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

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, WAI, B169, Al 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

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

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

Erratum

Proposed revisions to the serologieal typing system for Treponema hyodysenteriae Table 2. Positive reactions shown between LPS from WAT. WA8 and WA12 and antiserum against B234 should have been with antiserum against B204 (i.e. in the adjacent column to the right)

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

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

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

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

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

Plasma oestrone sulphate (E1S) 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). E1S 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). E1S concentration was not an accurate predictor of litter size