Student training in large-animal handling at the School of Veterinary and Biomedical Sciences, Murdoch University, Australia.

The ability to handle animals safely, competently, and with confidence is an essential skill for veterinarians. Poor animal-handling skills are likely to compromise credibility, occupational health and safety, and animal welfare. In the five-year veterinary science degree at Murdoch University, animal handling is taught in a prerequisite unit in the second semester of the second year. From 2008, however, this unit will be taught in the first year of the five-year course. Students are taught to handle sheep, cattle, pigs, and horses safely and competently. Each student receives 30 hours of formal practical instruction. Animal-to-student ratios are 2:1, and staff-to-student ratios vary from 1:8 (sheep, cattle, horses) to 1:17 (pigs). Students must pass the practical exam to proceed into third year. Additional experience with animals is gained during third year (14 hours of practical instruction with sheep, goats, pigs, and cattle) and during the 5 weeks and 2 days of vacation farm experience during the second and third years. In the fourth and fifth years, students consolidate their handling experience with sheep (including rams), goats, pigs, cattle (including bulls), horses (including stallions), and alpacas. As a result, students are able to handle and restrain client animals with confidence. There is no formal course in small-animal handling at Murdoch University. Factors that have enhanced the success of the large-animal handling program include purpose-built on-campus facilities. Inadequate resources (time, facilities, and animals) remain the main impediment to effective learning, further compounded by the increasing tendency of university administrators to make decisions based on economic expediency rather than educational benefit.

Genetic characterisation of Australian strains of porcine circovirus types 1 and 2.

OBJECTIVE: As post-weaning multi-systemic wasting syndrome (PMWS) has not been identified within Australia, to determine if the absence of disease was associated with genetic differences between the strains of porcine circovirus (PCV) present in Australia and those from countries in association with PMWS. DESIGN: Pig tissues were obtained from weaned pigs found dead or presenting with clinical signs of illthrift and also from neonatal pigs with congenital tremors and used as a source of virus DNA for sequence analysis. PROCEDURE: DNA was extracted from the tissues and PCV detected by polymerase chain reaction (PCR). PCR with PCV type-specific primers was used to amplify the entire genome from selected tissues. The genomes of three strains of PCV1 and seven strains of PCV2 from three Australian states were sequenced and subjected to phylogenetic analysis using standard procedures. RESULTS: The three Australian PCV1 strains had 98 to 99% nucleotide identity to strains in other countries and the seven Australian PCV2 strains had 94 to 99% identity to PCV2 strains in other countries where PMWS has occurred. Six of the seven Australian PCV2 strains were genetically similar to each other, while the seventh was more distantly related. There were no consistent differences in the predicted amino acid sequence of the Australian strains of PCV2 and strains associated with PMWS in other countries. CONCLUSION: There were no consistent differences between Australian strains of PCV and those that have been associated with PMWS in other countries and it appears likely that other factors are responsible for the absence of PMWS in Australia.

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.

Enzootic pneumonia of pigs--a diagnostic dilemma.

In an enzootic pneumonia-free Australian pig herd, an outbreak of a severe respiratory disease in the grow-out herd was initially diagnosed as acute tracheitis and pneumonia precipitated by the dusty environment, with a superimposed mixed infection of Pasteurella multocida and Arcanobacterium pyogenes. Culture for Mycoplasma hyopneumoniae, Salmonella sp and fungi was negative. The outbreak persisted. Subsequently, gross lesions consistent with enzootic pneumonia occurred, but histological lesions were equivocal and definitive tests for M hyopneumoniae remained negative. Eighteen months after the initial outbreak, gross and histological lesions were consistent with enzootic pneumonia but serological tests were still negative. Almost 2 years later, one of four nasal swabs was positive by the polymerase chain reaction test for M hyopneumoniae, and then lung samples were sporadically positive. The pneumonic disease became endemic in the herd. Gross lesions consistent with enzootic pneumonia occurred in another herd belonging to the same company nearly 2 years after the initial outbreak. Again, results of laboratory tests were inconsistent. Despite sporadic positive polymerase chain reaction tests for M hyopneumoniae, the respiratory disease resolved within 4 months and there has been no clinical evidence of enzootic pneumonia during the subsequent 4 years. These cases raise important questions about the role of the diagnostic tests and their interpretation, and the ecology of M hyopneumoniae and its role in enzootic pneumonia.

Identification of a novel Cryptosporidium genotype in pigs.

Over a 3-year period, a total of 646 fecal samples from pigs in 22 indoor and outdoor herds from Western Australia were screened for Cryptosporidium spp. by microscopy. Results revealed that 39 of 646 samples (6.03%) were positive for Cryptosporidium. Cryptosporidium was much more common in outdoor herds (17.2%) than in indoor herds (0.5%) and was more common in animals between the ages of 5 and 8 weeks (69.2%) than in younger animals (P < 0.0001). Molecular characterization of the positive samples at the 18S ribosomal DNA locus identified two distinct genotypes of Cryptosporidium: the previously identified pig genotype I and a novel pig genotype (pig genotype II), both of which warrant species status.

T cell transduction and suicide with an enhanced mutant thymidine kinase.

Retroviral transfer of Herpes simplex virus thymidine kinase to T cells has been used to confer sensitivity to the antiviral agent ganciclovir. This has allowed therapeutic approaches to be developed in which T cells mediating graft-versus-host disease after bone marrow transplantation can be selectively eliminated by the administration of ganciclovir. Although the strategy has been shown to be generally successful in early clinical trials, there are concerns about possible resistance to ganciclovir and the risk of myelosuppressive side-effects at the doses required to induce T cell suicide. We have incorporated the enhanced mutant HSV-TKSR39 into retroviral vectors tailored to exhibit high levels of expression in T cells and have used protocols optimized for the transduction and selection of primary lymphocytes. We demonstrate that leukemic and primary T cells can be efficiently transduced and highly enriched under conditions that should be readily adaptable for clinical use. T cells carrying HSV-TKSR39 were inhibited by exposure to ganciclovir at concentrations an order of magnitude below those required for wild-type HSV-TK. The less toxic agent aciclovir also eliminated T cells transduced with HSV-TKSR39 (but not HSV-TK), underlining the increased therapeutic potential of the mutant suicide gene system in the bone marrow transplantation setting.

Neonatal dendritic cells are intrinsically biased against Th-1 immune responses.

Dendritic cells (DCs) were derived from human peripheral blood monocytes or cord blood monocytes cultured in the presence of IL-4 and GM-CSF. Adult and cord DCs were observed to have comparable immature phenotypes. However, the increase in surface expression of HLA-DR and CD86 after addition of LPS was significantly attenuated in cord DCs, with CD25 and CD83 expression also markedly reduced. Cord DCs were also unable to produce IL-12p70, failed to down-regulate expression of the chemokine receptor CCR5 and induced lower levels of IFN-gamma production from allogeneic naive CD4+ T cells than their adult counterparts. In contrast, the kinetics of the production of TNF-alpha and IL-10 in response to LPS stimulation was comparable to adult DCs. The reduced ability of cord DCs to attain a fully mature adult phenotype, and to activate naive CD4+ T cells to produce IFN-gamma, suggests that they are intrinsically preprogrammed against the generation of Th-1 immune responses.

Heat shock protein-56 is induced by cardiotrophin-1 and mediates its hypertrophic effect.

Cardiotrophin-1 (CT-1) is an interleukin-6 family cytokine with known protective and hypertrophic effects in the heart. Previous studies have shown that CT-1 treatment increases heat shock protein 70 (hsp70) and heat shock protein 90 (hsp90) levels in cardiac cells. Due to the known protective effects of hsp90 and hsp70, induction of these proteins may be involved in the protective effects of CT-1. We show here that heat shock protein 56 (hsp56), also known as FK506 binding protein 59 (FKBP59), is induced by CT-1 treatment at both the mRNA and protein levels. It has been demonstrated previously that, unlike hsp70 and hsp90, hsp56 overexpression does not protect cardiac myocytes against stressful stimuli. The other known effect of CT-1 is hypertrophy, an increase in cell size without cell division, which occurs in many cardiac pathologies. We investigated the role of hsp56 in the hypertrophic response of primary neonatal rat cardiac myocytes, using overexpression with transiently transfected plasmid vectors and Herpes viral vectors. Overexpression of hsp56 caused a significant increase in cardiac cell size and protein:DNA ratio. Hsp27, hsp70 and hsp90 overexpression had no effect on cell size. An antisense construct to hsp56 reduced hsp56 levels when transiently transfected and blocked the hypertrophic effect of CT-1. This is the first time that a hypertrophic effect has been demonstrated for a heat shock protein and demonstrates that CT-1-induced hypertrophy involves a specific hsp, which is not involved in its protective effect.

Evaluation of a novel antimicrobial polymer for the control of porcine postweaning colibacillosis.

OBJECTIVE: To determine whether CHEMYDERTM polymer has potential for use in the control of porcine postweaning colibacillosis (PWC). PROCEDURE: Two experiments were conducted in which 50 young pigs, either receiving CHEMYDERTM polymer in their food or not, were challenged orally with cultures of beta-haemolytic Escherichia coli immediately after weaning. Their response in terms of development of diarrhoea, and the extent of colonisation of the intestinal tract by the bacteria was monitored. In a third experiment CHEMYDERTM polymer was added to the water supply of a group of 15 pigs on a piggery where PWC was an ongoing clinical problem. The response of these pigs was compared with that of pigs vaccinated against PWC or left unmedicated. RESULTS: In both experimental infection trials the pigs receiving CHEMYDERTM polymer showed significantly reduced intestinal colonisation with the challenge strain of E coli, and, in trial 2, significantly less diarrhoea after weaning compared to pigs not receiving CHEMYDERTM polymer. In the field trial the pigs receiving CHEMYDERTM polymer had significantly less diarrhoea and required significantly less antibiotic treatment than the other two groups of pigs. CONCLUSION: CHEMYDERTM polymer has potential for use in the control of PWC.

Molecular and biological characterisation of Cryptosporidium in pigs.

OBJECTIVE: Genetic and biological characterisation of 12 isolates of Cryptosporidium from pigs and comparing them with Cryptosporidium isolates from humans and cattle. DESIGN: Cryptosporidium isolates from pigs were compared with those obtained from human and cattle using rDNA sequence analysis. The infectivity of two of the porcine isolates was determined in neonatal mice and the clinical history of the infected pigs recorded. RESULTS: Pig-derived isolates of Cryptosporidium exhibited two distinct genotypes; a porcine genotype and a bovine genotype, which is common to cattle and other livestock. The porcine genotype did not produce any infection in neonatal mice whereas the bovine genotype did. CONCLUSION: Two distinct genetically and biologically differing strains of Cryptosporidium appeared to be associated with acute diarrhoea in pigs. Whether Cryptosporidium was a primary or secondary pathogen is unclear but warrants further investigation. As the bovine genotype is known to infect humans, the results suggest that pigs can act as reservoirs of cryptosporidial infections for humans and other live-stock. The zoonotic potential of the pig-adapted genotype is uncertain and requires further study.

Epidemiological studies of pig diseases: 1. Use of French protocols for risk factor assessment to predict the health status of Australian herds.

OBJECTIVE: To determine in Australian pig herds the accuracy of French protocols for risk factor assessment. PROCEDURE: Data on health indicators and risk factors were collected for three syndromes, 'pre-weaning diarrhoea', 'post-weaning diarrhoea' and 'respiratory problems', using the French protocols. The protocols were used on 118 occasions in 32 Western Australian pig herds during 3 years (1988 to 1991). RESULTS: There was a wide variation in pre-weaning performance, for example growth rate was 107 to 273 g/day (< 200 g/day in 33% of herds). Respiratory lesions at weaning were associated with poor pre-weaning performance. Post-weaning (21 days after weaning) growth rate was 114 to 408 g/day (< 250 g/day in 54% of herds). In the grower herds, 91% of herds had pneumonia, and growth rate was 439 to 625 g/day (< 550 g/day in 54% of herds). Pleurisy as well as pneumonia was associated with reduced growth rate. The risk factor most closely associated with respiratory health status was air volume per pig. CONCLUSION: Risk factors were most accurate at predicting the health status in post-weaning problems. A weaning weight of at least 7.9 kg and weaning age of 30 days optimised weaner performance. Stocking densities and shed designs providing at least 3 m3 air volume and 0.6 m2 floor space per pig throughout the growing phase should be considered for an improved respiratory health status. Australian pig sheds often do not provide a satisfactory environment for optimum health. The technique of risk factor assessment as an aid to the maintenance of health in pig herds is applicable in Australia, but further research is necessary to determine the most important Australian risk factors.

Epidemiological studies of pig diseases: 2. Post-weaning diarrhoea and performance in Western Australian pigs.

OBJECTIVE: To determine in Australian pig herds the accuracy of French protocols for risk factor assessment of post-weaning diarrhoea and illthrift. PROCEDURE: French protocols for the collection of data on health indicators and risk factors for post-weaning diarrhoea were conducted on 54 batches of weaner pigs from 28 Western Australian pig herds during three years. RESULTS: Large variations in post-weaning performance were found. About one-third of the batches were growing at < 200 g/day during the 3 weeks after weaning, and 54% had growth rates of < 250 g/day. Weaning age and weight of at least 30 days and 7.9 kg, respectively, optimised weaner performance. Other risk factors associated with little post-weaning diarrhoea and good weaner performance were high creep feed intakes, relatively little diarrhoea as suckers, and, contrary to expectations, large temperature fluctuations. CONCLUSION: Overall, the 'predictability' of post-weaning problems as assessed by measurement of risk status, was good. However, the model was less accurate at predicting the performance of a single batch of pigs.

A problem-solving format for written examinations in veterinary clinical subjects.

A simple format for a problem-solving written examination for testing students in clinical subjects was devised. A clinical problem was divided into several parts, which were described on separate pieces of paper. Students answered one part at a time, and then proceeded to the next part on which earlier relevant information was retained. The format requires students to recall, collate, analyse, interpret and synthesise information; it has been used successfully for seven years, and has potential as a teaching method.

Typing of Treponema hyodysenteriae by restriction endonuclease analysis.

Restriction endonuclease analysis (REA) was used to type eight well-characterised strains of Treponema hyodysenteriae originating from the U.K., Canada and the U.S.A., and 16 isolates from cases of swine dysentery in Western Australia (W.A.). Several of the W.A. isolates were also serotyped by the method of Baum and Joens (1979), and the two typing techniques were compared. REA typing was more discriminatory than serotyping, being able to distinguish strains within serotypes. The new technique was neither more difficult nor more time-consuming to perform than serotyping. Within the 16 W.A. isolates, three different REA patterns were identified, with common patterns found on different farms. The eight overseas strains had seven different REA patterns, all of which could be distinguished from the patterns of the W.A. isolates.

Proposed revisions to the serological typing system for Treponema hyodysenteriae.

Antisera were prepared in rabbits against seven well-characterized strains of Treponema hyodysenteriae of known serotype, and reacted in agarose gel double immunodiffusion tests (AGDP) with lipopolysaccharide (LPS) extracted from 18 Western Australian isolates of the organism. Eight isolates were provisionally typed by this method, but sera raised against one 'typed' and two 'untypable' local isolates reacted in an unexpected fashion with LPS from other local and type strains. Serum raised against the 'typed' local isolate reached with LPS from other previously untyped local isolates: this indicated the presence of more than one major LPS antigen amongst certain local isolates, and was confirmed by cross-absorption of sera. Sera raised against apparently untypable local isolates reacted with LPS from certain type organisms, thus suggesting the presence of complex antigenic relationships between LPS antigens. The serotyping system for T. hyodysenteriae which was proposed by Baum & Joens (1979) uses unabsorbed antisera and is made unworkable by these observations. Instead we propose placing organisms which share common LPS antigens into serogroups A to E, members of which are defined by their reactivity with unabsorbed sera raised against a type organism for the group. We suggest strains B78, WA1, B169, A1 and WA6 respectively as being the most suitable type organisms for the five serogroups identified so far. Isolates possessing additional unique LPS antigens can be regarded as serotypes within the serogroup. However the serotype of an isolate can only be established if antiserum is prepared against it, and this serum continues to react homologously after cross-absorption with bacteria from other serotypes within the serogroup.

A comparison between plasma oestrone sulphate concentration and doppler ultrasound as methods for pregnancy diagnosis in sows.

Plasma oestrone sulphate (E(1)S) concentration and doppler ultrasound as methods of pregnancy diagnosis in sows were compared. Using either method, pregnancy was accurately detected (test sensitivity > 94% for pregnant sows). E(1)S was a better predictor of nonpregnant animals (test specificity 78 vs 66%, respectively; P < 0.01) and could be used at least 1 wk earlier than doppler ultrasound (24 to 30 d vs 35 d postservice, respectively). E(1)S concentration was not an accurate predictor of litter size.

The occurrence of antibiotic resistance in Clostridium perfringens from pigs.

Porcine faecal specimens were collected from piggeries in south western Australia. Clostridium perfringens strains were isolated, identified, and examined by disc susceptibility tests for their resistance to several antibiotics. The resultant data were correlated with the known exposure of the animals to antimicrobial agents in the feed or water. The results showed that the percentage of C. perfringens isolates resistant to tetracycline or the macrolide-lincosamide antibiotics was significantly higher from weaners fed one of a number of combinations of antimicrobial agents than was the percentage of resistant strains isolated from the one piggery that did not use antimicrobials. No differences in the levels of chloramphenicol or penicillin resistance were observed. Genetic analyses showed that 3 of the resistant strains carried conjugative R-plasmids which carried the tetracycline resistance determinants.