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Pig Journal Volume: 44
Publication date: November 1999

Refereed Section

A STUDY INVESTIGATING EPIDEMIOLOGICAL RISK FACTORS FOR PORCINE CIRCOVIRUS TYPE II IN ONTARIO
T.S. Cottrell, R.M. Friendship, C.E. Dewey, G. Josephson, G. Allan, I. Walker, F. McNeilly

Abstract
A cross-sectional study involving 25 Ontario farms was undertaken in order to investigate the epidemiological risk factors for Porcine Circovirus type II in Ontario. Each farm was visited on a single occasion and three poor-doing pigs were sacrificed for post-mortem examination. Tissue samples were taken for both Polymerase Chain Reaction and immunohistochemistry. A random sample of sows and eight-week-old pigs were blood-sampled and tested for PCV II antibody using an indirect immunofluorescence technique (IIF). A survey was completed by the producers addressing biosecurity, nursery management, nursery facilities, and mortality records. Possible risk factors were analysed using the Fisher's exact test, Student's t-test, and all results were compared at the farm level. Infected farms had more nursery-pig diseases, and lower biosecurity scores than non-infected farms.

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Proceedings Section

This section includes the Proceedings of the Pig Veterinary Society meeting held at the Hilton Hotel, Birmingham, on 15th and 16th April 1999

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ASSESSING PUBLIC ATTITUDES TOWARDS PIG WELFARE IN THE UK
I.A Holloway, N. Waren, E.J. Austen

Abstract
Public concern for farm animal welfare in the UK appears to be well established and widespread. However, current problems in the UK Pig Industry suggest that consumer opinion may not correlate with consumer behaviour. If the current propensity towards welfare-friendly food animal products in shops is to be effective, it is imperative to understand the knowledge and attitudes of consumers pertaining to animal welfare, and to ascertain how much they would be prepared to pay for the cost of welfare improvements. This paper describes a questionnaire survey of 160 members of the general public. Its purpose was to investigate people's knowledge of, and opinions towards, pig welfare; their willingness to pay for three alternative systems (indoor straw, out/in, outdoor) of pig production and this was assessed using the contingent valuation technique. The results indicate that the public knows relatively little about pig farming and welfare issues. Two distinct attitudes (efficiency and concern) were apparent; but these were not mutually exclusive and appeared to be held concurrently amongst individuals. Willingness to pay was high amongst respondents (80%), but bid level varied according to attitude. It is suggested that such results should be interpreted with caution, as consumers may have conflicting ideas about animal (pig) welfare that affect their willingness to pay for it and that this could be addressed by increasing consumer awareness of the relevant issues.

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LOW COST PIG MEAT PRODUCTION
J.S. Richardson

Abstract
The UK pig producer supplies pig meat into the EU market, a more global market is imminent. In order to ensure viability of individual enterprises during periods of market over supply it is essential that the break-even cost of production is minimised. There are many factors which combine to influence this cost - this review explores some of them.

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PRODUCTION DISEASES
N.G. Kingston

Abstract
The term 'production disease' is a common term in pig production; but it is a poorly defined entity. In this paper, production disease is defined as the factors that decrease the pig's ability to perform to the maximum of its genetic potential. Principally, these are stockmanship, housing, hygiene, the production or hygiene system adopted on the farm and the overall disease status of the unit. In the feeding herd, production disease is principally related to the level of infectious organisms that challenge the animals immune system and is principally management related.

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SALMONELLA IN PIGS: AN UPDATE
J.R. Thompson, K.E. Armstrong, J.C. Low

Abstract
Recent figures for salmonella isolations in pigs in the UK showed that Salmonella typhimurium is most prevalent, followed by Salmonella derby, together comprising 79% of all isolates from 1996 to 1998. The three main Salmonella typhimurium definitive types are DT 104, DT 193 and DT 208. S. typhimurium DT 104 has shown a steady increase in prevalence since 1990. Sweden and Denmark both operate an eradication policy for S. typhimurium DT 104 and salmonella control schemes aimed at minimising the prevalence of salmonella infection on pig farms. Use of the Danish Salmonella "mix-ELISA" test and the feasibility of introducing a salmonella control scheme into the UK pig industry are discussed.

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THE RESPONSIBLE USE OF MEDICINES
C.E. Glossop

Abstract
This paper reviews the use of medicines in the animal health field, their impact on public health, and the responsibilities of veterinary surgeons in relation to both. The ethics and practicalities of professional involvement are highlighted and sensibly discussed.

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THE HACCP CONCEPT: A UNIFYING APPROACH TO THE PRODUCTION OF SAFE FOOD
G.C. Mead

Abstract
The Hazard Analysis Critical Control Point (HACCP) approach is a systematic means of identifying foodborne hazards, whether microbial, chemical or physical, assessing their significance and implementing appropriate control measures. It involves the use of a monitoring system that can detect any loss of control in a food production, processing or handling operation, and provide the necessary information in time for corrective action to be taken before any need to reject the product. Successful application of HACCP principles requires personnel to be trained in basic food hygiene and use Good Manufacturing Practices in order to create a suitable working environment for safe food production. A particular advantage of the HACCP system is its universal applicability throughout the entire food chain, although the development of HACCP programmes for farms is still at an early stage. Thus, the HACCP concept is the key to a true "farm to fork" strategy for food safety control. When properly applied, it will help the food industry to meet its commitments to the public and will benefit the consumer by ensuring a food supply that achieves the highest attainable standards of product safety.

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CORRELATION OF THE PRESCRIBING OF ANTIMICROBIAL AGENTS TO THE DEVELOPMENT OF RESISTANCE IN BACTERIA AFFECTING A HUMAN POPULATION
J.A. Birkin, M.C.J. Wale

Abstract
Bacteria have developed or acquired resistance to antibiotics since their introduction in the 1940s. The prevalence of resistant bacteria is increasing rapidly, leading to decreasing efficacy of antibiotics. Further escalation will inevitably lead to increased rates of morbidity and mortality, with the resulting inflation of health care costs. Antimicrobial resistance therefore is high on both the political and public health agendas. This paper seeks to address this problem.

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REPORT ON A VISIT MADE TO DENMARK ON BEHALF OF THE PIG VETERINARY SOCIETY, JANUARY 26-28, 1999
J.D. MacKinnon

Abstract
Following their rebuttal of assertions that 'foreign' pig meat on sale in the UK was inferior, in terms of welfare and production, to the home-bred product, the Danish Bacon and Meat Council (DBMC) invited a delegation from Britain to inspect and assess current Danish farming practices. The invitation was accepted and nine British delegates visited Denmark to review the situation. This Report collates their findings.

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RISK ANALYSIS AND RISK ASSESSMENT IN PIG PRODUCTION
L. Kelly, M Wooldridge

Abstract
During the last five or so years, the use of risk analysis and risk assessment has expanded within the veterinary domain. Early analyses have focused on issues relating to international trade and have been concerned primarily with import/export problems. More recently, topics such as food safety and disease transmission have been approached from a risk analysis perspective and consequently these tools are becoming recognised as a useful aid to decision making in all areas of animal production. This paper gives an overview of risk analysis and risk assessment. Initially, the terminology and methodology used are outlined. The use of these techniques is then demonstrated by considering some examples from pig production.

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THE ASSESSMENT OF CLINICAL DISEASE SEVERITY IN PIGS INFECTED WITH ACTINOBACILLUS PLEUROPNEUMONIAE
L. Reeve-Johnson, A. Hodge, J. Otte

Abstract
In the European Union the licensing of medicinal products is regulated by a series of Directives intended to ensure the thorough assessment of the quality, safety and efficacy of products (Reeve-Johnson, 1997). The assessment of clinical efficacy is the most subjective and least well-defined aspect of the product registration procedure. While MIC and pharmacokinetic data provide an impression of likely efficacy, the true behaviour of drugs can only be proven by in vivo studies (Reeve-Johnson, 1997; 1998). However, clinical assessments of disease severity in vivo are often subjective, the hypothesis under investigation was that these correlate with the pathological progression of disease in the animal. Assessing the severity of a disease can also be important in understanding its economic impact. Whilst discrete numeric values can be assigned to the prevalence and incidence of disease within a given population, the quantification of clinical severity is more difficult to express. A variety of objective and subjective assessments of disease severity collected ante-mortem and post-mortem were correlated from 30-40 kg pigs, infected with Actinobacillus pleuropneumoniae (APP). These data provide an indication of the reliability of different measures as indicators of disease severity (Reeve-Johnson, 1999).

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General Section

TRAINING PIG VETERINARIANS -WHERE DO WE GO FROM HERE? A PERSONAL REFLECTION
J. Carr

Abstract
Training the veterinarian of tomorrow

A successful pig specialist must enjoy the company of pigs and be willing to sacrifice large amounts of personal quality time to understand how to investigate and solve problems of pig production. The veterinary surgeon (VS) is required to understand not only the traditional disease angle; but, more important, the pig's viewpoint; building and stockperson's requirements and failings, which probably lead to the problem in the first place. As pig treatments increasingly rely on applied animal science, veterinarians must be aware that they alone are not required to treat the problem and that they have no monopoly on health maintenance. If the veterinary profession fails to grasp health maintenance and rely solely on medicine based therapy, the farming community will move away from the veterinarian completely. The increasing globalisation of the pig industry will also lead to new systems of problem solving, through the Internet and video conferencing, for example, where distance is not an issue.

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HAEMOPHILUS PARASUIS: A SYNOPSIS
S.H. Done

Abstract
The overall importance of H. parasuis is not well established; but it is believed to be an increasing contributor to polyserositis, pneumonia and pleurisy, as well as being the causative organism of Glässer's disease. Its presence is often suspected but so rarely proven. It is often the cause of clinical disease when it first occurs on the farm and then, over the next few months, as the level of seropositivity rises so the number of clinical cases falls. For every 10% of lung involved in bacterial pneumonia, the average daily gain is lowered by about 3.3%. The % increase in the FCR is roughly equivalent to the % decrease in the growth rate. The range of effects expected for bacterial pneumonia includes a 2-25% decrease in ADG and an increase in FCR of 3-29%. What is really known about H. parasuis infections in the pig? The truthful answer is very little. Few workers concentrate on this organism and, as far as the author is aware, within the UK, there are no research projects on the organism and its diseases. After M. hyopneumoniae has been ruled out, H. parasuis is usually blamed. In other words, its diagnosis often depends on clinical picture, gross lesions and intuition. It can be a serious problem, with a mortality rate reaching up to 10%. Radle (1996) described an outbreak in which the mortality rates were 6.3% in the breeding herd, 18.1% in the growing/finishers and 13.2% in the farrowing and nursery animals. The morbidity reached over 100% for everything over 3 weeks.

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CONTROLLING GLÄSSER'S DISEASE, THE U.S. EXPERIENCE
J.F. Quinlan

Abstract
Background
In the past ten to twelve years the pork industry in the United States has changed dramatically. The US has witnessed a major consolidation of pig ownership, integration of all production phases and movement to All-In/All-Out (AIAO) pig rearing. Today, it is estimated that over 50% of the pigs in the US are raised in two or three stage production systems operating under AIAO management practices. Implementation of these husbandry practices has created high health status herds with benefits of better feed efficiencies, less days to market and in many cases a reduction in the number of disease pathogens. However, raising high health status pigs brings new challenges to pork production. One of the most consistently diagnosed problems, recognised in AIAO production systems, is Glässer's disease caused by infection with Haemophilus parasuis. Infection by this organism leads to colonisation on the serosal surfaces of organs in the pleural and peritoneal cavities. In addition, articular surfaces and meninges may also become infected. Glässer's disease is extremely painful. Affected pigs become lethargic and may show respiratory, abdominal and neurologic signs. While the acute form is most fatal, chronic infection leads to very poor growth performance as lung capacity is restricted, cardiac output compromised, digestive systems interrupted and joint cavities develop extensive arthritic changes.

To better understand the pathogenesis of Glässer's disease, it is important to remember that H. parasuis can typically be isolated from most normal sows. Transmission from the sow's tonsils to newborn pigs may occur from nose to nose contact within the first days of life. H. parasuis organisms have been isolated from the sow's vagina suggesting the possibility of infection during the birth process. It is apparent that many young pigs harbour the organism in a non-clinical state and do not replicate the bacteria until subjected to a stressful event. This delay of incubation and appearance of clinical signs may cause problems in diagnosis and confusion about how best to prevent the disease in pork production units.

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PIG HEALTH IN THE UK 1999; A PERSPECTIVE OF GOOD NEWS AND BAD NEWS
S.H. Done

Abstract
Disease is an important cost associated with efficient production of pigs. Some of these costs are easily recognised in the form of mortality or morbidity (clinical signs); but, in some cases, may be sub-clinical or latent or may cause diversion of nutrients from the production of body growth (muscle * lean meat) to the maintenance of a high level of cell-mediated or humoral immunity.

Approximately 70% of disease costs can be related to alimentary and respiratory diseases. This includes morbidity, mortality, costs of culling and disposal, carcase losses at the abattoir and failure of growth (increase in feed consumption, reduced daily gain and increases days to slaughter). In addition, there are often associated veterinary costs, particularly treatment and vaccination and possibly long term hygiene measures or even depopulation and re-stocking. It is also true that herds affected with serious continual digestive and respiratory disorders will have to use extra labour to maintain the health and welfare of the affected pigs.

The modern day pig, lean, fast-growing, with an ability to grow at twice the rate of the pig of the 1960s, may not be quite as robust in terms of susceptibility to respiratory and alimentary agents, i.e. the "knife edge" is sharper, so more care is needed in building design and management to protect it. Absolutely essential are all in/all out buildings which are well ventilated and easily cleaned, and also good quarantine and isolation facilities, as the pig is the only carrier for a large number of pig pathogens. Most diseases increase as the population of animals rises so farm size, building size, group size and pen size in one airspace or feeding/lying space are quite important. In other words, to reduce the spread of respiratory and alimentary disease, it is often necessary to reduce the stocking density. Under these circumstances many pathogens can survive, be transmitted, infect and colonise, maintain disease and provide a continuous challenge to other pigs. Most diseases are dose dependent and are carried in the nose and transmitted via the air, in the case of respiratory disease, and in the faeces since all alimentary diseases are oral infections from faeces. Therefore to control respiratory disease, the bacterial load in the air must be reduced and in the case of alimentary disease, pens should be designed and managed to reduce oro-faecal contamination. Multi-site production may simply work by giving a pig 2 or 3 periods in clean disinfected buildings with no build-up of disease so it can recover before the next pathogenic challenge, which will also be kept low by the separation from the infectious material.

The acquisition of the pathogenic burden is the key to survival. It occurs at birth, but is hopefully counteracted by effective maternal antibody transfer to colostrum with effective piglet uptake. If it is not, these infected piglets will then rapidly act as a culture medium for their "fellows" in the cohort in the nursery. They will by then be losing their natural immunity (5-8 weeks) prior to the active immunisation process becoming really effective (8-12 weeks).

The very good news The United Kingdom has been able to operate a national isolation policy until joining the European Union (EU). This has meant long-term freedom from several of the most important pig pathogens. This has been augmented in the EU by rigid control of animal movements from infected areas; although transit of pigs from infected countries to slaughter in other countries, whilst transitting a third country may be a worry. The relative risk of shedding pathogens from latently infected animals in transit is probably unknown and hopefully nobody in the EU will find out.

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Clinical Practice

OVERVIEW FROM VLA PIG GROUP
A.M. Barlow

Abstract
This is a brief report of some significant disease conditions investigated by the VLA during the previous year. The review is divided into a number of sections:- Annual submissions to VLA VI Centres; Respiratory disease; Enteric disease; Reproductive disease; CNS/Systemic disease.

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SWOLLEN TESTICLES (ORCHITIS) IN BOARS: AN INVESTIGATION INTO THE PRESENCE OF ACID FAST ORGANISMS
D. Welchman, N. Giles, D. Gavier-Widen, S.H. Done, F. Baird, C.E. Glossop, P. Griffiths, J. Plater, A. MacMillan, S. Spencer, S. Brew, A. Pospichil

Abstract
Degenerative changes were seen in the testicles in five of nine boars and periorchitis in a further animal sufficient to cause sub-fertility or infertility. Acid fast organisms were seen in smears stained by modified Ziehl-Neilsen of the testes or epididymes of eight boars.
Chlamydia psittaci was demonstrated by polymerase chain reaction (PCR) in bloods and in one testes sample. It has not been possible to detect C.pecorum or C.trachomatis or C.trachomatis like organisms or to determine whether the chlamydiae are of avian or mammalian origin. Other acid fast organisms were ruled out and it therefore seems likely that the condition of orchitis/herd infertility was associated with C.psittaci, although it was not definitely proven.

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SALINOMYCIN POISONING IN FATTENING PIGS
J. Morris

Abstract
This case details accidental salinomycin poisoning in fattening pigs (~50kg LW), the clinical signs, post-mortem investigations and feed analysis.

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CYSTITIS AND ENDROMETRITIS IN A 1,000 SOW UNIT
P. Spillane

Abstract
The conception rate in a 1,000 sow unit, calculated as the percentage of sows served that were diagnosed in pig by ultrasound scanning 35-49 days post service, reduced from an average of 88% from January to December 1996 to 79% from January to March 1997.
The conception rate reduced further to an average of 75% from April to September 1997. Clinical investigations, examination of computerised breeding herd records, urogenital organ examinations and laboratory investigations were carried out during the course of an investigation into the problem of poor herd fertility.
A diagnosis of endometritis and cystitis was reached, with sows of fourth parity and older mainly affected. E. coli was the most commonly isolated organism during the course of bacteriological investigations, Streptococci and Staphylococci were also indentified. An initial control programme of in-feed Amoxycillin medication of the sow herd for 14 days and management changes failed to increase conception rate. Subsequently an ammonium chloride (urine acidifier) based control programme was introduced in August 1997 and coincided with a significant increase in conception rate to 87% from October to December 1997 and to 90% from January to March 1998.

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DIARY OF A T.G.E. OUTBREAK IN EAST YORKSHIRE FEBRUARY 1999
P.R. Pemberton

Abstract
This paper gives a summary of the clinical features and control measures of the most recent TGE outbreak, again a possible "one-off," on a unit of 320 sows (farrow to finish) in East Yorkshire, which occurred in February 1999.

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