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Biomedical subjects

S A Dee

Publications and source records attributed to S A Dee.

28 records · Page 2Linked to original sources
PubMed1997

Indirect fluorescent IgM antibody response of pigs infected with porcine reproductive and respiratory syndrome syndrome virus.

IgG and IgM antibody responses were examined by an indirect fluorescent antibody method in pigs following inoculation with different porcine reproductive and respiratory syndrome virus (PRRSV) isolates or a vaccine virus. Viremia was also examined in the pigs. The IgG antibody was first detected between 9 and 14 days post inoculation (PI) and maintained high titers for at least 7 weeks PI. No change in IgG antibody titers was observed when the pigs were reinoculated with PRRSV 35 days PI. IgM antibody was detected between 5 and 28 days PI in the pigs. Reinoculation at 35 days PI caused a short term rise of IgM antibody. Virus was isolated from sera collected between 2 and 21 days PI. The IgM antibody was detected regularly in sera collected during viremia and up to 1-2 weeks after the viremic periods. These results suggest that pigs with detectable IgM antibody are probably pigs with recent infection and that routine testing of IgM antibody in purchased breeding pigs from seropositive farms may be useful in identification of pigs with recent infection.

Animals↗
PubMed1996

Improved performance of a large pig complex after sequential nursery depopulation.

An attempt was made to compare the productivity and financial benefits of nursery depopulation on five large pig farms which were all part of one complex. Each farm had been experiencing poor post weaning performance for 12 months, and had previously been infected with porcine reproductive and respiratory syndrome virus (PRRSV). A plan to depopulate each nursery sequentially was established, and the pigs were moved to fattening facilities on one of the farms (farm 3) where space was available. Over a four week period, the nurseries of farms 1, 2, 4 and 5 were emptied, cleaned and disinfected, and any changes in nursery performance, mortality and the seroprevalence of antibodies to PRRSV were then assessed for one year. The financial benefit to the entire farm complex was analysed by using partial budget methods. During the year a net benefit of $1,708,431 was assessed to the farm complex owing to the increased numbers of marketable pigs and the reduced antibiotic costs. There were highly significant improvements in nursery growth rate and decreases in mortality on farms 1, 2, 4 and 5, and antibodies to PRRSV were detected on farms 3 and 4 but not on farms 1, 2 and 5. The inability to empty the farm 3 fattening facility, which housed the pigs from the other sites, may have led to the maintenance of its PRRSV positive status and could have served as the source of virus for farm 4.

Animal Husbandry↗
PubMed1994

Recurrent reproductive failure associated with porcine reproductive and respiratory syndrome in a swine herd.

An investigation of a case of recurrent reproductive failure in a swine herd was conducted. The subject farm (A) and a neighboring farm (B) had experienced an acute outbreak of porcine reproductive and respiratory syndrome in 1990. During 1992, farm A experienced recurrent episodes of conception failure, stillbirths, preweaning mortality, and sow mortality. Similar clinical findings were not evident on farm B. Evaluation of production records indicated that the problem was occurring in first-parity litters. It was learned that replacement gilts for farm A were being purchased from an outside source, whereas farm B raised its own replacement gilts. Indirect fluorescent antibody testing of gilts from both farms indicated a high prevalence of seronegative gilts on farm A vs a high prevalence of seropositive gilts on farm B. Although there is no correlation between indirect fluorescent antibody titers and immunity, it would appear that exposure to porcine reproductive and respiratory syndrome virus prior to breeding is essential to prevent reproductive disease.

Animals↗
PubMed1994

Prevention of the spread of porcine reproductive and respiratory syndrome virus in endemically infected pig herds by nursery depopulation.

An attempt was made to prevent the spread of the virus of porcine reproductive and respiratory syndrome (PRRS) on three Minnesota pig farms that had been experiencing chronic nursing pig problems, including poor growth rates and increased mortality of post weaning pigs. The PRRS virus and different bacterial pathogens were isolated from all three farms during the initial investigation, and all the farms had a high prevalence of PRRS virus-seronegative breeding animals. All the pigs tested within one week after weaning when they were 18 to 22 days old, were seronegative, whereas 80 to 100 per cent of the pigs tested at eight to nine weeks had antibody titres ranging from 1:64 to 1:1024 by an indirect fluorescent antibody method. The seroprevalence among the finishing pigs on the three farms ranged from 25 to 50 per cent. An eradication protocol was established on each farm, involving emptying the nurseries, followed by pumping out the slurry pits and cleaning, washing and disinfecting three times in 14 days. After the nurseries were repopulated there were improvements in nursery mortality and average daily weight gain, and no seropositive animals were detected in the nurseries on any of the farms; the seronegative status was maintained for the six-month testing period.

Animal Husbandry↗
PubMed1993

Effect of management practices on the Streptococcus suis carrier rate in nursery swine.

Management practices on swine farms were analyzed to determine factor(s) associated with high prevalence of pigs that were carriers of Streptococcus suis. Samples were obtained for bacteriologic culture via direct swabbing of palatine tonsils of healthy nursery pigs on 35 farms throughout the United States. Overall, 36.7% of the pigs were determined to be carriers. Isolates of S suis were serotyped, and antimicrobial susceptibility tests were performed by use of Kirby-Bauer techniques. Streptococcus suis types 1 and 2 were most commonly isolated. All isolates were susceptible to enrofloxacin, 97% of the isolates were susceptible to ceftiofur, and 94% were susceptible to ampicillin. However, only 80% of the isolates were susceptible to penicillin, and only 18% were susceptible to tetracycline. Environmental, managerial, nutritional, and health factors were measured on each farm. Excessive temperature fluctuation, high relative humidity, crowding, and an age spread of > 2 weeks between pigs in the same room were the 4 most commonly encountered problems on farms with higher-than-average percentages of carrier pigs. Continuous flow facilities were found on 50% of these farms, and various disease problems, vitamin E/selenium deficiency, inadequate vaccination programs (attributable to the presence of atypical serotypes), and penicillin-resistant strains were found on 6 to 28% of these farms. Overall, 83% (15/18) of farms with higher-than-average percentages of carrier pigs also had a history of clinical S suis disease.

Animal Husbandry↗
PubMed1992

Porcine urogenital disease.

Porcine urogenital disease is the result of an imbalance of the normal microflora of the urinary and reproductive tracts brought about by hormonal, environmental, and management-related stress factors. Production and economic losses can be substantial, and diagnosing and treating the problem can be frustrating. Through proper hygiene, facility design, and culling procedures, the severity of the problem can be minimized.

Animals↗
PubMed1992

Isolation of a cytopathic virus from weak pigs on farms with a history of swine infertility and respiratory syndrome.

Severe clinical signs of swine infertility and respiratory syndrome (SIRS) of unknown cause were observed in several Minnesota swine farms between November 1990 and March 1991. Forty-five lung samples of weak pigs were collected from 13 swine farms, and virus isolation was attempted using swine alveolar macrophage (SAM) cultures. A cytopathic virus was isolated from 19 lung samples collected from 6 different farms. Four pregnant sows were infected intranasally with a tissue suspension from which virus was isolated, and 4 6-week-old pigs and 2 contact pigs were infected intranasally with 1 of the isolates. The 4 sows farrowed 12 stillborn and 32 normal pigs. Virus was recovered from 10 of 19 pigs examined. Infected 6-week-old pigs were clinically normal except for slightly elevated rectal temperatures and mild respiratory signs. No or mild interstitial pneumonic lesions were observed in inoculated pigs, but the lesion was obvious in the 2 contact pigs. Seroconversion was observed in sows and pigs as measured by indirect fluorescent antibody (IFA). Serologic identification of the isolates was carried out by IFA using reference serum prepared from an experimentally infected sow. A cytoplasmic fluorescence was observed on the SAM monolayers infected with each of the 19 different isolates. Fluorescence was also observed when the monolayers were tested with SIRS virus ATCC VR-2332-infected sow sera. Replication of the isolates was not affected in the medium containing 5-iodo-2'-deoxyuridine but was inhibited by treatment with ether. The isolates were relatively stable at 56 C and did not agglutinate with various erythrocytes tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

In utero infection of swine fetuses with infectious bovine rhinotracheitis virus (bovine herpesvirus-1).

The pathogenesis of infectious bovine rhinotracheitis (IBR) virus (bovine herpesvirus-1) was studied in porcine fetuses after in utero inoculation. Laparotomies were performed on 8 seronegative pregnant sows at 34 to 86 days of gestation, and all fetuses in 1 uterine horn of each sow were exposed to IBR virus via inoculation into the amniotic sacs. Fetuses in the other horn served as controls. Clinical signs of infection were not observed in the sows, except for 2 sows that aborted at postinoculation days (PID) 11 and 15. Fetuses of the remaining 6 sows were collected at slaughter on PID 15 to 28. Fetuses were examined for gross abnormalities, presence of IBR virus in tissues, and the formation of neutralizing antibodies to IBR virus. Of 33 inoculated fetuses from 6 sows, 10 were mummified, 11 were hemorrhagic and/or edematous, and 12 were alive. Necrotic lesions were observed on the skin and in the liver of dead and live fetuses. Virus was recovered from 29 of 33 inoculated fetuses. Infectious bovine rhinotracheitis virus was isolated from fetal skin, liver, lungs, kidney, spleen, stomach contents, brain, amniotic fluid, and placenta. Virus was isolated from 4 of 11 fetuses recovered from 1 aborting sow. Antibodies to IBR virus were not detected in sera from the sows. However, antibodies were detected in 6 of 15 fetuses inoculated at 63 to 86 days of gestation and collected at slaughter at 86 to 112 days of gestation. The youngest fetus with detectable IBR antibody was estimated to be 74 days of gestation by measuring crown-rump length of the fetus.

Abortion, Veterinary↗