Aujeszky's disease: sanitation of swine herds in enzootically infected areas using labelled vaccines

Both in the Federal Republic of Germany and in some neighbouring countries the epizootic situation of Aujeszky's disease has been unsatisfactory for a long time, especially in areas with a high pig density. New findings on vaccines with certain protein deletions have recently indicated the possibility that the disease might be eradicated even in vaccinated herds. By using labelled vaccines it seems possible to distinguish the carriers of vaccine virus antibodies from the carriers of field virus antibodies and to eliminate the animals infected with field virus, while leaving the other animals in the herd and protecting them from infection by vaccination. This procedure would also be practicable in epizootically infected areas and would be less expensive than eradicating the disease on the basis of serological tests without using vaccines. A skeleton of an eradication programme, which was discussed and agreed with scientific experts and with the Federal Laender, as well as rough estimates of costs are being presented.     

Water medication of a swine herd with amoxycillin

A swine herd, consisting of 201 swine, was treated with amoxycillin. Amoxycillin was administered in the water system for 5 days, at a mean dose of 23 mg/kg body weight per day. Twice a day the water consumption was monitored, and blood samples collected from 10 randomly selected pigs. The plasma concentration of amoxycillin was measured by use of high performance liquid chromatography (HPLC). Three days after initiating amoxycillin treatment, the plasma concentration reached a constant level, at which it varied between a maximum of 1.3 μg/mL and a minimum of 0.5 μg/mL. The plasma concentration was compared with a predicted curve based on pharmacokinetic variables obtained previously. The plasma concentrations were at the same level as the simulated ones. The minimum inhibitory concentration (MIC) values of the common respiratory pathogens Actinobacillus pleuropneumoniae and Pasteurella multocida are about 0.1 μg/mL. In pigs the distribution between bronchial mucosa and plasma ( AUC _mucosa/ AUC _plasma) is 0.3, which indicates a therapeutic plasma concentration of 0.3 μg/mL. Data from the present study indicates that water medication with amoxycillin is effective as follow-up treatment.     

Reproductive consequences of an X-autosome translocation in a swine herd.

A survey was conducted on the chromosome makeup and breeding data of pigs housed at the Arkell Research Station, University of Guelph, to determine the reproductive impact of a reciprocal translocation previously identified as t(Xp+;14q-). Blood samples were cultured and chromosome spreads were examined to identify carriers in the herd. Gonadal features of carrier boars and piglets and their age-matched normal counterparts were studied, and the reproductive history of carrier sows, including the number of breedings required for conception, mean litter size, prevalence of still births and malformations, and sex distribution among the piglets, was compared with that of normal (noncarrier) sows. Our observations on testicular histology confirmed that X-autosome translocation-carrier boars are sterile, and the analysis of reproductive data showed that the most striking effects of t(Xp+;14q-) on sows are the 50% increase in the number of breedings required for conception and the over 25% reduction in litter size compared with that of normal sows. The reproductive impact of this and similar translocations on the herd and on the swine industry in general is discussed.     

Efficacy of oral vaccination against swine erysipelas in growing-finishing pigs in a clinically infected Slovakian pig herd

In a large Slovakian growing-finishing pig production unit, the effects of oral vaccination against swine erysipelas (SE) were investigated in three groups of pigs of 10 weeks of age. In group 1, the pigs were vaccinated intramuscularly at 1 and 3 weeks after arrival in the growing-finishing barn using an Erysipelothrix rhusiopathiae bacterin. Group 2 pigs were vaccinated at the same time as group 1 using an oral avirulent live SE vaccine administered through drinking water; the pigs in the third group were placebo treated. Clinical signs of acute SE, arthritic changes, average daily weight gain (ADG), feed conversion ratio, and mortality were evaluated. None of the pigs in groups 1 and 2 but 31.7% of the control animals (group 3) showed typical clinical signs of acute SE. More (P<0.01) non-vaccinated pigs had chronic arthritic changes compared with groups 1 and 2. No significant differences in mortality were recorded between the groups. Groups 1 and 2 had higher (P<0.05) ADG and lower feed conversion ratios compared with group 3 pigs. The results demonstrated that the oral avirulent live culture was efficacious in significantly reducing the clinical symptoms caused by E. rhusiopathiae infection, so enhancing the pigs' performance.     

Lightning injury in an outdoor swine herd.

Three pigs, weighing 63 kg-70 kg each, from a group of 8 pigs in an outdoor pen that was struck by lightning were necropsied. All 3 pigs presented with hind limb paralysis. The only lesions identified were multiple fractures of the last (seventh) lumbar vertebral body and first sacral vertebral segment, with dorsal displacement of the sacrum and transection of the distal spinal cord and spinal nerves. Hemorrhages extended from the fracture sites into muscles immediately surrounding the lumbosacral junction and retroperitoneally into the pelvic cavity. These hemorrhages were not clearly visible until the pelvic region was dissected. Lesions commonly found in human lightning-strike victims were not present in these pigs. Because vertebral fractures may be the only lesions and may be grossly subtle in heavily muscled pigs, careful pelvic and vertebral dissection is recommended in cases of suspected lightning strike and electrocution.     

Impacts on conceptus survival in a commercial swine herd

An estimated 30 to 40% of potential piglets are lost before farrowing in U.S. or European pig breeds. Because these studies were conducted in limited numbers of university research herds, we decided to characterize the timing, pattern, and extent of conceptus loss in a commercial swine herd in Iowa (Pig Improvement Company; Camborough Line). Sows (parities 2 to 14) were slaughtered on d 25 (n = 83), 36 (n = 78), or 44 (n = 83) of gestation. These days coincide with periods before, during, and after uterine capacity becomes limiting to conceptus survival. At slaughter, numbers of corpora lutea (CL) and uterine horn length were determined, and conceptuses were removed and evaluated. Uterine horn length and CL number did not differ among these days of gestation, averaging 217 cm and 26.6 CL, respectively. In contrast, numbers of conceptuses decreased (P < 0.05) from 15.8 on d 25 to 12.9 on d 36, then remained relatively constant through d 44 (12.1). Thus, conceptus survival averaged 60.2% on d 25, 50.1% on d 36, and 46.3% on d 44, based on numbers of CL present. There was a positive correlation (P < 0.001; r = 0.50) between numbers of viable conceptuses on d 25 and ovulation rate, but this association was completely lost by d 36 (P > 0.10) when uterine capacity becomes limiting. In agreement with this premise, uterine horn length and conceptus number were not associated on d 25 but exhibited positive correlations (P < 0.05) on d 36 (r = 0.36) and d 44 (r = 0.40). On all 3 d examined, the numbers of viable conceptuses were not associated with fetal weight but were negatively correlated (P < 0.05) with placental weight. Compared with the commonly reported values for ovulation rate and percentage conceptus loss in university research herds, values from these production animals were extremely high. Data suggest that throughout this period, larger litters were associated with conceptuses exhibiting small placentae. These data lend support to the concept that increased placental efficiency (fetal weight/placental weight) may contribute to increased litter size in the pig.     

Chlamydial infection and perinatal mortality in a swine herd

Chlamydia psittaci was believed responsible for an episode of high perinatal death loss in a swine herd in which 8.5 pigs per litter normally were weaned. In this episode, 18 sows produced 186 pigs, with 50 survivors. Chlamydia was found in tissue samples, and other bacterial or viral pathogens could not be identified. Chlamydia was diagnosed by isolation (ELISA), histologic examination using immunoperoxidase staining techniques, and electron microscopy. Previously, C psittaci has not been considered in the differential diagnosis of swine perinatal mortality.     

我国猪群健康管理体系的构建

新中国成立以来,养猪业在我国得到了较快发展,我国城镇居民人均猪肉消费量由1957年的6.72千克升至2007年的18.21千克,我国的猪肉产量由1983年的1 316.1万吨升至2007年的4 287.8万吨。特别值得一提的是,我国农村居民肉类消费的增长更快,猪肉消费占居民消费的比重较高,我国猪的饲养量占世界总饲养量的一半,由此可见,养猪业在我国农业中的地位举足轻重。     

Porcine group C rotavirus as a cause of neonatal diarrhea in a Quebec swine herd.

A porcine group C rotavirus was found to be the unique cause of a problem of enzootic neonatal diarrhea in a minimal disease herd composed of 190 sows on a continuous farrowing program. During the outbreaks of diarrhea, 10 to 80% of the litters were affected with a morbidity rate of 100% and case fatality rates of 5 to 10%. Clinical signs began 24 to 48 h after birth and were characterized by a profuse yellow diarrhea lasting a few days. Piglets from different outbreaks of diarrhea were necropsied. They had multifocal villous atrophy in the small intestine, especially in the ileum. Group C rotavirus was demonstrated by direct immunofluorescent staining of frozen intestinal sections and by polyacrylamide gel electrophoresis of viral RNA extracted from the intestinal contents of diarrheic piglets. The infection with clinical illness and lesions was reproduced experimentally in newborn piglets by oral inoculation of a suspension prepared from a pool of intestinal contents from diarrheic piglets.     

Financial evaluation and decision making in the swine breeding herd.

As the swine industry continues to evolve and develop a greater business orientation--one that demands justification of costs, benefits, and risk-exposure--the veterinarian will be confronted with the need to develop an economic basis to supplement the biologic. The profession should view such a challenge as an opportunity to broaden its role in serving the businesses that make up the industry. However, to be effective in such an expanded role requires that the veterinarian develop a good working knowledge of risk and risk management as well as the role played by economic evaluation techniques used in financial evaluation in the risk management process. Several potential advantages exist for the veterinarian who determines to expand his or her risk management role by using financial evaluation in the course of day-to-day practice routine: Additional service or consulting income may be generated through evaluating alternatives through decision analysis. Client confidence may be strengthened in the veterinarian and in the recommendations made. The costs of consulting services and health products for the client may be viewed as income-generators instead of being viewed solely as expenses. Referrals of additional progressive clients may be generated by satisfied current clients. The veterinarian may achieve personal satisfaction through substantiating his or her recommendation beyond clinical or experimental judgment. With the capability of using financial evaluation techniques in the evaluation and justification of recommendations comes significant responsibility. Reliance upon financial evaluation techniques as a more objective approach in the management of risk for clients carries with it an inherently greater degree of trust. Such trust must be deserved. The universal adage "garbage in, garbage out" applies directly to financial evaluation. Financial evaluation techniques have the potential to provide the decision-maker with objective and accurate analysis, improving the probability of choosing an optimal course of action for the business. However, the objectivity and accuracy achievable is highly dependent upon the quality and quantity of information used in the analysis. Veterinarians must be cognizant of the increased responsibility demand placed on those using financial evaluation techniques to direct the course of action for their clients. Financial evaluation tools are available to decision-makers that may improve the objectivity of the decision-making process, providing for a greater degree of confidence in the expected outcome. Stated another way, these tools can reduce the number of surprises a decision-maker encounters as a result of the decisions made.(ABSTRACT TRUNCATED AT 400 WORDS)     

Economic assessment of a pseudorabies epizootic, breeding herd removal/repopulation, and downtime in a commercial swine herd

The effect of pseudorabies in a 150-sow farrow-to-finish operation on selected production and economic values was estimated. Mean litter size remained the same throughout the observation period; however, there was a 2-fold increase in suckling pig mortality and a 3.5-fold increase in stillbirths when the months of the epizootic were compared with pre-epizootic months. Following the epizootic, suckling pig mortality was 13.7% greater (P less than 0.05) than that observed in the months preceding the epizootic, whereas stillbirth rate was 71% higher (P less than 0.01) than that reported in the pre-epizootic months. Total net loss for this operation was estimated at +48,175. The major economic losses (approximately 88% of the total loss) were related to breeding herd removal/repopulation and production downtime.     

A longitudinal study of rotavirus antibody titers in swine in a closed specific pathogen-free herd.

In a newly established closed specific pathogen-free (SPF) swine herd, gilt/sow suckling and weaned pig rotavirus specific antibody titers were followed for three lactations by enzyme-linked immunosorbent assay (ELISA) to gain insight into the dynamics of herd antibody titers to group A rotavirus. Among gilts/sows, serum antirotavirus IgG titers increased during each lactation with a subsequent drop in titer between farrowings. Serum antirotavirus IgM titers declined during each lactation and with subsequent parity. Serum antirotavirus IgA titers remained constant during lactations and among parities. In colostrum and milk, antirotavirus IgA antibody was abundant. Differences in titer were not noticed between gilts and second litter sows but third litter sows had significantly higher titers than the first two groups. Antirotavirus IgG was high in colostrum but nearly nonexistent in milk. This titer did not vary significantly within or among parities. There was a linear regression in the titers of baby pig serum antirotavirus IgG from the post colostral sample through to seven weeks old, after which titer began to increase. No difference in baby pig serum antirotavirus IgG was noted among the three litters. Serum antirotavirus IgA and IgM were undetectable in baby pig sera after 2-3 weeks of age. Coproantibody to rotavirus was sporadically present in pig feces for 2-3 weeks after birth with highest titers in the IgA fraction. We conclude that although it is probable that age resistance of pigs to rotavirus diarrhea occurs, humoral immunity as measured by ELISA rotavirus antibody titers may not be intimately involved in virus clearance since in our studies baby pigs passively received large amounts of antibody but still excreted pathogenic virus. The finding of increasing levels of serum antirotavirus IgG in gilt/sow serum suggest that exposure to antigen of dams occur without significant increases in antirotavirus IgG titers in either colostrum, milk, or baby pig serum.     

Trichinosis in a herd of swine: cannibalism as a major mode of transmission

In a herd of approximately 1,000 hogs, evaluation of muscle specimens collected at various intervals during a 12-year period (1973 to 1985) indicated continuous transmission of Trichinella spiralis. The farm's rat population and the incidence of trichinosis in the rats was high during 1974, but diminished markedly by 1978. In January 1984, a longitudinal investigation, using tracer pigs, was performed to determine whether rodents and/or other wild animals were involved in transmission of T spiralis on this farm. Tracer pigs exposed to rodents and wild animals did not become infected with T spiralis. The rodent population on the farm was small and none of the rodents trapped and examined were found to be infected. Hog cannibalism also was evaluated as a mode of T spiralis transmission. Results of the investigation indicated that hog cannibalism was the mode of transmission for trichinosis in the herd.