Peter D. Cockcroft

Handbook of evidence-based veterinary medicine.

Preface Acknowledgements 1. Introduction 2. Turning Information Needs into Questions 3. Sources of Information 4. Searching for Evidence 5. Research Studies 6. Appraising the Evidence 7. Diagnosis 8. Clinical Diagnostic Decision Support (CDDSSs) 9. Decision Analysis, Models and Economics as Evidence 10. EBVM: Education and Future Needs Glossary Bibliography Answers to Review Questions Index

Handbook of Pig Medicine

Preface Dedication Acknowledgements 1. Clinical examination of the pig 2. Pig population medicine 3. Diseases of the musculoskeletal system 4. Diseases of the respiratory system 5. Diseases of the gastrointestinal system 6. Diseases of the skin 7. Diseases of the central nervous system 8. Diseases of the cardiovascular system 9. Diseases of the urogenital system & udder 10. Reproduction & obstetrics in the pig 11. Polysystemic diseases 12. Outdoor & organic pigs 13. The pet pig 14. Antimicrobial therapeutics 15. Anaesthesia, analgesia & surgical procedures in the pig 16. Sampling, euthanasia & post mortem examination of the pig 17. Haematology & biochemistry of the pig 18. Differential diagnosis in the pig Appendices i) Notifiable diseases in the pig ii) OIE group a & b pig diseases iii) Bibliography Index

Evidence-based veterinary medicine 1. Why is it important and what skills are needed?

THIS is the first part of a series of three articles on evidence-based veterinary medicine (EBVM) - a discipline which increasingly is being recognised as having a fundamental role to play in day-to-day veterinary practice, as well as being vital to the future development of the profession. The article defines what EBVM is, explains its importance and describes the range of skills required to practise EBVM. Parts 2 and 3, which will be published in the February and March issues, respectively, will look in greater detail at first identifying information needs and searching for evidence, and then appraising the evidence.

Controlled clinical trial of the effect of a homoeopathic nosode on the somatic cell counts in the milk of clinically normal dairy cows

Cows in a 250-cow Holstein-Friesian herd were allocated at random to be treated with either a homoeopathic nosode or a negative control, both treatments being applied by means of an aerosol spray to the vulval mucous membranes. A total of six treatments were given over a period of three days and milk samples were taken for the determination of somatic cell counts (SCC) on days –3, 3, 7, 9, 14, 21 and 28. Individuals applying the treatments or carrying out the SCC determination were unaware of which animals were receiving which treatment. Owing to the wide natural variations in SCC, the trial had only a 71 per cent possibility of detecting a 30 per cent difference in SCC between the two groups. There were no significant differences between the SCC of the two groups on any sample day, but there were significant variations between the SCC on different days (P=0·003) in both groups.

Evidence-based veterinary medicine 2. Identifying information needs and finding the evidence

THE first article in this three-part series (In Practice, January 2004, pp 28-33) explained the importance of evidence-based veterinary medicine (EBVM) and described the range of skills required to practise it. The first step in the process of EBVM is to identify information needs and translate these needs into scientific questions. This article discusses how to do this, as well as how to locate sources of evidence and then search for evidence. Part 3, to be published in the next issue, will be concerned with appraising the evidence.

Comparison of serum, ear notches, and nasal and saliva swabs for Bovine viral diarrhea virus antigen detection in colostrum-fed persistently infected (PI) calves and non-PI calves

The diagnosis of neonatal and young calves persistently infected (PI) with Bovine viral diarrhea virus (BVDV) by antigen-capture enzyme-linked immunosorbent assay (ACE) may be complicated by interference from colostrum-derived specific antibodies. Ten calves, with 3 calves identified as PI and 7 as non-PI were used in the current study. All non-PI calves were shown to be seropositive for BVDV-specific antibodies by antibody enzyme-linked immunosorbent assay (Ab-ELISA) on serum. Serum samples, ear notch samples, and nasal and saliva swabs were collected from each calf from birth until 12 weeks of age and tested by ELISA for BVDV-specific antigen and antibodies. Following colostrum ingestion, Ab-ELISA sample-to-positive (S/P) ratios rose by a mean of 0.95 (95% confidence interval [CI] = 0.64–1.25) and 1.72 (95% CI = 1.55–1.89) in seropositive, non-PI calves and in PI calves, respectively. The mean S/P ratios then declined to approximately 1.1 in non-PI calves and 0.5 in PI calves at between 60 and 80 days of age. In PI calves, testing for antigen in serum and nasal and saliva swabs was subject to interference by colostrum-derived antibodies in calves up to 3 weeks of age. Nasal swabs were less affected than serum and saliva swabs. Ear notches maintained positive ACE corrected optical densities at all sample times, despite a drop in the signal following the ingestion of colostrum.

Clinical examination of the pig

THE nature of the pig, which characteristically will squeal and run away if frightened, may suggest that an effective clinical examination is difficult, if not impossible. However, a patient and calm approach, and use of appropriate restraint techniques, will usually overcome these defence mechanisms and allow a meaningful clinical examination to be carried out. This article describes the observations and physical examination that may be performed as part of the clinical assessment of an individual sick or injured pig. Illustrations and notes of specific conditions, abnormalities and findings that may be encountered are included, with the intention of providing a clinical checklist for the inexperienced practitioner. A previous In Practice article described other elements of the investigation of clinical problems on pig farms (Green 1999).

Erysipelothrix rhusiopathiae and Mycoplasma hyopneumoniae: the sensitivities of enzyme-linked immunosorbent assays for detecting vaccinated sows of unknown disease status using serum and colostrum, and the correlation of the results for sow serum, colostrum, and piglet serum.

Due to relatively high concentrations of immunoglobulins, colostrum has the potential to improve the sensitivity of diagnostic tests for diseases in pigs when compared with serum. It is possible that colostrum could improve the sensitivity of the antibody enzyme-linked immunosorbent assay (ELISA) compared with serum. Colostrum is also essential for piglets, providing protection against infections in the first few weeks and months of life. The sensitivity of 2 commercially available ELISAs, one for the detection of Erysipelothrix rhusiopathiae and the second for Mycoplasma hyopneumoniae antibodies, when used with sow colostrum in comparison with serum was investigated. The correlation of maternal E. rhusiopathiae– and M. hyopneumoniae–specific antibody levels with specific-antibody serum levels in the piglet was also determined. The sensitivity was defined as the proportion of vaccinated sows that were correctly identified as vaccinated at a given cutoff point. The true disease status of the sows with regard to the 2 infections was unknown. Blood and colostrum samples were collected from 20 sows, 10 primiparous and 10 multiparous, and blood samples were also collected from the piglets of each sow, 48–72 hr post-farrowing. The sensitivities of both ELISAs were significantly improved when using colostrum compared with serum. Sow serum and colostrum optical density (OD) values were significantly correlated. The mean sow OD values for serum for E. rhusiopathiae and M. hyopneumoniae and colostrum for E. rhusiopathiae were significantly correlated with piglet serum OD levels. If the improved sensitivity of colostrum can be demonstrated in infected animals, this will increase the ability of the test to identify infected animals using both individual and pooled colostrum. Testing serum and/or colostrum using ELISA can be useful predictors of piglet disease–specific OD values.

Serological survey for antibodies against bovine viral diarrhoea virus and Neospora caninum in a population of South Australian alpacas (Vicugna pacos).

OBJECTIVE Bovine viral diarrhoea virus (BVDV) and Neospora caninum may cause clinical disease in alpacas. Both diseases are present in the Australian cattle population. The objective of this study was to perform a serological prevalence survey for BVDV and N. caninum exposure in a regional alpaca population of South Australia. METHODS Serum samples were taken from 182 alpacas on 10 farms, which had a combined population of 1308 alpacas. Serological analysis for BVD antibodies was performed using a competitive BVDV antibody ELISA kit. Serological analysis for N. caninum was performed using an anti-Neospora ELISA with a protein G conjugate. RESULTS Of the 182 alpacas sampled, 5 animals located on three properties were positive for BVDV antibodies, constituting a prevalence of 2.7% (95% confidence interval 1-6%). All samples tested negative for N. caninum antibodies. CONCLUSION There is a low BVDV seroprevalence and N. caninum is currently either absent or present at a very low prevalence in this population of alpacas in South Australia. There is serological evidence for the presence of both organisms in South Australian beef and dairy cattle herds. Appropriate biosecurity protocols to minimise the risk of introduction and exposure should be a high priority to maintain this favourable status.

Clinical examination of the abdomen in adult cattle

CLINICAL examination of the abdomen in adult cattle can be daunting due to the fractious nature of infrequently handled animals and the lack of adequate restraint facilities on some farms. For many veterinary surgeons, cattle have become an unfamiliar species which are only examined periodically. The range of abdominal conditions which may occur in cattle is challenging and a careful cost-benefit analysis is required before an investigative or treatment protocol in embarked upon. Nevertheless, much can be achieved by using a methodical approach and many conditions may be successfully (and dramatically) treated if the correct diagnosis is achieved. This article describes how to conduct a systematic clinical examination of the bovine abdomen and outlines the abnormalities which may be found. In particular, it considers the observation and examination of the patient and any further diagnostic investigations which may be useful. Where appropriate, specific conditions are used to illustrate the abnormalities which may be present. The urogenital system is not covered.