Biomedical subjects

D W Hird

Publications and source records attributed to D W Hird.

At least 37 records · Page 2Linked to original sources

PubMed1995

Genotypic and phenotypic analysis of Salmonella strains associated with an outbreak of equine neonatal salmonellosis.

Isolates of Salmonella choleraesuis serotype ohio (S. ohio) recovered during an outbreak of equine neonatal salmonellosis on a Thoroughbred farm were compared with isolates of the same serotype from various animal, feed and environmental sources. Biochemical profiles, antimicrobial susceptibility patterns, phage susceptibility, plasmid profiles, restriction endonuclease analysis and ribotyping were used to compare relatedness of the strains. A total of 46 outbreak and non-outbreak associated isolates of S. ohio were studied. Differences in antimicrobial susceptibility patterns, phage susceptibility and plasmid profiles were useful for differentiating outbreak isolates from other equine isolates as well as bovine, porcine and some poultry isolates. Feed and other poultry isolates, most in geographic proximity to the outbreak, were indistinguishable from outbreak isolates by any of the methods employed. Investigative studies on the farm along with results of genotypic and phenotypic analysis of isolates suggested that contaminated feed was the most likely source of Salmonella in this outbreak.

Animals↗

PubMed1995

Infection of cattle with bluetongue viruses in Queensland, Australia: results of a sentinel herd study, 1990-1992.

Between 1990 and 1992, 47 sentinel herds of 10-20 cattle each were established throughout Queensland, Australia to monitor bluetongue virus infection. Sixteen herds at 12 locations seroconverted to bluetongue viruses during the study. Herd incidence rates ranged from 0.0 to 3.45 seroconversions per cattle-year at risk. The mean incidence rate was 0.29 seroconversions per cattle-year at risk (95% confidence interval 0.23-0.36), and the median incidence rate was 0.32 seroconversions per cattle-year at risk (95% CI 0.0-0.54). Only seroconversions to bluetongue virus serotypes 1 and/or 21 were detected in the study; no evidence was found of infection with other serotyped previously isolated in Australia (3, 9, 15, 16, 20, 23). Seroconversion to serotype 1 occurred more frequently than seroconversion to serotype 21. Seroconversion generally occurred between April and July, being most common in May, but varied considerably within each of the 3 years of the study. This study confirmed the presence of only serotypes 1 and 21 in Queensland and demonstrated the sporadic and restricted nature of bluetongue virus infection in the Queensland cattle herd.

Animals↗

PubMed1994

Effects of and factors associated with umbilical hernias in a swine herd.

Of 2,958 pigs from a 320-sow, farrow-to-finish herd that were evaluated from birth to slaughter, 44 (1.5%) developed umbilical hernias. Hernias were detected mostly (34/44) when the pigs were between 9 and 14 weeks of age and were not fatal despite lack of treatment. Among littermates, weight gain prior to weaning was significantly (P = 0.04) lower in pigs that developed hernias (144.7 g/d) by 30 weeks of age than for nonaffected pigs (163.3 g/d), but growth rates from weaning to about 45 kg did not differ significantly. Records of pigs sired by 13 purebred boars were used to evaluate breed-of-sire associations. Pigs sired by American Spotted (n = 19; relative risk [RR] = 8.3; 95% confidence interval [CI] = 2.1 to 32.7) and Duroc boars (n = 378; RR = 2.1; 95% CI = 1.0 to 4.5) were more likely to develop umbilical hernias than were pigs (n = 1,644) sired by Yorkshire boars. Umbilical lesions (omphalitis or umbilical abscess) were associated (RR = 7.6; 95% CI = 1.2 to 49.5) with umbilical herniation on an individual basis, but the association was not evident (RR = 1.2; 95% CI = 0.2 to 7.6) when the litter was the unit of analysis. Analysis of sire associations, stratified by umbilical lesion status, indicated increased risks in the nonlesioned stratum for the American Spotted (RR = 8.7) and Duroc sires (RR = 2.2). Adequate comparisons of sire breed in the lesioned stratum could not be made, because umbilical lesions were an infrequent finding (9/2, 958).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Risk factors for development of foot abscess in neonatal pigs.

Factors associated with foot abscess were evaluated in a cohort of 3,322 suckling pigs reared on a woven-wire floor (wire diameter, 0.5 cm; size of openings, 1 x 3.8 cm). In bivariate analysis, foot abscess was significantly (P < 0.05) associated with postpartum sow illness, number of pigs born alive, and parity, but not with birthweight (P = 0.31) or time spent on wire flooring (P = 0.89). One oxytetracycline treatment (100 mg, IM) at birth or 1 treatment at birth and a second 5 to 7 days later reduced (P < 0.05) the risk of lesions by about half. Multivariate analyses indicated that pigs in large litters (> 10 pigs at birth) born to sows with postpartum illnesses had an increased risk (relative risk [RR], 3.77) of developing foot abscess, compared with pigs in small litters (< or = 10 pigs) born to unaffected sows. For sows without evidence of postpartum illness, pigs in large litters had a slightly increased risk (RR, 1.32) of developing foot abscess, compared with pigs in small litters. Pigs born to multiparous sows also had an increased risk (RR, 1.69) of developing foot abscess, compared with pigs born to primiparous sows. Similar risk estimates were obtained when logistic regression models included location farrowed (crate number) as a fixed effect, and when litter was a random effect in a logistic-binomial regression.

Abscess↗

PubMed1994

Comparison of particle concentration fluorescence immunoassay to card and complement fixation tests using isolation of Brucella abortus as the standard.

Serologic test data and bacteriologic culture results from 816 cattle were evaluated. Brucella abortus (field strain or strain 19) was isolated from 27.3% of the cows. Results of the card test, particle concentration fluorescence immunoassay (PCFIA), and complement fixation (CF) test were compared. Antibody titers were directly associated with B. abortus isolation, with the majority (64.7%) of field strain isolations having a PCFIA value of < or = 0.300 and a CF test result of at least 1+ at a 1:160 dilution. The specificity of the CF test was significantly higher than that of the PCFIA (at CF > or = 1:40 and PCFIA < or = 0.300).

Agglutination Tests↗

PubMed1993

Congenital abnormalities in immature dogs from a pet store: 253 cases (1987-1988).

In a pet store, 6- to 18-week-old dogs were examined for congenital abnormalities. Of those pups offered for sale over a 2-year period (1987 and 1988), 15% (253/1,679) had at least 1 congenital defect, and 1.5% (26/1,679) had multiple congenital abnormalities. Defects observed and their respective rates were patellar luxation, 7.2% (121/1,679); cardiac abnormalities characterized by murmurs, 0.7% (11/1,679); palpebral abnormalities, 3.0% (50/1,679); inguinal hernia, 1.3% (22/1,679); umbilical hernia, 0.6% (10/1,679); faciodental malformations, 1.3% (21/1,679); and cryptorchidism, 2.6% (44/1,679). Rates of congenital abnormalities in pups from this study were higher than published rates in adult dogs.

Animals↗

PubMed1993

Epidemiology of cercopithecine herpesvirus 1 (B virus) infection and shedding in a large breeding cohort of rhesus macaques.

The epidemiology of B virus infection in a large (n = 157) cohort of rhesus macaques at the California Regional Primate Research Center was evaluated prospectively from September 1989 through January 1991 by serial physical examinations, a behavioral substudy (n = 51), and repeated diagnostic testing. Half were B virus antibody-positive at baseline; subsequently, incident cases of infection were documented through serology alone (42) or with virus isolation (5). Eight recurrent infections and a single symptomatic (primary) case were observed. Risk of B virus infection increased as monkeys aged, with few > 3 years old remaining uninfected. Postpubertal monkeys and those entering sexual adolescence (2-3 years) were at greatest risk, although wounding by cagemates and breeding history (for females) were both significant predictors of time to infection. B virus was isolated from oral or conjunctival and genital tissues in equal proportions. Transmission occurred only during the breeding season, possibly coinciding with an elevation in social stressors in the population.

Animals↗

PubMed1993

Prevalence and risk factors for iron deficiency anemia in weanling rhesus macaques.

Standard epidemiologic methods were used to determine the prevalence and risk factors for iron deficiency at weaning in 143 weanling rhesus macaques (Macaca mulatta) raised indoors at the California Primate Research Center, Davis, CA. Maternal, infant, and management factors were investigated. Prevalence of iron deficiency anemia was 19%, as defined by mean corpuscular volume less than or equal to 66 femtoliters. It was found that animals raised entirely or partially in the nursery had less iron deficiency than dam-reared offspring. Results also suggest multiparous dams were more likely to have iron-deficient weanlings than primiparous dams. These results were discussed in relation to human and nonhuman primate pediatric medicine.

Anemia, Hypochromic↗

PubMed1992

Morbidity and mortality in pups from pet stores and private sources: 968 cases (1987-1988).

Morbidity (greater than or equal to 1 disease condition) for pups sold from 3 pet stores from January 1987 through December 1988 ranged from 54 to 68%. In 1 store, morbidity was higher for store pups, compared with pups originating from private parties, for such disease conditions as "kennel cough," diarrhea, and several species of gastrointestinal parasites. In-store mortality ranged from 5 to 9.5% of pups arriving for sale.

Animals↗

PubMed1992

Serologic and bacteriologic test results after adult vaccination with strain 19 in three dairy herds infected with brucellosis.

Milk culture data and serologic test results were evaluated after adult vaccination with Brucella abortus strain 19 in cattle of 3 large California dairy herds infected with brucellosis. Strain-19 organisms were isolated by culture of milk from 1.9% of the vaccinated cows. Isolation of field strain of B abortus varied directly with magnitude of complement-fixation (CF) and rivanol titers. At time of milk culture, 74% of cows from which field strain was isolated had CF titer greater than or equal to 160, compared with 58% of cows from which strain 19 was isolated. Cows with CF titer greater than or equal to 160 at 2 months or greater than or equal to 80 to 4 months after adult vaccination were more likely to be correctly classified as reactors (on the basis of subsequent milk culture results and/or persistently high serologic titer) than were cows with lower CF titer at these times. Cows from which B abortus strain 19 was isolated from milk were more likely to maintain persistent serologic titer than were cows from which neither strain of B abortus was isolated.

Animals↗

PubMed1992

Diarrhea rates and risk factors for developing chronic diarrhea in infant and juvenile rhesus monkeys.

Ten independent risk factors were evaluated in an effort to identify predictors of problem diarrhea at weaning and chronic diarrhea in infant and juvenile rhesus monkeys (Macaca mulatta) at the California Primate Research Center. None of the variables proved to be a significant predictor of problem diarrhea at weaning; however, two of the variables were significant predictors for developing chronic diarrhea. Odds ratios, adjusted for other variables in the logistic regression model, showed that compared with females, males were nearly three times more likely to develop chronic diarrhea, and nursery-reared animals were 7.5 times more likely to develop chronic diarrhea than were breast-fed animals. The annual incidence rates for problem diarrhea at weaning for 1978, 1979, and 1980 were 49%, 37%, and 41%, respectively. A weighted average annual incidence rate for problem diarrhea at weaning for the 3-year period was 39%. The incidence rate for chronic diarrhea for the 3-year period was 49%.

Animals↗

PubMed1991

Chagas' disease: risk factors for house infestation by Triatoma dimidiata, the major vector of Trypanosoma cruzi in Costa Rica.

The reduction of domiciliary infestation by insect vectors, the key to controlling Chagas' disease, depends on identification of housing features associated with infestation. In this study, log-linear modeling was used to reanalyze data collected in 1964-1968 from 371 houses on characteristics potentially associated with infestation by the vector Triatoma dimidiata in a Costa Rican town with endemic Chagas' disease. A possible increased risk of infestation was observed for houses with a dirt floor (as compared with houses with another floor type) and for houses in poor sanitary condition (as compared with houses in good sanitary condition). A new risk factor for house infestation, the presence of roof tiles, was identified; the odds of infestation for houses with a tile roof were 2.4 times greater than the odds for houses with a galvanized metal roof. This significantly increased risk is probably due to the harboring of T. dimidiata in stacks of spare tiles next to house walls rather than to the tile roofs themselves.

Chagas Disease↗

PubMed1991

Expenditures for veterinary services and other costs of disease and disease prevention in 57 California beef herds in the National Animal Health Monitoring System (1988-1989).

Data on costs associated with episodes of disease and disease prevention, including expenditures for veterinary services, were collected from 57 California beef cow-calf herds during 1988-1989 as part of the National Animal Health Monitoring System. Mean cost associated with episodes of disease was $33.90/cow-year, with $0.78 and $1.37/cow-year being spent for veterinary services and drugs, respectively. The highest cost for veterinary services related to episodes of disease were for dystocia, lameness, and ocular carcinoma. For disease prevention, mean expenditures for veterinary services were $1.67/cow-year, nearly all of which was spent on prevention of reproductive tract conditions. Preventive expenditures for veterinary services related to female infertility (pregnancy examination), vaccination against brucellosis and male infertility (breeding soundness examination) were $0.72, $0.39, and $0.22/cow-year, respectively. Many costs associated with episodes of disease and disease prevention were similar to those reported from Colorado National Animal Health Monitoring System beef herds.

Agriculture↗

PubMed1991

An outbreak of equine neonatal salmonellosis.

An outbreak of salmonellosis in foals occurred on a large Thoroughbred farm in California. Only foals less than 8 days of age exhibited clinical signs, which included depression, anorexia, and diarrhea. Three foals died from septicemia. The agent responsible was Salmonella ohio, which is rarely involved in salmonellosis in horses. During the course of the outbreak, S. ohio was isolated from 27 of 97 mares (27.8%) and 34 of 97 foals (35.1%). Mares were the presumed source of infection for foals. The absence of clinical signs in mares allowed for increased exposure of foals through environmental contamination. Although foals continued to become infected after strict control measures were adopted, none became ill. Salmonella serotypes of seemingly low virulence can produce serious disease outbreaks.

Animals↗

PubMed1991

Patterns of bovine dairy submissions to the California Veterinary Diagnostic Laboratory System.

Dairy cattle submissions to the California Veterinary Diagnostic Laboratory System (CVDLS) were analyzed to determine submitter statistics. Eligible submissions were those received July 1, 1987 through December 31, 1989 for reasons other than regulatory brucellosis serology. A comprehensive list frame of California dairies was constructed from Brucella Ring Test information and served as the comparison population for the study. Analyses were performed based on geographic location, herd size, proximity to a CVDLS laboratory, and frequency of submission. Thirty-nine percent of the 2,490 California dairies in the reference population had submitted specimens greater than or equal to 1 time to the CVDLS during the study period. Twenty-three percent of the reference population had submitted greater than or equal to 2 times. Specimens were more likely to be submitted from larger herds than smaller herds. Larger dairies also submitted specimens more frequently. Dairies in the northern part of the state were more likely to submit specimens and submitted more frequently than southern herds when herd size was accounted for in the analysis. Mean submission rate (+/- SD) for the 970 submitting dairies was 1.4 (+/- 1.8) submissions/year. Forty-six percent of the dairies accounted for 80% of submissions, whereas only 14% of dairies accounted for 50% of all diagnostic dairy submissions.

Animals↗

PubMed1991

Molecular epidemiology of Pasteurella multocida in turkeys.

Pasteurella multocida isolated from turkeys during an outbreak of fowl cholera was characterized by serotype and heterogeneity of genes encoding rRNA (ribotype) to investigate the epidemiology of the organism. Isolates were collected between October 1985 and July 1986. The M9 or Clemson University fowl cholera vaccine-like strain was detected in 17% of the flocks with fowl cholera. One particular strain, isolated only from breeder flocks, was recovered from 7 of the 10 breeder flocks examined in this study. Intracompany transmission appeared to be common, implying a failure in biosecurity. Circumstantial evidence indicated that in the field; the incubation period of P multocida in a turkey flock may be between 2 to 7 weeks. Wildlife did not appear to be an important reservoir of P multocida for turkeys during this study period. Ribotyping results tended to discount several of the possible interflock transmissions, as suggested by examination of serotyping results alone; however, serotyping in combination with ribotyping proved helpful in understanding the epidemiology of P multocida in turkeys.

Animals↗

PubMed1991

Evaluation of multiple reticulorumen selenium pellets as a health risk in growing Hereford steers.

Five groups of Hereford steers were monitored for 293 days. One group of 3 was not given selenium supplementation; the other 4 groups of 3 steers each were given 2, 4, 6, or 8 reticulorumen selenium pellets. Health, body weight, and blood selenium concentration were monitored during the study. At the finish, steers were slaughtered, and various tissues from the carcasses were analyzed for selenium content. Initial blood selenium concentration did not differ significantly among groups. However, significant (alpha = 0.01) difference among means was detected during the early period of rapid increase in blood selenium concentration in steers of supplemented groups. Means of maximal blood selenium concentration also differed among groups; however, even the highest value, 0.253 micrograms/g, was lower than the 3 micrograms/ml reported in chronic clinical cases of toxicosis in the literature. Carcass analysis indicated significant (alpha = 0.05) differences in selenium concentrations among treatment groups for almost all tissues tested. Only kidney samples (7.9 micrograms/g) from steers of the 8-pellet treatment group exceeded published normal values (7.6 micrograms/g). Health variables for most dates were not significantly different among groups, and selenium toxicosis was not evident in any steer. Analysis did not indicate risk to human beings consuming tissues from these steers.

Analysis of Variance↗

PubMed1991

Case control study of fowl cholera in meat turkeys in California from August 1985 through July 1986 [corrected].

From Aug 1985 through July 1986, 720 meat turkey flocks on 160 California premises were monitored and outbreaks of fowl cholera (Pasteurella multocida) were investigated. Data from 43 outbreak (case) flocks were compared with data from 43 nonoutbreak (control) flocks. Outbreak flocks, compared with control flocks, were more likely to be located on premises with higher maximal bird capacity and history of fowl cholera outbreaks. The overall impression was that flocks in larger, newer, more intensively managed premises were at greater risk of fowl cholera outbreaks than were other flocks.

Animals↗