested that potassium bromide is not an appropriate choice for treatment of every dog with seizures and that practitioners should tailor therapeutic regimens and clinical monitoring to each dog. Abrupt dietary changes or fluid therapy may compromise seizure control or increase the likelihood of adverse events. Availability of an appropriately labeled, approved potassium bromide product could provide better assurance for veterinarians and their clients of the quality, safety, and effectiveness of the product for veterinary use.

Background: The probability of contracting malaria in a given individual is determined not only by the individual's characteristics, but also the ecological factors that characterize the level of human-vector contact in the population. Examination of the relationship between "individual" and "supra-individual" variables over time is important for understanding the local malaria epidemiology. This is essential for planning effective intervention strategies specifically for each location., Methods: A retrospective cohort study was conducted, which followed a community-cohort of about 3,500 residents in seven hamlets along the Thai-Myanmar border between 1999 and 2006. Potential malaria determinants measured at different levels (temporal variables, individual variables, and hamlet variables) were incorporated into multilevel models to estimate their effects on an individual's risk of malaria attack., Results: The monthly minimum temperature was significantly associated with the seasonal variation of malaria risk. An individual risk of malaria attack decreased by about 50% during the period that active surveillance was conducted; an additional 15% and 25% reduction of Plasmodium falciparum and Plasmodium vivax incidence, respectively, was observed after the use of artesunate-mefloquine combination therapy (ACT) for treatment of P. falciparum. Male children (age < 16 years old) were at highest risk of both P. falciparum and P. vivax attack. An increase in the hamlet's incidence of P. falciparum and P. vivax by 1 per 100 persons in a previous month resulted in 1.14 and 1.34 times increase in the risk of P. falciparum and P. vivax, respectively, among individuals in a particular hamlet., Conclusion: In a small area with low malaria transmission intensity, the variation in mosquito abundance is relatively similar across the residential areas; incidence of malaria between hamlets, which reflects the community level of human infectious reservoirs, is an important predictor for the malaria risk among individuals within these hamlets. Therefore, local malaria control strategies should focus on interventions that aim to reduce the gametocyte carriage in the population, such as early detection and treatment programmes and the use of ACT for P. falciparum.

Objective: To characterize infection patterns and identify factors associated with avian mycobacteriosis among zoo birds that were housed with infected enclosure mates., Design: Matched case-control study., Animals: 79 birds with avian mycobacteriosis (cases) and 316 nondiseased birds (controls) of similar age and taxonomic group that were present in the bird collection of the Zoological Society of San Diego from 1991 through 2005., Procedures: Inventory and necropsy records from all eligible, exposed birds (n = 2,413) were examined to determine disease incidence and prevalence in the exposed cohort. Cases were matched in a 1:4 ratio to randomly selected controls of similar age and taxonomic grouping. Risk factors for mycobacteriosis (demographic, temporal, enclosure, and exposure characteristics as well as translocation history) were evaluated with univariate and multivariable conditional logistic regression analyses., Results: Disease prevalence and incidence were estimated at 3.5% and 8 cases/1,000 bird-years at risk, respectively. In the multivariable model, cases were more likely to have been imported into the collection, exposed to mycobacteriosis at a young age, exposed to the same bird species, and exposed in small enclosures than were controls. Odds for disease increased with an increasing amount of time spent with other disease-positive birds., Conclusions and Clinical Relevance: The low incidence of mycobacteriosis and the risk factors identified suggested that mycobacteria may not be easily transmitted through direct contact with infected enclosure mates. Identification of risk factors for avian mycobacteriosis will help guide future management of this disease in zoo bird populations.

Background: Effective malaria control has successfully reduced the malaria burden in many countries, but to eliminate malaria, these countries will need to further improve their control efforts. Here, a malaria control programme was critically evaluated in a very low-endemicity Thai-Myanmar border population, where early detection and prompt treatment have substantially reduced, though not ended, Plasmodium falciparum transmission, in part due to carriage of late-maturing gametocytes that remain post-treatment. To counter this effect, the WHO recommends the use of a single oral dose of primaquine along with an effective blood schizonticide. However, while the effectiveness of primaquine as a gametocidal agent is widely documented, the mismatch between primaquine's short half-life, the long-delay for gametocyte maturation and the proper timing of primaquine administration have not been studied., Methods: Mathematical models were constructed to simulate 8-year surveillance data, between 1999 and 2006, of seven villages along the Thai-Myanmar border. A simple model was developed to consider primaquine pharmacokinetics and pharmacodynamics, gametocyte carriage, and infectivity., Results: In these populations, transmission intensity is very low, so the P. falciparum parasite rate is strongly linked to imported malaria and to the fraction of cases not treated. Given a 3.6-day half-life of gametocyte, the estimated duration of infectiousness would be reduced by 10 days for every 10-fold reduction in initial gametocyte densities. Infectiousness from mature gametocytes would last two to four weeks and sustain some transmission, depending on the initial parasite densities, but the residual mature gametocytes could be eliminated by primaquine. Because of the short half-life of primaquine (approximately eight hours), it was immediately obvious that with early administration (within three days after an acute attack), primaquine would not be present when mature gametocytes emerged eight days after the appearance of asexual blood-stage parasites. A model of optimal timing suggests that primaquine follow-up approximately eight days after a clinical episode could further reduce the duration of infectiousness from two to four weeks down to a few days. The prospects of malaria elimination would be substantially improved by changing the timing of primaquine administration and combining this with effective detection and management of imported malaria cases. The value of using primaquine to reduce residual gametocyte densities and to reduce malaria transmission was considered in the context of a malaria transmission model; the added benefit of the primaquine follow-up treatment would be relatively large only if a high fraction of patients (>95%) are initially treated with schizonticidal agents., Conclusion: Mathematical models have previously identified the long duration of P. falciparum asexual blood-stage infections as a critical point in maintaining malaria transmission, but infectiousness can persist for two to four weeks because of residual populations of mature gametocytes. Simulations from new models suggest that, in areas where a large fraction of malaria cases are treated, curing the asexual parasitaemia in a primary infection, and curing mature gametocyte infections with an eight-day follow-up treatment with primaquine have approximately the same proportional effects on reducing the infectious period. Changing the timing of primaquine administration would, in all likelihood, interrupt transmission in this area with very good health systems and with very low endemicity.

The objective of the present study was to determine whether offspring of dams infected with Mycobacterium avium subsp. paratuberculosis (Map) have an increased risk for Map infection. Antemortem and postmortem disease surveillance data were used to identify positive and test-negative ruminants born at the Zoological Society of San Diego (ZSSD) between 1991 and 2007 and to estimate cumulative lifetime incidence. A matched case-control study, nested within the population, was conducted and conditional logistic regression analyses were used to quantify the association between infection status of offspring and their dams. Cases (infected ruminants, n = 47) were matched to controls (test-negative ruminants, n = 152) by species, birth date, birth enclosure, and follow-up time to control for confounding factors. The overall cumulative lifetime incidence of infection was estimated at 2.2%, but it decreased over time and varied by species. There was a significant association between infection status of offspring and their dams (odds ratio [OR] = 6.8, P < 0.01), which is consistent with studies in domestic livestock species. The association was stronger for animals whose dam was diagnosed within 2 years of their birth (OR = 9.0, P < 0.01) than for animals whose dam was diagnosed more than 2 years after their birth (OR = 6.0, P < 0.01) compared to animals with test-negative dams. For positive animals born to a positive dam, 85.3% of the Map infections were attributable to having a positive dam. For the entire population of ZSSD ruminants, 28.8% [corrected] of the cases were attributable to having a positive dam. Findings will help guide future management of Map infection in zoo ruminant populations.

We examined factors that may independently or synergistically contribute to amphibian population declines. We used epidemiologic case-control methodology to sample and analyze a large database developed and maintained by the Arizona Game and Fish Department that describes historical and currently known ranid frog localities in Arizona, U.S.A. Sites with historical documentation of target ranid species (n= 324) were evaluated to identify locations where frogs had disappeared during the study period (case sites) and locations where frog populations persisted (control sites). Between 1986 and 2003, 117 (36%) of the 324 sites became case sites, of which 105 were used in the analyses. An equal number of control sites were sampled to control for the effects of time. Risk factors, or predictor variables, were defined from environmental data summarized during site surveys and geographic information system data layers. We evaluated risk factors with univariate and multifactorial logistic-regression analyses to derive odds ratios (OR). Odds for local population disappearance were significantly related to 4 factors in the multifactorial model. Disappearance of frog populations increased with increasing elevation (OR = 2.7 for every 500 m, p < 0.01). Sites where disappearances occurred were 4.3 times more likely to have other nearby sites that also experienced disappearances (OR = 4.3, p < 0.01), whereas the odds of disappearance were 6.7 times less (OR = 0.15, p < 0.01) when there was a source population nearby. Sites with disappearances were 2.6 times more likely to have introduced crayfish than were control sites (OR = 2.6, p= 0.04). The identification of factors associated with frog disappearances increases understanding of declines occurring in natural populations and aids in conservation efforts to reestablish and protect native ranids by identifying and prioritizing implicated threats.

The objective of the current study was to identify factors associated with avian mycobacteriosis in zoo birds. Inventory data, population health records, and necropsy data from eligible birds in the Zoological Society of San Diego's (ZSSD) collection from 1991-2005 (n = 13,976) were used to describe disease incidence, prevalence, and postmortem findings. A matched case-control study was then conducted to identify factors describing demographic, temporal, and enclosure characteristics, along with move and exposure histories. Cases (disease-positive birds; n = 167) were matched in a 17 ratio with controls (disease-negative birds; n = 1169) of similar age and taxonomic grouping. Potential risk factors were evaluated using univariate and multivariable conditional logistic regression. Disease prevalence and incidence were estimated for the study period at 1.2% and 3 cases/(1,000 bird-years at risk), respectively. Lesion characteristics and order prevalence are described. In the multivariable model, case birds were more likely to have been previously housed with a bird with mycobacterial disease involving the intestinal tract (odds ratio [OR] = 5.6, P < 0.01) or involving only nonintestinal sites (OR = 2.0, P < 0.01). Cases were more likely to have been imported into the collection than hatched at the ZSSD (OR = 4.2, P < 0.01). Cases were moved among ZSSD enclosures more than controls (OR = 1.1 for each additional move, P < 0.01). Findings will help guide future management of this disease for zoo bird populations.

The objective was to test the hypothesis that phenylbutazone (PBZ) alleviates lameness in an adjustable heart bar shoe model of equine foot pain. Eight Quarter Horse mares underwent 4-weekly treatments randomly: 0.9% saline placebo (SAL: 1 mL/45 kg body weight i.v.) with no lameness; SAL with lameness; PBZ (4.4 mg/kg body weight i.v.) with no lameness; and PBZ with lameness. Blinded heart rate (HR) and lameness score (LS) were assessed every 20 min for 2 h and then hourly through 9 h. At 1 h SAL or PBZ was administered. Jugular venous samples were obtained at hours 0, 1, 2, 4, 6, and 8 and were evaluated for packed cell volume (PCV), cortisol, and drug concentrations. Repeated measures anova and t-tests were used to identify PBZ effects at a significance level of P<0.05. PBZ-treated LS was lower 2-8 h post-treatment, and HR was lower from 2 through 6 h post-treatment (P<0.05). Phenylbutazone did not change PCV and had minimal effect on cortisol. Mean plasma PBZ and oxyphenbutazone concentrations 7 h after treatment were 7.2-7.5 and 1.6-1.9 microg/mL, respectively. It was concluded that PBZ was efficacious in alleviating lameness in this model. Cortisol and PCV were not discriminating enough to distinguish between PBZ-treated and SAL-treated trials.

We describe correlative clinicopathological/virological findings from a simian varicella virus (SVV)-seronegative monkey that developed disseminated varicella 105 days after gamma-irradiation. Twelve other monkeys in the colony were also irradiated, none of which developed varicella. Before irradiation, sera from the monkey that developed disseminated infection and one asymptomatic monkey were available. Analysis indicated that subclinical reactivation of latent SVV from an asymptomatic irradiated monkey likely led to disseminated varicella in the seronegative irradiated monkey. These findings parallel those from humans with disseminated varicella infection and support the usefulness of SVV infection as a model for human varicella-zoster virus infection, particularly virus reactivation after gamma-irradiation.

Contact between humans and nonhuman primates (NHPs) frequently occurs at monkey temples (religious sites that have become associated with free-ranging populations of NHPs) in Asia, creating the potential for NHP-human disease transmission. In March 2003 a multidisciplinary panel of experts participated in a workshop designed to model the risk of NHP-human pathogen transmission. The panel developed a risk assessment model to describe the likelihood of cross-species transmission of simian foamy virus (SFV) from temple macaques (Macaca fascicularis) to visitors at monkey temples. SFV is an enzootic simian retrovirus that has been shown to be transmitted from NHPs to humans. In operationalizing the model field data, laboratory data and expert opinions were used to estimate the likelihood of SFV transmission within this context. This model sets the stage for a discussion about modeling as a risk assessment tool and the kinds of data that are required to accurately predict transmission., (Copyright 2006 Wiley-Liss, Inc.)

Objective: To evaluate associations between neonatal serum IgG1 concentration and pre- and postweaning morbidity and mortality rates and average daily gains (ADGs) in beef calves and define a cutoff point for serum IgG1 concentration necessary for optimal health and performance of beef calves., Design: Nonconcurrent cohort study., Animals: 1,568 crossbred beef calves., Procedure: Single radial immunodiffusion was used to quantitate IgG1 concentration in sera collected from calves between 24 and 72 hours after birth. Logistic regression, ANCOVA, and likelihood ratios were used to analyze data., Results: In the preweaning period, lower perinatal IgG1 concentrations were significantly associated with higher morbidity rates, higher mortality rates, and lower ADGs. Calves with serum IgG1 concentration < 2,400 mg/dL were 1.6 times as likely to become ill before weaning and 2.7 times as likely to die before weaning as calves with higher serum IgG1 concentrations. Calves with serum IgG1 concentration of at least 2,700 mg/dL weighed an estimated 3.35 kg (7.38 lb) more at 205 days of age than calves with lower serum IgG1 concentration. No significant association of serum IgG1 concentration with feedlot morbidity, death, or ADG was identified., Conclusions and Clinical Relevance: By use of likelihood ratios, the threshold of serum IgG1 concentration for optimal health and performance of calves was higher than values reported previously. Implementation and maintenance of management and intervention strategies designed for early detection and treatment of calves at risk for failure of passive transfer will likely result in increases in preweaning health and performance parameters.

Shiga toxin (Stx)-producing bacteria are important human pathogens that have been linked with cattle and associated food products. We recovered Stx-producing bacteria from 27.5% of cattle, 6.8% of water, and 2.3% of wildlife samples from a cattle production area during an 11-month period. Positive samples were found during every month and on 98% of sampling days. We recovered isolates from all cattle operations sampled, and prevalence within operations ranged from approximately 5 to 33%. Cattle prevalence was associated with the presence of Stx-producing bacteria in water and the production group and environment of cattle, with an interaction between production group and environment. Odds of recovering isolates from cattle were highest for groups of adult cows and their unweaned calves in pasture environments. Overall, 49 O serogroups were identified from 527 isolates. Seventy of the isolates contained virulence genes that encoded intimin and enterohemorrhagic Escherichia coli hemolysin. These were serogroups O111, O157, O109, O103, O145, O172, O84, O26, O108, O117, O126, O159, O5, O69, O74, O98, and O-rough. Our results suggest that the prevalence of Stx-producing bacteria can be relatively high in cattle, and associated factors may not be entirely similar to those reported for serotype O157:H7. Although Stx-producing bacteria were frequently detected, the strains may not be equally pathogenic for humans given the wide variety of serogroups and virulence genes. However, focusing on O157:H7 in food safety and surveillance programs may allow other Stx-producing bacteria, which appear to be widespread in cattle, to go undetected.

Objective: To determine the distribution of Escherichia coli O157:H7 in pasture-based cattle production areas., Sample Population: Two 100-km2 agricultural areas consisting of 207 pasture, 14 beef-confinement, and 3 dairy locations within 24 cattle operations., Procedure: 13,726 samples from cattle, wildlife, and water sources were obtained during an 11-month period. Escherichia coli O157:H7 was identified by use of culture and polymerase chain reaction assays and characterized by pulsed-field gel electrophoresis (PFGE)., Results: Odds of recovering E coli O157:H7 from feeder-aged cattle were > 4 times the odds for cow-calf or dairy cattle. There was no difference in prevalence for pastured versus confined cattle after controlling for production age group. Number of samples collected (37 to 4,829), samples that yielded E coli O157:H7 (0 to 53), and PFGE subtypes (0 to 48) for each operation varied and were highly correlated. Although most PFGE subtypes were only detected once, 17 subtypes were detected on more than 1 operation. Ten of 12 operations at which E coli O157:H7 was detected had at least 1 subtype that also was detected on another operation. We did not detect differences in the probability of having the same subtype for adjacent operations, nonadjacent operations in the same study area, or operations in the other study area., Conclusions and Clinical Relevance: Strategies aimed at controlling E coli O157:H7 and specific subtypes should account for the widespread distribution and higher prevalence in feeder-aged cattle regardless of production environment and the fact that adjacent and distant cattle operations can have similar subtypes.

Background: Mortality rates have differed during distemper outbreaks among free-ranging raccoons (Procyon lotor) living around a large Chicago-area zoo, and appeared higher in year 2001 than in 1998 and 2000. We hypothesized that a more lethal variant of the local Canine distemper virus (CDV) lineage had emerged in 2001, and sought the genetic basis that led to increased virulence. However, a more complex model surfaced during preliminary analyses of CDV genomic sequences in infected tissues and of virus isolated in vitro from the raccoons., Results: Phylogenetic analyses of subgenomic CDV fusion (F) -, phosphoprotein (P) -, and complete hemagglutinin (H) - gene sequences indicated that distinct American CDV lineages caused the distemper epizootics. The 1998 outbreak was caused by viruses that are likely from an old CDV lineage that includes CDV Snyder Hill and Lederle, which are CDV strains from the early 1950's. The 2000 and 2001 viruses appear to stem from the lineage of CDV A75/17, which was isolated in the mid 1970's. Only the 2001 viruses formed large syncytia in brain and/or lung tissue, and during primary isolation in-vitro in Vero cells, demonstrating at least one phenotypic property by which they differed from the other viruses., Conclusions: Two different American CDV lineages caused the raccoon distemper outbreaks. The 1998 viruses are genetically distant to the 2000/2001 viruses. Since CDV does not cause persistent infections, the cycling of different CDV lineages within the same locale suggests multiple reintroductions of the virus to area raccoons. Our findings establish a precedent for determining whether the perceived differences in mortality rates are actual and attributable in part to inherent differences between CDV strains arising from different CDV lineages.

A total of 112 out of 5,709 Salmonella enterica isolates from domestic animal species exhibited decreased susceptibilities to ceftiofur and ceftriaxone, and each possessed the blaCMY gene. Ten Salmonella serotypes were significantly more likely to include resistant isolates. Isolates from turkeys, horses, cats, and dogs were significantly more likely to include resistant isolates.

Canine distemper virus (CDV) is an important pathogen of many carnivores. We are developing a field-based model of morbillivirus virulence and pathogenesis through a study of distemper in naturally infected free-ranging raccoons. The isolation of CDV from raccoon tissues is essential for this work. CDV has often been isolated from animals only after co-cultivation of infected tissues with peripheral blood mononuclear cells derived from specific pathogen-free dogs or similar methods. We explored the utility and consequences of a simpler and cheaper alternative: CDV isolation in Vero, MDCK, and MV1 Lu cells. Virus growth was detected first in MDCK cells, whereas viral cytopathic effects were most obvious in Vero cells. CDV growth in MV1 Lu cells was relatively protracted and occurred without the formation of cytopathic effects. In primary CDV isolates, the entire nucleotide sequence of the receptor binding haemagglutinin (H) gene, and subgenomic fusion (F) and phospho (P) protein gene sequences corresponding to nt 5399-5733 and 2132-2563 of CDV reference strain Onderstepoort, respectively, were identical to those in matched infected tissues. Virus isolation confirmed the presence of CDV in instances where RT-PCR failed to detect CDV in infected tissues. Different viral phenotypes and genotypes were detected. The conservation of H gene sequences in primary CDV isolates suggests that MDCK, MV1 Lu, and Vero cells express proper receptors for wild-type CDV.

Genetic paternity testing can provide sire identity data for offspring when females have been exposed to multiple males. However, correct paternity assignment can be influenced by factors determined in the laboratory and by size and genetic composition of breeding groups. In the present study, DNA samples from 26 commingled beef bulls and their calves from the Nebraska Reference Herd-1 (NRH1), along with previously reported Illinois Reference/Resource Families data, were used to estimate the impact of sire number and sire relatedness on microsatellite-based paternity testing. Assay performance was measured by exclusion probabilities and probabilities of unambiguous parentage (PUP) were derived. Proportion of calves with unambiguous parentage (PCUP) was also calculated to provide a readily understandable whole-herd measure of unambiguous paternity assignment. For NRH1, theoretical and observed PCUP values were in close agreement (85.3 and 85.8%, respectively) indicating good predictive value. While the qualitative effects on PUP values of altering sire number and sire relatedness were generally predictable, we demonstrate that the impacts of these variables, and their interaction effects, can be large, are non-linear, and are quantitatively distinct for different combinations of sire number and degree of sire relatedness. In view of the potentially complex dynamics and practical consequences of these relationships in both research and animal production settings, we suggest that a priori estimation of the quantitative impact of a given set of interacting breeding group-specific and assay-specific parameters on PUP may be indicated, particularly when candidate sire pools are large, sire relatedness may be high, and/or loci numbers or heterozygosity values may be limiting.

Although cattle are reservoirs, no validated method exists to monitor Shiga toxin-producing Escherichia coli O157 (STEC O157) on farms. In 29 Midwestern United States feedlot pens we compared culturing faeces from the individual cattle to: (1) culturing rope devices that cattle rub or chew; and (2) culturing a composite of faecal pats. Eighty-six per cent (68-96%) of pens were classified correctly using rope devices to detect pens with at least 16% of the cattle shedding STEC O157 [sensitivity=82% (57-96%); specificity=92% (62-100%)]. Ninety per cent of pens (73-98%) were classified correctly using composite faeces to detect pens with at least 37% of the cattle shedding STEC O157 [sensitivity=86% (42-100%); specificity=91% (71-99%)]. Ranking pens into three risk levels based on parallel interpretation of the pen-test results correlated (Spearman's r=0.76, P<0.0001) with the pen's prevalence. This strategy could identify pens of cattle posing a higher risk to food safety.

Pregnant heifers are undesirable in the feedyard. We applied simulation modeling to a partial-budget model to compare alternative strategies for managing pregnant heifers in feedyards. The model was developed with input costs (cattle, preventive medical care, morbidity, mortality, treatments, and performance), input benefits (sales of poorly performing heifers, baby calves, open (non-pregnant) heifers, recently calved heifers, and pregnant heifers), and net returns as the output. Predicted mean net returns for feeding either open heifers or aborted heifers were greater than $ 100 (live-basis sales) to $ 200 (rail-basis sales) higher than for pregnant heifers. However, there was substantial variability in net returns for all three types of heifers. Net returns were compared among three decision choices made upon arrival of the cattle at the feedyard: (1) palpate all heifers and inject with abortifacient only those pregnant (PALABT), (2) inject all heifers with abortifacient without determining pregnancy status (ABTALL), and (3) do not palpate or administer abortifacient to any of the heifers (NOTHING). Predicted returns for PALABT and ABTALL were equivalent when estimated pregnancy prevalence was 43% (median net returns=$44.92 and $ 50.46, respectively). For heifer lots with pregnancy prevalences /=49%. Net returns for PALABT and NOTHING were equivalent when the estimated prevalence of pregnancy was 2% on a live-basis sales (median net return=$50.05) and approximately 0.9% on a rail-basis sales (median net returns=$58.36 (PALABT) and $ 58.30 (NOTHING)) (with PALABT yielding positive net returns at the higher pregnancy prevalences). NOTHING yielded a positive net return relative to PALABT when the pregnancy prevalence was <1.5% (live-basis sales) and <0.5% (rail-basis sales).

Dental health was evaluated in two populations of raccoons (Procyon lotor) in western Illinois (USA); one was from a rural agricultural area with low human density and the other from a nearby state park heavily used by humans and raccoons. From 1989 through 1993, 300 raccoons were live-trapped in the agricultural area and 246 raccoons were live-trapped in the park. Oral health was assessed using gingival and calculi indices and by measuring loss of attachment and tooth wear. Raccoons from the park were significantly older and smaller, but not thinner, than raccoons from the farmed area. Gingival and periodontal indices, tooth wear, tooth loss, and caries increased significantly from juveniles to yearlings to adults, at both sites. Males had higher levels of gingivitis and loss of periodontal attachment than females, but were similar on other dental measures. There were no seasonal differences between raccoons in dental indices. Animals with high scores for one oral measure tended to have high values for all indices. Dental health was generally good for juveniles and yearlings from both sites. Among adults, periodontal indices and the prevalence of caries were significantly higher in the park, but prevalence of broken or missing teeth was similar for both populations. There was no association between body condition, and a higher dental score or more missing or broken teeth.

Data from 116 mares that had caesarean section or vaginal delivery at 2 university hospitals were analysed in 5 groups, as follows: dystocia corrected by caesarean section, Group DCS (n = 48); elective caesarean section, Group ECS (n = 10); caesarean section concurrently with colic surgery, Group CCS (n = 8); assisted vaginal delivery, Group AVD (n = 22); and controlled vaginal delivery under general anaesthesia, Group CVD (n = 28). Survival rate in all mares that had caesarean section, excluding Group CCS, was 88% (51/58). All mares in Group ECS survived and Group CCS had the lowest survival rate (38%). In 98 mares with dystocia, Groups DCS (15%) and AVD (14%) had significantly lower (P<0.05) mortality rates than Group CVD (29%). There were no differences between groups for duration of dystocia. The placenta was retained in 75 (65%) of 116 mares, and for a longer period following elective caesarean section than following assisted vaginal delivery. Multiple complications (> or = 3) were recorded in 6 mares in Group CVD but not in the other groups. Of the 102 foals delivered from 98 mares with dystocia, 11 (11%) were alive at delivery and 5 (5%) survived to discharge. Survival rate for foals was 38% in Group CCS, and 90% in Group ECS. Under conditions similar to those in this study, it is calculated that caesarean section is preferable to CVD if dystocia is protracted and great difficulty and trauma is involved, even if CVD allows delivery of the foal.

This study was designed to evaluate the haemostatic suture as a means of preventing haemorrhage from the hysterotomy in mares after caesarean section. At 2 university hospitals 1982-1994, 48 mares had caesarean section for dystocia, 10 as an elective, and 8 mares concurrently with colic surgery. The haemostatic suture was used in 31 of 66 mares (47%) and surgery period was significantly (P<0.05) shorter when it was not applied. Anaemia (PCV<30%) was recorded in 13 (22%) of 58 mares, excluding the colic group, and the haemostatic suture did not after this proportion of mares that had anaemia. Anaemia was 5 times more probable following caesarean section than vaginal delivery, evidence that bleeding from the hysterotomy is a serious and common complication of caesarean section in mares. Severe uterine haemorrhage was recorded in 3 mares that had an haemostatic suture (10%) and in 2 mares that did not (6%). The latter two mares died of haemorrhage. The suture, therefore did not eliminate post operative anaemia and severe uterine haemorrhage. If omitted, the hysterotomy should be closed with a full thickness pattern that is sufficiently tight to compress vessels in the uterine wall.

A case-control study used data in the National Animal Poison Control Center database to characterize risk factors for gastrointestinal ulceration and acute renal failure subsequent to the acute ingestion of ibuprofen in the dog. For gastrointestinal ulceration (GIU) subsequent to ibuprofen ingestion, four factors differentiated the 116 cases from the 93 controls. Risk of GIU was lower for dogs where the time from ingestion to intervention was known as opposed to missing (adjusted odds ratio (aOR) = 0.12, p = 0.0001). Risk of GIU was also lower for the Labrador breed (aOR = 0.22, p = 0.004). Risk of GIU was higher for each unit of the logarithm of time to intervention (aOR = 2.63, p = 0.0002) and for the German Shepherd breed (aOR = 5.67, p = 0.14). For acute renal failure (ARF) subsequent to ibuprofen ingestion, two factors differentiated the 80 cases from the 64 controls. Risk of ARF was lower for dogs where the time from ingestion to intervention was known as opposed to missing (aOR = 0.15, p = 0.0001). Risk of ARF was higher for each unit of the logarithm of time to intervention (aOR = 2.16, p = 0.01). Although this study failed to describe a dose-response relationship, it appears that there are significant breed differences in susceptibility to GIU subsequent to ibuprofen exposure. Time to intervention was critical for both GIU and ARF outcomes. Dogs, particularly German Shepherds, ingesting even small amounts of ibuprofen, may need to be managed aggressively.

We used a previously described sensitive and specific ovine lentivirus (OLV) recombinant transmembrane (rTM) protein enzyme-linked immunosorbent assay (ELISA) to detect anti-OLV antibodies and define OLV infection in breeding ewes from nine US Meat Animal Research Center (MARC) flocks. We estimated the production impacts of dam rTM ELISA seropositivity on ewe and lamb productivity in the birth-to-weaning interval using production data from 1466 breeding ewes (of which 1242 actually lambed) and their 2452 lambs born in spring 1992 using several multiple linear and logistic regression models. By adjusting for lamb weaning age, gender, type of birth and rearing, birth difficulty, dam age, and flock, the component of ewe or lamb productivity related to ewe OLV infection alone was isolated. The rTM ELISA-negative ewes produced significantly more total weight of weaned lamb per ewe-lambing (3.84 kg) and per ewe ram-exposed (4.95 kg) compared to their OLV-positive flockmates. Negative ewes also weaned 0.11 more lambs per ewe-lambing and 0.09 more lambs per ewe ram-exposed, gave birth to 0.13 more lambs per ewe ram-exposed, and were more likely to lamb after breeding (odds ratio (OR) = 1.9) compared to equivalent OLV-positive ewes. Lambs reared by OLV-negative ewes weighed 0.15 kg more at birth, gained 8 g more per day through weaning, and weighed 0.59 kg more at 56-day weaning. Preweaning mortality was lower (OR = 0.8) among lambs born to OLV-negative compared to OLV-positive ewes, although this difference was not significant. Our results suggest that subclinical OLV infection has important detrimental effects on sheep production which occur in cumulative fashion from breeding through weaning and that OLV control efforts may be financially justified in some sheep flocks.

This study evaluated changes in respiratory function in dogs with experimentally induced laryngeal paralysis treated with either unilateral arytenoid lateralization or ventral ventriculocordectomy, and compared the effectiveness of these procedures. Evaluation consisted of clinical assessment and tidal breathing flow volume loop and upper airway resistance measurements. Carbon dioxide and doxapram hydrochloride were used as respiratory stimulants. Initially, all dogs improved clinically after corrective surgery. However, by the end of the study, laryngeal collapse had developed in 2 of 5 dogs corrected by ventral ventriculocordectomy. No statistical differences in upper airway mechanics testing were seen between the surgical procedures. With both groups combined, many measurements of upper airway obstruction improved after surgical correction. Based on this study, these surgical procedures yield comparable results, although additional studies are needed to evaluate both the cause of laryngeal collapse and the role of upper airway mechanics testing in the evaluation of canine laryngeal paralysis.

The prevalence of and risk factors for ovine lentivirus (OLV) infection in 1466 breeding ewes in nine US Meat Animal Research Center (MARC) flocks were determined using a recombinant transmembrane protein (PTM) enzyme-linked immunosorbent assay (ELISA) to detect serum anti-OLV antibodies and define infection. Based on multivariable logistic regression, confinement birth and rearing (odds ratio (OR) = 1.6), older weaning ages (OR = 1.1 week-1), and older age (OR = 1.3-2.5 year-1 beyond age 1 year) were significantly associated with higher OLV prevalence in ewes. Prevalence also varied significantly by flock, with Finnsheep and Texel ewes having the highest prevalences and Booroola Merino and Suffolk ewes having the lowest prevalences. These findings support the hypothesis that management control efforts should concentrate on events early in the life of sheep, as this period is associated with factors which can modulate the risk for OLV infection.

The purposes of this study were to develop an experimental model of canine laryngeal paralysis that mimicked the naturally occurring disease and to document the upper airway changes produced, both clinically and with pulmonary function testing. Ten dogs had bilateral recurrent laryngeal neurectomy performed and were recovered from anesthesia. Tidal breathing flow-volume loop analysis and upper airway resistance measurements were taken before and after the development of clinical laryngeal paralysis while dogs breathed room air and after the individual administration of 2 respiratory stimulants. Clinical signs of laryngeal paralysis developed 38 days (median) following denervation. Although some variations were present, tidal breathing flow-volume loop analyses on room air, following denervation, were similar to those reported in naturally occurring cases. Upper airway resistance increased following denervation and was significantly increased with both respiratory stimulants. We concluded that bilateral recurrent laryngeal neurectomy resulted in clinical signs and respiratory changes similar to those of idiopathic canine laryngeal paralysis.

The modified card agglutination test (MCAT) was used to detect antibodies to Anaplasma marginale in 4994 samples collected from market cattle through the Brucellosis Eradication Program in Illinois. The MCAT reactor rate in the sample was 6.4%. The statewide prevalence estimate increased to between 7.1% and 10.7% when corrected for sampling distribution and test sensitivity and specificity. While the sample reactor rate measures the proportion of infected cattle moving through the market system and into new herds, consideration of the sampling proportions and test characteristics is important when estimating the overall prevalence. Cows were found to be at decreased risk relative to male cattle in lower-prevalence areas, but the risk was similar in higher-prevalence areas. In both higher- and lower-prevalence areas, the risk for seropositivity increased from 1 year of age onwards, but the rate of increase with age was greater in the higher-prevalence areas. Calves, however, had higher seroprevalence levels than 1-2-year-old animals. The risk was highest for Angus and Angus-Hereford cross cattle, while dairy cattle showed a decreased risk in the whole sample, but not when the analyses were stratified by prevalence level. There was a higher concentration of dairy cattle in areas with lower prevalence levels.

Factors associated with preweaning mortality in lambs were identified by developing risk profiles with logistic regressions for perinatal and postnatal mortality. Compared with heavy lambs, lambs of low birth weight had almost twice the risk of perinatal mortality (odds ratio [OR] = 1.9) and lambs of average weight had a slightly lower risk (OR = 0.7). Two of four lambing location categories affected perinatal mortality, with lambs born at unmonitored areas at greatest risk (OR = 2.7). Multiple births increased the risk of perinatal mortality (OR = 1.5), especially among Targhee lambs (OR = 4.0). Breed variations in perinatal mortality were significant in Suffolk lambs (OR = 1.9) and Booroola Rambouillet lambs (OR = 2.1). Lambs born weak had an increased risk of postnatal mortality while strong lambs had a decreased risk (OR = 3.7 and 0.6, respectively) if the dam had an adequate milk supply. Poor milk supply increased the risk of postnatal mortality for lambs of average vigour (OR = 3.3), but did not change the risk for weak or strong lambs. Male lambs castrated at 30 days of age were at less risk of postnatal mortality (OR = 0.3) than females. There were slight increases in the risk of postnatal mortality for intact males (OR = 1.3), low birth weight lambs (OR = 1.6), and lambs born in sheds (OR = 1.3). Suffolk lambs (OR = 1.8) and Targhee lambs (OR = 1.6) had a higher risk of postweaning mortality.

An enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies against ovine lentivirus (OLV) in serum, colostrum, and milk from naturally infected sheep. The assay used OLV recombinant transmembrane envelope protein (rTM) as a test antigen. Matched serum/colostrum and serum/milk samples were collected at 24h, 4 weeks (mid-lactation), and 8 weeks (weaning) post-lambing. Among 129 paired samples collected at 24 h post-lambing, there was overall test agreement (concordance) of 82.9% and a kappa value of 0.658 between serum and colostrum rTM ELISA results. Among 130 mid-lactation samples, the milk ELISA had 100% specificity and 64.9% sensitivity relative to the serum ELISA, there was concordance of 79.2%, and a kappa value of 0.602. At mid-lactation, the serum agar gel immunodiffusion test had a sensitivity of 0.390 and 0.560 relative to the serum and milk rTM ELISAs, respectively. Matched serum and milk rTM ELISA results at weaning were very similar to those at mid-lactation. Finally, increased occurrence and severity of subclinical mastitis at weaning was found in ELISA-seropositive compared with ELISA-seronegative ewes. Both subclinical mastitis and ewe OLV infection had a negative impact on lamb growth and weaning weights. Compared with blood, colostrum and milk are easier and less expensive to sample and store. These results suggest that rTM ELISA testing of colostrum and milk could be used to supplement serologic testing in OLV screening or eradication programs.

The bioequivalence of Strongid C and generic pyrantel tartrate was determined in a controlled study using 30 horses with naturally acquired endoparasitic infections. Three horses were randomly allocated to each of ten replicates based on quantitative nematode and ascarid egg counts and fecal larvae culture results. Horses within each replicate were randomly assigned to one of three treatment groups. Horses in Treatment Group 1 received only oats; horses in Treatment Group 2 received generic pyrantel tartrate pellets (2.65 mg pyrantel tartrate kg-1) mixed with oats; horses in Treatment Group 3 were fed Strongid C pellets (2.65 mg pyrantel tartrate kg-1) mixed with oats. Horses were treated daily for a 30 day continuous treatment period. At the termination of the study the horses were necropsied and endoparasites recovered, identified, and enumerated. In all instances, no significant difference (P > 0.05) in mean numbers of parasites recovered existed between horses treated with generic pyrantel tartrate and Strongid C. Numbers of gastrointestinal parasites recovered from horses treated with generic pyrantel tartrate or Strongid C were shown to be significantly different (P < 0.05) from numbers of gastrointestinal parasites recovered from non-treated controls for the large strongyles (Strongylus vulgaris, S. edentatus, and Triodontophorus spp.), small strongyles (Cyathostomum spp., Cylicocyclus spp., and Cylicostephanus spp.) and fourth-stage Parascaris equorum. Numbers of adult P. equorum recovered from horses treated with Strongid C were also significantly different (P < 0.05) from those from non-treated controls. Numbers of adult P. equorum recovered from horses treated with generic pyrantel tartrate were not significantly different (P = 0.0761) from those from non-treated controls. The determination of bioequivalence was based upon the 95% confidence interval of the difference between the mean number of parasites recovered from horses treated with generic pyrantel tartrate and the mean number of parasites recovered from horses treated with Strongid C. For all instances in which the numbers of parasites recovered from horses treated with either Strongid C or generic pyrantel tartrate were significantly different from the numbers of parasites recovered from non-treated controls, bioequivalence was demonstrated.

Risk factors for development of pleuropneumonia were determined by reviewing medical records of 45 horses with pleuropneumonia and 180 control horses examined between Jan 1, 1980 and Jan 1, 1990. Factors considered included age, breed, sex, occupation, transport farther than 500 miles within the previous week, racing within the previous 48 hours, viral respiratory tract infection or exposure to horses with viral respiratory tract disease within the previous 2 weeks, and vaccination against influenza or rhinopneumonitis within the previous 6 months. Results indicated that Thoroughbreds were at a greater risk of developing pleuropneumonia than were other horses, and Standardbreds were at a reduced risk. Transport farther than 500 miles and viral respiratory tract disease or exposure to horses with respiratory tract disease were determined to be risk factors for the development of pleuropneumonia.

Dermatitis consisting of blisters on the nose and other parts of the body was reported among horses at a Midwestern horse show. Some horses also had jaundice, hematuria and anorexia. An outbreak investigation was initiated, and of 239 horses for which information could be obtained, 58 (24%) were found to have been affected. Median duration of illness was 5 days, and all horses recovered. Age, sex, water source, grain source, and stabling location were not associated with illness. The use of wood shavings bedding obtained at the show grounds was the factor most strongly associated with the development of vesicular lesions. Horses that became ill were 43 times more likely to have been bedded on wood shavings obtained from the show grounds than were horses that did not become ill. Among horses bedded on shavings from the show grounds, the risk was further increased by a factor of 5 if the shavings had been wetted. Neither organic nor heavy metal toxicants were identified in the samples of the wood shavings. However, samples did contain plant tissues originating from a tree belonging to the family Simaroubaceae, some species of which are known to cause vesicular eruptions in people.

The database of the National Animal Poison Control Center (NAPCC) was evaluated as a source for animal poison data indicating human health hazards in indoor and outdoor environments. From 14,150 calls in the 1985 database, 259 cases were identified with histories suggesting human exposure. A subgroup of 25 cases with known human exposure was found. Dogs were the most common sentinel animal, but bird cases represented the highest proportional selection from the total 1985 call list. Indoor exposures represented 43.2% of cases; the most common toxicants were insecticides, lead and toxic fumes. Exposures associated with lawns were mainly due to insecticides and herbicides and constituted 25.5% of cases. Other outdoor exposures composed the remaining 31.7% of cases, with insecticides, herbicides and unidentified toxins the leading categories. Many of the specific agents identified, such as organophosphate insecticides, lead, gas and fume toxins, and phenoxy herbicides are also risk factors in human diseases. This study indicates that databases such as NAPCC could serve as sources of sentinel animal intoxications for followup studies to evaluate known and potential human health hazards.