The detection of porcine circovirus in the Australian pig herd

OBJECTIVE: To determine if porcine circovirus (PCV) type 1 (PCV1) or type 2 (PCV2) is present in the Australian pig herd, to conduct preliminary genetic characterisation of any viruses detected, and to determine if there is any obvious virological reason why post-weaning multisystemic wasting disease (PMWS), associated with PCV infection in other countries, has not been detected in Australia. DESIGN: Serum samples were collected from 14 randomly selected pig farms in Western Australia and used for detection of PCV antibody. Additional samples from one farm were obtained at 2-week intervals from pigs between 2 and 12 weeks of age to detect any age-associated variations in prevalence of infection. Veterinary practitioners from four Australian states submitted tissues of dead or unthrifty weaned pigs, and these were examined for evidence of PCV1 and PCV2 infection. PROCEDURE: Sera were tested for antibody to PCV using an indirect immunofluorescence assay (IFA). Tissues were tested for PCV1 and PCV2 genomic material using a multiplex PCR. RESULTS: PCV antibody was detected in approximately 30% of Western Australian pigs tested. PCV1 DNA was detected in tissue samples from Western Australia, South Australia and New South Wales and PCV2 DNA was detected in tissue samples from Western Australia, New South Wales and Queensland. Sequence analysis of the PCR products indicated the PCV1 and PCV2 present in Australia were very similar to strains in other countries where PMWS is endemic. CONCLUSION: Both PCV1 and PCV2 are present in Australia and the viruses present appear similar to those in countries with PMWS. The absence of PCV2-associated PMWS in Australia may be due to absence of essential secondary factors required for PCV2 to produce PMWS.     

Toxic effects of selenium on growing swine fed corn-soybean meal diets

A total of 96 crossbred pigs received various levels of sodium selenite to determine the effect of dietary selenium (Se) on growing swine fed corn-soybean meal diets. Levels of supplemental Se were 0, 4, 8, 12, 16 and 20 micrograms/g. There were linear decreases (P less than .01) in both gain and feed intake with increasing levels of dietary Se. Feed/gain increased numerically as dietary Se increased. Hair Se increased quadratically (P less than .01) and blood Se increased linearly (P less than .01) with increasing level of dietary Se. Cell volume and hemoglobin were not affected by dietary treatment. Increasing dietary Se significantly increased glutathione peroxidase (GSH-Px), glutamic-oxalacetic transaminase (GOT). and glutamic-pyruvic transaminase (GPT). External signs of selenosis were noted in some pigs fed 12 or 20 micrograms/g of Se. The toxic level of Se in a corn-soybean meal diet for crossbred pigs appears to be between 4 and 8 micrograms/g. Of variables studied, growth rate was the most sensitive indicator of chronic selenosis in swine.     

Clinical and hematologic variables in ponies with experimentally induced equine ehrlichial colitis (Potomac horse fever)

The clinical and hematologic variables of 10 ponies with experimentally induced equine ehrlichial colitis (EEC; syn: Potomac horse fever) were studied for a 30-day period (6 ponies) or until death (4 ponies). The earliest clinical sign indicative of EEC was fever (rectal temperature exceeding 39 C). All ponies became depressed (CNS) at various times during the disease, and 90% of the ponies developed diarrhea between 9 and 15 days after infection was induced. The most significant hematologic change was an increase in plasma protein concentration after the onset of fever (P less than 0.05). The PCV in all ponies became increased above base line during the diarrheic phase of EEC. Forty percent of the ponies developed anemia (PCV less than or equal to 23%) during the study. White blood cell counts were highly variable, with 80% of the ponies developing leukopenia (WBC less than 5,000/microliters) during the illness and 60% of the ponies developing leukocytosis (WBC greater than 14,000/microliters) after leukopenia was observed. Differential WBC changes varied widely and included neutropenia with a left shift, lymphopenia, and eosinopenia. Serial thrombocyte counts, which were done for only 1 pony, identified the development of marked thrombocytopenia. Some hematologic changes in ponies with EEC were similar to those reported in canine monocytic and equine granulocytic ehrlichioses. These data are discussed in the context of the pathogenesis and differential diagnosis of EEC.