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The world literature was searched to document the variables known to affect the initiation, spread, maintenance, and/or control of bovine brucellosis. Each variable was classified into 1 of 3 categories, depending upon whether it was related to the animal population, to management, or to the biology of the disease. These variables were documented and categorized as the initial step for a quantitative path analysis on the epidemiology of bovine brucellosis in a defined geographic area in northern Mexico.

Two doses of a formalin-killed, cell culture-derived vesicular stomatitis virus (vsv)-New Jersey serotype vaccine were administered intramuscularly, 30 days apart, to all lactating and nonlactating cows in a 350-cow dairy herd. Serum specimens were obtained serially from 96 cows before vaccination and at 30, 52 and 80 days after vaccination and from 24 of these cows 175 days after vaccination. Serum neutralizing antibody titers to vsv-New Jersey serotype were determined from serum-dilution, plaque-reduction tests. Serum neutralizing antibody titers also were determined during the same period for 67 nonvaccinated heifers in the herd. Peak group geometric mean serum neutralizing antibody titers of 1:530.46 +/- 1.14 (group geometric mean titer log10, 2.725 +/- 0.055) developed 21 days after the second vaccination, but decreased to a low value of 1:65.36 +/- 1.38 (group geometric mean titer log10, 1.815 +/- 0.142) by 175 days after vaccination. The nonvaccinated group had no detectable antibody titer to vsv-New Jersey serotype throughout the study. All serum specimens from the vaccinates and controls were negative for heterologous reactivity to vsv-Indiana serotype.

Data for path analysis on the epidemiology of bovine brucellosis were gathered from 184 premises in Mexicali Valley, Mexico, that had dairy cattle, swine, and/or goats. Each farmer manager or owner was interviewed, using a pretested set of questions, and the livestock on the premises were serotested for Brucella antibodies. The focus in gathering these data was to identify the characteristics of premises with seropositive cattle in comparison with characteristics of premises with no seropositive cattle.

Using data collected from company lot records, potential risk factors related to feedlot management, the cattle, and climate were determined. The risk factors were analyzed by use of weighted multiple regression techniques to determine their effects on the incidence of lower respiratory tract disease in a cohort of 95 lots containing 17,696 cattle. The gender of the cattle, the number of days that groups of cattle filled a lot, pregnancy checking of heifers, and the average temperature change in the first 14 days in which the cattle were on feed significantly influenced the incidence of lower respiratory disease. The incidence of lower respiratory tract disease was most influenced by risk factors in the first 30 days on feed.

Clinical observation and collection of biological specimens from a large beef feedlot (approximately 30,0000 animals) were used to evaluate 6 approaches for validation of a disease reporting system. Data collected during a 12-month period were used to evaluate each approach. A subsample of disease cases reported to the National Animal Health Monitoring System (NAHMS) was compared with the clinical observations of the investigators. Although the agreement between clinical diagnosis by the NAHMS veterinarian and by feedlot health crews was high, the sensitivity and specificity of specific diagnoses varied from 100 to 18% and from 99 to 76%, respectively, which suggests that regular clinical observations by a veterinarian are needed to validate disease diagnoses reported to NAHMS by producers. Subsampling of a group of cattle by means of paired serologic determination of antibodies to infectious bovine rhinotracheitis virus, bovine viral diarrhea virus, bovine respiratory syncytial virus, and parainfluenza-3 virus revealed a high serologic conversion rate to infectious bovine rhinotracheitis, and high levels of preexisting antibody to bovine respiratory syncytial and parainfluenza-3 viruses. It was concluded that the current method of data collection for Colorado feedlots provides an acceptable level of sensitivity and specificity for the program. However, disease events that are not of economic importance to the feedlot operator will be underestimated. If an objective of NAHMS is to develop a base line of animal health conditions, diagnosis of diseases by current methods will be satisfactory. Occasional validation through clinical observations by a veterinarian will suffice to monitor quality of collected data.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiologic and etiologic data about diarrhea in foals were collected under a planned prospective recording and monitoring study. The survey and monitoring procedures included a survey to obtain an overview of current horse management practices on participating farms, a daily health record survey to obtain information on mares and their foals, and collection of feces from 19 of 144 diarrheic foals and 10 age-matched nondiarrheic foals for electron microscopy, ELISA for rotavirus, and bacteriologic culture. Coronavirus was detected in the feces of diarrheic as well as clinically normal foals. Rotavirus was detected in the feces of diarrheic foals only. With regard to agents found in the feces, there was no significant (P less than 0.05) difference between diarrheic and nondiarrheic foals. Half of the 297 foals on which data were available developed diarrhea. Most foals that developed diarrhea lacked other clinical manifestations of disease. Basic cleanliness at foaling was associated with a lower percentage of foals developing diarrhea. Prophylactic use of antibiotics and vitamins in newborn foals was associated with a higher percentage of foals developing diarrhea. A higher percentage of foals born to visiting mares developed diarrhea, compared with foals born to resident mares.

Multiple logistic regression was used to investigate prognosis in 308 horses referred to the University of Minnesota veterinary teaching hospital with colic. Bivariate results identified the following significant individual parameters: absent or hypomotile abdominal sounds, medical or surgical classification, peritoneal fluid total protein, anion gap, serum glucose, capillary refill time, blood pH, heart rate, packed cell volume, base excess, serum chloride, plasma bicarbonate, serum urinary nitrogen and age. Two multivariable prognostic models were developed using logistic regression. Model I (based on 257 cases with a mortality rate of 39%) included age, sex, medical or surgical classification, capillary refill time, packed cell volume and heart rate. Model II (based on 138 cases with a mortality rate of 48%) included age, sex, medical or surgical classification, capillary refill time, serum bicarbonate, serum chloride and respiratory rate. Predictive performance of the models was evaluated by treating the calculated probability of death for each horse as a continuous test result. The influence of varying the probability cutoff point for death on test characteristics (sensitivity, specificity and positive and negative predictive values) was determined. These models have not been validated and thus their performance in a different population is uncertain.

Data related to rates of disease and their associated costs were collected for 12 months from 2 sheep feedlots in northern Colorado. There was an apparent seasonal occurrence of many of the diseases. Pneumonia, enterotoxemia, acidosis, and transport tetany accounted for most of the diseases seen in these feedlots and were responsible for most of the economic losses. There was a large difference in the incidence of diseases between the 2 feedlots and in the expenditures for disease prevention between the 2 feedlots.

A total of 116 cows from 4 dairy herds in California were used to determine the sensitivity and specificity of extracellular antigen of Nocardia astero des for possible detection of bovine mastitis caused by N asteroides and N caviae. Three different positive criteria were used. These criteria gave different sensitivity and specificity to the skin test. The highest sensitivity of 80% and highest specificity of 96.04% were obtained by combining 2 criteria. The study found no cross-reaction between N asteroides antigen and Mycobacterium fortuitum or N asteroides and tuberculin skin tests. There was cross-reaction between N asteroides antigen and N caviae infection.

Twenty-eight known or hypothesized variables in the epidemiology of bovine brucellosis were examined by path analysis to determine the contribution of each variable to seropositivity of cattle in Mexicali, Mexico. The variables that contributed significantly to bovine seropositivity were area size of farm premises, percentage of animals on a premises that were inseminated artificially, local marketing of the products from a premises, size of investment in the livestock, whether or not dairying was the major agricultural activity of the premises, and the policy of the owner or manager with regard to disposal of reactor animals. The contributions of all other variables were insignificant.

A large commercial beef feedlot in northeastern Colorado was selected by stratified random process for inclusion in the National Animal Health Monitoring System pilot data collection project. Various records in the feedlot were used to collect data related to animal health conditions and to their costs. A total of 57,727 cattle were processed during the 12-month period of the study. Rates were used to adjust for the number of cattle in the feedlot during that period. The disease incidence, culling rate, and death rate were presented by each month in the study. The monthly mean number of cattle was the denominator for these rates. During the 12 months, 72 diseases or abnormal conditions were recorded. The total cost of the 10 most prevalent diseases (itemized by dead, culled, treatment, and income from selling dead animals) accounted for approximately 77% of the total cost of disease in the feedlot. The total cost of lower respiratory tract diseases contributed approximately 46% of the total disease cost, and 60% of the cost of the 10 most prevalent diseases. In order to consider the reporting methods reliable, a separate study was undertaken to validate a reported disease or condition in the feedlot.