[Terminology for classifying the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds]. / Terminologie zur Klassifizierung des PRRSV-Status von Schweineherden.

Standardized terminology for the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds is necessary to facilitate communication between veterinarians, swine producers, genetic companies, and other industry participants. It is also required for implementation of regional and national efforts towards PRRSV control and elimination. The purpose of this paper is to provide a herd classification system for describing the PRRSV status of herds, based upon a set of definitions reflecting the biology and ecology of PRRSV. The herd classification system was developed by a definitions committee formed jointly by the American Association of Swine Veterinarians (AASV) and the United States Department of Agriculture PRRS-Coordinated Agricultural Project, and was approved by the AASV Board of Directors on March 9, 2010. The committee included veterinarians from private practice and industry, researchers, and representatives from AASV and the National Pork Board. Breeding herds, with or without growing pigs on the same premises, are categorized as Positive Unstable (Category I), Positive Stable (Category II), Provisional Negative (Category III), or Negative (Category IV) on the basis of herd shedding and exposure status. Growing-pig herds are categorized as Positive or Negative. Recommended testing procedures and decision rules for herd classification are detailed.

Types and doses of injectable medications given to periparturient sows.

OBJECTIVE: To determine types and doses of injectable medications given to periparturient sows and reasons for administering those medications, and to compare medication practices among farms of different sizes. DESIGN: Survey. SAMPLE POPULATION: 301 farms; 231,016 periparturient sows. PROCEDURE: A survey was used to obtain information regarding medications given to sows during the farrowing period. State and federal veterinary medical officers completed surveys during their final interview with producers who had participated in the National Animal Health Monitoring System's (NAHMS) Swine 95 study. Data were summarized and treatment regimens compared among farms of different sizes. RESULTS: More than a third of the sows received medications during the farrowing period. The most common reasons for administering medications were routine preventive treatment and treatment of dystocia, uterine discharge, and poor appetite. The most commonly used medications for treatment of sick sows were oxytocin, procaine penicillin G, and B vitamins. A high percentage of medications were either not indicated for the specific condition or used at greater or less than the approved dose. In general, treatment rates and medications used did not differ among farms of different sizes. CONCLUSIONS AND CLINICAL RELEVANCE: Better treatment protocols are needed to provide more appropriate treatment of sick sows.

Characterization of group C rotaviruses associated with diarrhea outbreaks in feeder pigs.

Feces and serum specimens were collected from three farms in Michigan on which approximately 50-lb (8- to 9-week-old) pigs experienced diarrhea just after placement into all-in-all-out finishing barns. The clinical signs (profuse watery diarrhea lasting about 2 weeks and no vomiting) were similar on all farms, and the morbidity rate was high (ranging from 60 to 80%) but without mortality. Eleven diarrheic fecal samples from the farms were tested for group A and C rotaviruses by immune electron microscopy (IEM) and various assays. IEM indicated that the fecal samples reacted only with antiserum against group C rotaviruses, and polyacrylamide gel electrophoresis indicated that the samples had characteristic genomic electropherotypes for group C rotavirus. Group C rotavirus was detected by cell culture immunofluorescence (CCIF) tests in nine fecal samples, but no group A rotavirus was detected by enzyme-linked immunosorbent assay or CCIF. By reverse transcription (RT)-PCR, all 11 fecal samples were positive for group C rotaviruses, with only 2 samples positive for group A rotaviruses. However, a second amplification of RT-PCR products using nested primers detected group A rotaviruses in all samples. Analysis of nucleotide and deduced amino acid sequences of the RT-PCR product (partial-length VP7) of the group C rotavirus showed 87.2 to 91% nucleotide identity and 92.6 to 95.9% amino acid identity among two strong samples from the different farms and the Cowden strain of porcine group C rotavirus. All nine convalescent-phase serum samples tested had neutralizing antibodies to the Cowden strain, and the majority of them had neutralizing antibody against group A rotaviruses (OSU or/and Gottfried strains) by fluorescent focus neutralization tests. Although group C rotaviruses have been reported as a cause of sporadic diarrhea in suckling or weanling pigs, to our knowledge, this is the first report of epidemic diarrhea outbreaks associated with group C rotavirus in older pigs.

Effects of extensive crossfostering on performance of pigs on a farm.

OBJECTIVE: To compare mortality and growth rates of pigs subjected to continuous or limited crossfostering. DESIGN: Prospective study. ANIMALS: 80 liters containing 879 pigs. PROCEDURE: In half of the litters, crossfostering was limited to the first 2 days of life. In the other litters, pigs were crossfostered throughout the lactation period to maintain uniform body weights within litters. RESULTS: Restricting crossfostering to the first 2 days of life resulted in a 20% increase in body weight at weaning, compared with crossfostering throughout the nursing period. Mortality rates did not differ between the limited and continuous crossfostering groups. CLINICAL IMPLICATIONS: The emphasis placed on reducing variation of body weights within litters is unwarranted and veterinarians should advise limiting crossfostering to the first 2 days of life. Excessive crossfostering late in the nursing period may be identified by low within-litter SD of mean body weight.

Patterns of crossfostering and piglet mortality on commercial U.S. and Canadian swine farms.

A data base of 300 farms using computerized records was used to examine the extent and timing of crossfostering being practiced in commercial herds in the Midwestern U.S. and Canada in 1994-1995. Crossfostering was used on 98% of farms. Across all farms, the mean percent of piglets crossfostered was 8.6%. Farms varied greatly in the age at which they moved piglets. The 20 farms that moved piglets the earliest after birth were classified as early-move farms and the 20 that moved the oldest piglets were classified as late-move farms. Early-move and late-move farms did not differ in herd size (P = 0.14), average parity of farrowed sows (P = 0.47) or age at weaning (P = 0.37). There were differences between early-move and late-move farms in percent of piglets fostered (P = 0.0001), pigs born alive/litter (P = 0.04), and pre-weaning mortality (P = 0.0005). A subset of late-move farms that were part of an integrated production group had unique production parameters that suggested inaccurate record-keeping.

Associations between off-label feed additives and farm size, veterinary consultant use, and animal age.

Data from the United States National Swine Survey collected by the National Animal Health Monitoring System were used to describe the use of feed additives in swine feeds. Data were collected from 710 farms. The concentration of feed additives expressed in grams per ton of complete feed was described by stage of production, and the use of feed additives above the labeled treatment levels (i.e. off-label) was identified. Of the 3328 feeds, about 79% contained feed additives used in the labeled manner. For all classes of pigs, the prevalence of labeled feed additive use was greater than 75%. Penicillin was used according to its label most often, followed by apramycin, bacitracin, tetracyclines, lincomycin, and tylosin. Carbadox had the highest prevalence of off-label use. Of the 699 feeds that included feed additives in an off-label manner, about 57% included additives at greater than the recommended concentrations or were fed to an incorrect class of pig. About 56% of the feeds had off-label combinations of additives. Small farms were more likely to use rations with no feed additives than intermediate or large farms (P < 0.001). Of those farms using feed additives, the odds of a small farm using all feed additives in the labeled manner was 7.7 times that of an intermediate or large farm (P < 0.0001). After controlling for herd size, producers who used a veterinary consultant were 2.1 times more likely to use feeds with feed additives (P < 0.0001).

Performance measured in pigs with pneumonia and housed in different environments.

During an investigation of poor growth performance, rate of weight gain and feed efficiency were studied in pigs with pneumonia. During the study, pigs either were housed in an improved environment or remained at their home farm. In both environments, rate of gain tended to decrease in association with increasing severity of pneumonia. When pigs with similar extent of lung lesions were compared, growth performance of pigs housed in the improved environment was better than that of pigs on the home farm. However, growth performance of pigs with pneumonia affecting greater than 20% of lung tissue was equally poor in either environment. When type of housing and extent of pneumonia were included in a model for analysis of variance, housing had a highly significant (P = 0.003) effect on rate of gain, and pneumonia had a nonsignificant effect.

Effect of Campylobacter spp-induced enteritis on growth rate and feed efficiency in pigs.

Diarrhea caused by Campylobacter spp-induced enteritis was observed in pigs that were part of a pneumonia study. Growth rate, feed conversion, and daily health status had been recorded for each pig in the trial. Because diarrhea was the only clinical sign of disease that developed in the control group of pigs, and no other diseases were detected in these pigs at slaughter, it was possible to examine the effect of diarrhea on growth rate and feed efficiency. During the course of the study, 6 of the 16 control pigs had severe diarrhea, 2 were moderately affected, and another 8 were slightly affected or remained clinically normal. Compared with the mean values for each pig, feed intake and daily weight gain were reduced in the week preceding the appearance of clinical disease, but not during the time when diarrhea was observed. Overall performance of pigs with severe diarrhea was not different from that of pigs that were not affected.

Antibody production and tissue irritation in swine vaccinated with Actinobacillus bacterins containing various adjuvants.

The effects that Actinobacillus pleuropneumoniae bacterins containing paraffin (mineral) oil, Al(OH)3, or lecithin-base oil adjuvants had on antibody production and muscle irritation were studied. Four hundred and thirty-two pigs were vaccinated twice (864 injection sites) at a 30-day interval. To assess effects of skin surface contamination on tissue reaction, 247 of the injections were made through skin soiled with manure. Serum samples for antibody determination and tissue samples were obtained at slaughter (15 to 90 days after vaccination). Bacterins containing Al(OH)3 or 5% lecithin-base oil as an adjuvant resulted in minimal tissue irritation. Bacterins containing paraffin oil or greater than 20% lecithin-base oil were more irritating to muscle, often resulting in a granuloma or an abscess at the injection site. Pigs given bacterins containing Al(OH)3 adjuvant had lower antibody titers than did pigs given bacterins containing paraffin oil or lecithin-base oil adjuvants.

Estimation of the cost of pneumonia in swine herds.

The data from studies of pneumonia, in which growth rate and feed conversion were measured, were examined with respect to the expected change in feed efficiency associated with a specific reduction in growth rate attributable to pneumonia in a swine herd. Information from 5 other studies was used to determine the expected reduction in growth rate that would be associated with the severity of pneumonia in the herd as determined by lesions recorded at slaughter. Together these calculations provide a reasonable estimation of the economic loss associated with pneumonia in a swine herd.

Interactions of management and animal performance in a swine feedlot.

The factors of feed efficiency, growth rate, carcass trim at slaughter, amount of antibiotic treatment, and death rate were compared among groups of pigs fed ("finished") in an open-front feedlot in Kansas. The factor having the greatest influence on performance was the month of entry of the pigs into the feedlot. Carcass trim at slaughter was greater in groups wherein each pig was given more than 4 ml of antibiotic than in groups wherein less than 4 ml of antibiotic was given to each pig. Death rates of pigs that remained in the feedlot longer than 150 days were nearly twice those of pigs that had been sent to slaughter before 150 days.

Comparison of tissue reactions produced by Haemophilus pleuropneumoniae vaccines made with six different adjuvants in swine.

Tissue damage caused by six different adjuvants incorporated in a Haemophilus pleuropneumoniae vaccine was compared in swine. The adjuvants compared were four mineral oil compounds, one peanut oil compound and aluminum hydroxide. Inoculations were given in the neck, quadriceps and semitendinosus muscles. The mineral oil adjuvants were highly irritant and caused extensive areas of granulomatous inflammation that were present at eight weeks after injection. The aluminum hydroxide produced smaller lesions that also persisted for eight weeks. Only the peanut oil adjuvant did not produce significant lesions at the site of injection. At two and four weeks, but not at eight weeks postinoculation, lesions in the quadriceps and semitendinosus muscles were approximately twice as extensive as those in the muscles of the neck.

Pneumonia and atrophic rhinitis in pigs from a test station--a follow-up study.

Pneumonia and atrophic rhinitis were studied for the second consecutive year in pigs at the same test station. Pneumonia was found to reduce mean daily gain by 3.3% for every 10% of the pig's lungs that had lesions. Atrophic rhinitis did not affect mean daily gain. There was no association between the development of atrophic rhinitis and the development of pneumonia. Pigs that were vaccinated with a Bordetella bronchiseptica bacterin did not have turbinate atrophy scores or mean daily gains different from those in pigs that were not vaccinated. Yorkshire and Hampshire pigs had higher prevalences and severity of pneumonia and atrophic rhinitis, compared with pigs of other breeds.

Causes and control of sow losses.

Pigs weaned/sow/year increases after the first litter to a maximum at about the third litter, after which it declines such that the sixth litter size is the same as the first, with a gradual decline thereafter. The cost of producing a weaned pig decreases with increasing numbers of litters weaned up to the third, then gradually increases. Average sow culling rates on commercial farms are 24-40% annually. The average time from weaning of pigs to culling of sows is 50-60 days. Sow mortality ranges between 2% and 14%, with a 6-8% average.

Factors affecting mortality in finishing pigs.

Two groups of finishing pigs at a test station were studied to test the effect of initial weight, weight change in the 1st week, age, breed, and distance the pig was transported on mortality. Total mortality was 5.3% in 1 group and 6.3% in the other group. Specific causes of death were pneumonia (24.7%), gastric ulceration (14.0%), enteritis (6.4%), trauma (4.3%), gastrointestinal displacement (4.3%), rectal stricture (3.2%), porcine stress syndrome (3.2%), and brain abscess (2.2%). Other categories for cause of death were miscellaneous (6.5%), and undiagnosed (31.2%). More pigs died in the last 6 weeks of the 18-week finishing period than in the 1st 6 weeks (P less than 0.05). Death rates were not significantly different between pigs that lost weight and pigs that maintained or gained weight during the 1st week after arrival at the test station. The mean transportation distance to the test station was not significantly different between pigs that died and pigs that survived. Transportation distance was not correlated with mean daily gain. The death rate was significantly (P less than 0.03) higher for Yorkshire pigs than for crossbred, Poland China, Hampshire, and Duroc pigs, and it was significantly (P less than 0.01) higher for Berkshire, Spot, and Chester White pigs than for Hampshire and Duroc pigs.

Traumatic pericarditis in a dog.

Signs of congestive heart faiure in a dog were caused by pericardial effusion and fibrous thickening of the epicardium and pericardium. Partial pericardiectomy and removal of the probable cause (shotgun pellets) resulted in recovery.