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Biomedical subjects

W D Hueston

Publications and source records attributed to W D Hueston.

35 records · Page 2Linked to original sources
PubMed1990

Isolation of Mycobacterium paratuberculosis from washed bovine ova after in vitro exposure.

To establish whether Mycobacterium paratuberculosis could be cultured from Dulbecco phosphate-buffered saline solution (DPBSS) and to test 3 sampling methods, DPBSS supplemented with 2% fetal bovine serum was inoculated with M paratuberculosis at concentrations of 10(4), 10(3), 10(2), 10(1), and 10(0) colony-forming units/ml. The inoculated media was sampled after mixing, after centrifugation, and after centrifugation and decontamination with 0.75% hexadecylpyridinium chloride. The samples were inoculated onto 3 slants of Herrolds egg yolk medium supplemented with sodium pyruvate and mycobactin J and 1 slant without mycobactin J. Mycobacterium paratuberculosis was isolated following all 3 sampling methods for all concentrations. Treatment with hexadecylpyridinium chloride decreased the number of colonies isolated. To test the efficacy of a 10-step wash procedure for removing M paratuberculosis from bovine ova, washed zona pellucida intact bovine ova were incubated in DPBSS supplemented with 2% fetal bovine serum containing concentrations of 10(4), 10(3), 10(2), 10(1), and 10(0) colony-forming units of M paratuberculosis/ml for 12 hours at 22 C. Ten zona pellucida intact ova were removed from each concentration and washed by passing through 10 changes of DPBSS supplemented with 15% fetal bovine serum. The media from each wash step was inoculated onto slants of Herrolds egg yolk medium. The ova were included with the tenth wash step. Mycobacterium paratuberculosis was isolated from 1 of 10 tenth-wash steps at the 10(4) concentration and 5 of 10 tenth-wash steps at 10(3).

Animals↗
PubMed1989

Patterns of ionizing radiation exposure among women veterinarians.

Radiation detection devices (film badges) were distributed to a random sample of 118 women in Ohio, Indiana, and Michigan, who had graduated from a US veterinary school between 1970 and 1980, inclusive. Ionizing radiation exposure exceeded 15 mrem/mo in 17% of the women monitored. The maximal recorded whole-body dose was 44.2 mrem/quarter-year, which was well below the maximal permissible doses of 1,250 mrem/quarter-year for nonpregnant women and 500 mrem/quarter-year for pregnant women. Associations between the women's safety beliefs or behaviors and recorded exposure were not observed; however, the school from which the women graduated was an important determinant of safety behavior.

Environmental Exposure↗
PubMed1989

Intramammary antibiotic treatment at the end of lactation for prophylaxis and treatment of intramammary infections in ewes.

Ewes treated by intramammary infusion of cephapirin benzathine at the end of lactation were less likely to develop new intramammary infections by early in the next lactation. A controlled clinical trial involving 135 treated ewes and 145 untreated control ewes evaluated the prophylactic and treatment efficacy of intramammary antibiotic treatment of ewes at the time of weaning lambs. Milk samples for bacteriologic examination and identification of intramammary infections were collected at weaning of lambs and 1 to 3 weeks into the subsequent lactation. Untreated ewes were 2.6 times more likely than treated ewes to develop new intramammary infections between sampling times. Existence of an intramammary infection in one mammary gland significantly increased the risk of the other mammary gland becoming infected. Treatment also appeared to be associated with a higher cure rate of existing infections.

Animals↗
PubMed1989

Evaluation of radiation safety in 29 central Ohio veterinary practices.

A sample of 29 veterinary practices in Central Ohio were visited to assess radiation safety practices and observance of state regulations. Lead aprons and gloves were usually available, but gloves were not always worn. Protective thyroid collars and lead glasses were not available in any practice, lead shields in only five practices, and lead-lined walls and doors in only two practices. Eighteen practices had none of the required safety notices posted.

Equipment Safety↗
PubMed1989

Bacterial counts in bedding materials used on nine commercial dairies.

Bacterial counts were monitored for 1 yr in bedding materials used on nine commercial dairies. Organic materials used to bed lactating cows had significantly higher moisture content and gram-negative bacterial, coliform, Klebsiella species, and streptococcal counts than did inorganic materials. Klebsiella species counts were higher in sawdust than in chopped straw. Streptococcal counts were higher in chopped straw than sawdust. Bacterial counts did not differ between sand and crushed limestone. Gram-negative bacterial and coliform counts were higher during summer and fall than in winter and spring months. Streptococcal counts did not differ among seasons of the year. Linear relationships were significant between total rates of clinical mastitis during lactation and both gram-negative bacterial and Klebsiella species counts in lactating cow bedding. These data indicate that bacterial populations differed between both types of bedding and among seasons of the year. Rates of clinical mastitis were related to bacterial counts in bedding.

Animals↗
PubMed1989

Field survey of clinical mastitis in low somatic cell count herds.

Nine commercial dairy herds, each with low herd milk somatic cell counts, were monitored for 1 yr to determine prevalence of intramammary infections and rates of clinical mastitis. Staphylococcus species was the bacterial group most frequently isolated from quarters at calving and at drying off. Environmental streptococci and coliform intramammary infections totaled less than 6% of quarters at both calving and at drying off. Staphylococcus aureus were isolated from less than 1% of quarters and Streptococcus agalactiae from 0% of quarters at both calving and drying off. A total of 646 clinical cases of mastitis were diagnosed in 548 quarters of 406 cows. Mean rate of clinical mastitis among herds was .457 clinical cases/305 cow-days. Rates of clinical mastitis ranged among herds from .273 to .748 clinical cases/305 cow-days. Coliforms and bacteriologically negative and environmental streptococci accounted for 82.3% of clinical cases. Rates of clinical mastitis and severity of clinical signs differed among herds, seasons of the year, parity groups, and stages of lactation. Rates of clinical mastitis were highest during summer, in first lactation cows, and during the first 7 d of lactation.

Animals↗
PubMed1988

Estimation of the costs of mastitis, using National Animal Health Monitoring System and milk somatic cell count data.

Data collected by the National Animal Health Monitoring System in Ohio for a 12-month period during 1986 and 1987 were used to determine the relative magnitude of costs associated with mastitis in the following categories: milk production loss, veterinary services, drugs, producer labor, and "other" factors. The cost of milk loss associated with mastitis that was reported by producers cooperating in the National Animal Health Monitoring System program was compared with estimates based on bulk tank somatic cell counts and individual cow milk somatic cell counts. Using producer-reported estimates, milk loss accounted for about one third of the total cost associated with mastitis. When estimates of milk loss were replaced by estimates based on bulk tank somatic cell counts, milk loss accounted for over 80% of the total cost of mastitis. Estimates of the cost of milk loss based on studies relating milk yield to somatic cell counts differed considerably. Consequently, it was unclear how to best estimate the relative magnitude of the milk loss component of mastitis costs.

Animals↗
PubMed1988

Scrotal circumference measurements on young Holstein bulls.

Scrotal circumference was measured on all young Holstein bulls entering an artificial insemination center over a 57-month period. A total of 3,008 measurements were taken on 723 bulls between the ages of 5 and 18 months. Mean scrotal circumference, standard deviation, and 10th and 25th percentile statistics were calculated for each one-month interval between 5 and 18 months of age. Scrotal circumference increased as a logarithmic function of age and was best described by a quadratic regression equation. This information provides the veterinary practitioner with indices for normal scrotal circumference measurements for young Holstein bulls, and an estimate of the scrotal circumference growth curve.

Age Factors↗
PubMed1988

Evaluating risk factors in disease outbreaks.

The investigation of disease outbreaks in herds and flocks includes the gathering of multiple types of discrete data on the characteristics of the disease and the potential risk factors involving agent, host, and environment. Descriptive statistics such as rates, ratios, and proportions offer the investigator tools for counting the disease occurrence, for communicating the results of the investigation to others, and for further analyzing the patterns of disease in order to identify the true risk factors. Because there are several alternative methods for calculating descriptive statistics, specific definitions of each statistic should be followed so that ambiguity and misinformation are avoided. The practitioner must choose one definition and apply it consistently in disease investigations. Consistency allows for comparison of descriptive statistics from one investigation to another, or from one time to another time within the same herd. Analytic statistics allow for a critical evaluation of the data represented in rates, ratios, and proportions. Statistical tests address the all-important question, "Could these observed associations between disease and potential risk factors have occurred by chance alone?" This question must be addressed so that the wisest intervention decisions can be made. The tools described in this article are useful in routine herd health practice situations as well as the investigation of disease outbreaks and impaired productivity. Descriptive statistics provide a system for counting disease so that the practitioner can evaluate progress in the individual herd. The ability of the practitioner to quantify changes in disease occurrence in the herd provides hard evidence for the producer of the impact of herd health approaches.

Animals↗
PubMed1988

Use of dairy herd improvement somatic cell information by Ohio dairy producers and their perceptions of mastitis.

A telephone survey was conducted of 149 current recipients of the Ohio DHIA SCC option, 30 past recipients of the SCC option, and 30 producers who had never received the SCC option. Producers were questioned to ascertain their knowledge of mastitis, how they used SCC information, their treatment and prevention of mastitis, and their use of veterinary services. Producers' perceptions of mastitis indicated a high awareness of the consequences of mastitis. However, 10% of producers on DHI still did not practice postmilking teat dipping, and 16% did not handle mastitic cows any differently during milking. Current recipients of SCC data used the data more frequently than did past recipients of the SCC data to evaluate mastitis treatment or control, choose cows to cull, identify cows to dry off early, indicate herd infection, and evaluate mastitis control. The major reason given by nonrecipients for never having enrolled in the SCC program was that they did not perceive a need for it. Further educational programs explaining SCC and its use to producers seems warranted.

Animal Husbandry↗
PubMed1986

Serratia liquefaciens mastitis in a dairy herd.

Serratia liquefaciens mastitis was detected and investigated in a 41-cow Holstein herd. Twenty cows were treated for mastitis over a 3-month period. Serratia liquefaciens was isolated from milk samples obtained from 8 of 12 cows tested during the epizootic. Results of an epidemiologic investigation suggested that extensive frostbite of the teats decreased the udder defense. Poor milking technique and hygiene were responsible for increased exposure of the damaged teats to potential udder pathogens. Treatment of each cow resulted in initial clinical improvement, but exacerbations occurred in 75% of the cows with documented S liquefaciens infections.

Animals↗
PubMed1986

Detection of ovine intramammary infection with the California mastitis test.

The overall sensitivity of the California mastitis test (CMT) for detecting intramammary infection (the likelihood of a positive CMT score in the presence of intramammary infection) was 69.3%. The specificity of the CMT (likelihood of a negative test in the absence of intramammary infection) was 76.5%. When only infections by major ovine mastitis pathogens were considered, the sensitivity increased to 100% and the specificity decreased to 71.1%. Bacterial cultural examination and CMT scores were recorded for 526 samples of milk obtained from 106 brood ewes. Positive CMT scores were recorded for all samples from udder halves infected with major ovine mastitis pathogens (coagulase-positive staphylococci, Escherichia coli, and Pasteurella haemolytica). The CMT scores for samples from udder halves infected with coagulase-negative staphylococci were variable.

Animals↗
PubMed1986

Patterns of nonclinical intramammary infection in a ewe flock.

Coagulase-negative staphylococci were the most frequent bacterial isolates from nonclinical intramammary infections (NIMI) in a ewe flock. The prevalence of NIMI was 22.9% of the udder halves at lambing and decreased to 12.5% or less between week 2 and week 6 of lactation. The decrease was due mainly to the elimination of infections involving coagulase-negative staphylococci. The frequency of new NIMI in the first 6 weeks of lactation was less than 1% of the noninfected udder halves per week. The prevalence of NIMI increased steadily from 16.1% of the udder halves at the time of weaning the lambs to 29% at postweaning week 3. The new infection rate averaged 9.7% per week during the postweaning 3 weeks. The principal bacterial isolate in the new NIMI was coagulase-negative staphylococcus. Nonclinical intramammary infection in a ewe flock was monitored by bacteriologic cultural examinations of milk samples obtained from both udder halves of 24 ewes during early lactation and of 31 ewes in the same flock during the early postweaning period. The patterns of NIMI were similar to the patterns reported in cattle.

Animals↗
PubMed1986

Epidemiologic considerations in reporting herd somatic cell counts.

The reporting of herd summaries of individual cow somatic cell counts differs between the nine Dairy Records Processing Centers. The objectives of this paper are to review the present reporting; to compare the methods used to calculate herd somatic cell counts; and to discuss the epidemiologic implications of these methods. Estimates of central tendency and frequency distributions are the most commonly used herd summary statistics for somatic cell counts. Analyses of the frequency distributions are less widely available. Potential uses of herd somatic cell counts are to measure one aspect of herd milk quality; to estimate the prevalence of mastitis; to analyze mastitis patterns within the herd; and to investigate new areas for mastitis control research. Presently, the best available methods for these applications appear to be bulk tank somatic cell counts or weighted arithmetic means for gauging milk quality; frequency distributions for estimating mastitis prevalence; analyses of frequency distributions of mean linear score by lactation and stage of lactation for identifying mastitis patterns within a herd; and frequency distributions or estimated incidence rates, adjusted for differences in age and stage of lactation, for investigating new areas for mastitis control research.

Animal Husbandry↗
PubMedDate not supplied

Risk factors associated with early respiratory disease complex in broiler chickens.

Early respiratory disease complex (ERDC) is a term coined to describe an acute disease characterized by depression, respiratory distress, and increased mortality in 2-to-3-wk-old broiler chickens. Postmortem lesions include airsacculitis, fibrinous pericarditis, and perihepatitis. Colisepticemia is the primary cause of death. In order to investigate the association between ERDC and farm management factors, a retrospective case-control study was conducted by collecting data covering a 6-mo period (January-June 1997) from four broiler integrators on the Delmarva peninsula. Univariate and multivariate statistical analyses revealed that flock size was positively associated (P = 0.02) and layout time was negatively associated (P = 0.05) with ERDC.

Acute Disease↗