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D W MacVean

Publications and source records attributed to D W MacVean.

12 recordsLinked to original sources
PubMed1989

Risk factors for lower respiratory tract disease in a cohort of feedlot 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.

Animal Husbandry↗
PubMed1988

Use of a disease reporting system in a large beef feedlot.

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.

Animals↗
PubMed1988

Validation of disease diagnoses reported to the National Animal Health Monitoring System from a large Colorado beef feedlot.

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)

Animals↗
PubMed1988

Prevalence and specificity of antibodies to bovine respiratory syncytial virus in sera from feedlot and range cattle.

The specificity of serum antibodies for the polypeptides of bovine respiratory syncytial virus (BRSV) was examined, using sera obtained from feedlot and range cattle. Test results in sera from feedlot cattle indicated a 60% rate of seroconversion and 95% seropositivity to BRSV, associated with lack of clinical signs indicative of respiratory tract disease. Exposure to other common respiratory tract viruses also was high (greater than or equal to 92% to bovine herpesvirus type 1, bovine viral diarrhea virus, and para-influenza virus type 3). Test results in sera from range cattle indicated BRSV seropositive rates of 28% in calves, 49% in yearling cattle, and 70% in mature cows; clinical signs of respiratory tract disease were not observed in these cattle. Antibodies to BRSV in sera from cattle in both environments reacted predominantly with polypeptides of molecular weight 80,000 through 85,000, 40,000, and 28,000. Reactivity to a glycoprotein of molecular weight between 43,000 and 44,000 and to several glycopolypeptides of smaller molecular weight increased in serum specimens obtained from feedlot cattle between time of entry into the feedlot and slaughter.

Animals↗
PubMed1986

Airborne particle concentration and meteorologic conditions associated with pneumonia incidence in feedlot cattle.

To elucidate the role of air quality on the occurrence of pneumonia in feedlot cattle, the following environmental values were measured at a feedlot: suspended particulates in 5 particle-size fractions, relative humidity, air temperature, and barometric pressure. Pneumonia incidence data were classified by the number of days the cattle had been at the feedlot (days on feed). The concentration of airborne particles, range of temperature, days on feed, and season of the year were associated with incidence of pneumonia in cattle. Pneumonia incidence rates were greatest both within 15 days of arrival at the feedlot and during the fall sampling periods. The incidence of pneumonia in the 16 to 30 days-on-feed group was closely associated with the concentration of particles 2.0 to 3.3 microns in diameter and the range of daily temperature when exposure occurred 15 days before the onset of disease in the fall and 10 days before in the spring.

Air Pollutants↗
PubMed1978

Use of cytology for tumor diagnosis in private veterinary practice.

Cytologic and histologic services were offered without charge to veterinarians in the greater Tulsa area by the Tulsa Registry of Canine and Feline Neoplasms. During the first 3 years of operation, all veterinarians treating dogs or cats used the histologic service and slightly less than one-half used the cytologic service. The number of cytologic accessions increased 77% during the 2nd year and 27% during the 3rd year. For corresponding years, the increase in histologic accessions was 5% and 11%. The 7 hospitals from which 79% to 90% of the cytologic specimens were received were compared with the 8 to 14 hospitals that used cytologic service infrequently. The frequency of use of cytology was not related to number of veterinarians in the hospital, number of animals seen in the hospital, or number of tissues received by the Registry from the hospital. The order of frequency of the most numerous cytologic specimens was fine-needle aspirations of masses in or beneath the skin, mammary preparations, effusion sediments, fine-needle aspirations from lymph nodes, and urine sediments.

Animals↗
PubMed1978

Frequency of canine and feline tumors in a defined population.

The Tulsa Registry of Canine and Feline Neoplasms was the second animal tumor registry in the United States concerned with a defined population in a delimited geographic area. Only tumors histologically confirmed by registry pathologists were included in frequency statistics based on the annual dog and cat population presented to veterinarians. During the first registry year, about 1% of the 63,504 dogs and 0.5% of the 11,909 cats had one or more primary tumors. While the incidence rate for malignant tumors in dogs was similar to that in cats, the incidence of benign tumors of dogs was over 10 times that of cats. The most common tumors were sebaceous adenoma in dogs and lymphosarcoma in cats. Mammary cancer was the most common malignant tumor in dogs. Mammary tumors of female dogs were significantly more frequent in Pointers, Poodles and Boston Terriers, in that order, than in other breeds. A greater incidence of mammary tumors among intact compared to spayed female dogs was seen for virtually every age group except in the Pointer breed.

Age Factors↗
PubMed1978

Alphaviruses in Peninusular Malaysia: I. Virus isolations and animal serology.

A survey of the activity of three alphaviruses (Sindbis, getah and chikungunya) in Peninsular Malaysia was conducted between 1962 and 1970. Serum samples were examined from 3,917 vertebrates representing a wide variety of wild and domestic animals throughout the peninsula for hemagglutination-inhibiting and neutralizing antibodies. A total of 548,939 mosquitoes were collected from different habitats, including jungle, rural, suburban and urban areas, and the majority of the females taken were examined for the presence of virus. Two strains of Sindbis virus and one strain of getah virus were isolated from pools of Culex mosquitoes collected in and around domestic animal shelters. Analysis of the serological results indicated that, 1) getah virus is associated principally with large domestic animals, particularly swine, 2) Sindbis virus is associated with large domestic animals and birds, especially domestic ducks, and 3) chikungunya virus, which has not yet been isolated in Malaysia, appeared to be present at a very low level of activity, probably with wild monkeys as the vertebrate hosts.

Animal Population Groups↗