POST-WEANING MULTISYSTEMIC WASTING SYNDROME IN FRANCE: WHAT WE HAVE LEARNT FROM FIELD EPIDEMIOLOGY
N. Rose and F. Madec

Abstract
Ten years ago, the first descriptions of a new emerging syndrome were reported in France. This new disease, called Post-Weaning Multisystemic Wasting Syndrome, was devastating in many French farrow-to-finish operations in the early period of the onset of the disease. In the authors' laboratory, a strategy was developed to find emergency solutions in severely affected herds and to learn from those case studies the first rules of the epidemiology of this new syndrome. Those first observations were the basic elements for further investigations combining epidemiological field studies (cross-sectional studies, cohort studies) and experimental trials in the level three biosecurity facilities. The use of this multidisciplinary approach, joining the teams in virology, experimentation and epidemiology, led to the identification of the main farm level and individual level risk factors for the syndrome. Experiments carried out with SPF sows and growing pigs free from PCV1 and PCV2 contributed to a large extent to further validate and understand the biological involvement of the risk factors in the pathogenesis of the syndrome.

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NEW DEVELOPMENTS IN VACCINE TECHNOLOGY
A.R. Peters

Abstract
New developments in vaccine technology are reviewed, including descriptions of sub-unit antigens, DNA vaccines and live attenuated-gene deleted vaccines, together with the concept of differentiating infected from vaccinated animals (DIVA). The importance of recent advances in genomics in relation to host-pathogen interactions is discussed, as well as some new possible vaccine targets, e.g. parasites, reproduction. The processes and implications of technology transfer, product development and regulation in relation to veterinary vaccines are also briefly reviewed.

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IMPROVAC™ (PFIZER ANIMAL HEALTH): AN IMMUNOLOGICAL PRODUCT FOR THE CONTROL OF BOAR TAINT IN MALE PIGS (I)
J.D. Mackinnon and M.C. Pearce

Abstract
I. Boar taint and its control and the mode of action, safety and efficacy of Improvac™

Boar taint is caused primarily by the male steroid androstenone, and skatole - a bacterial metabolite of tryptophan. Potentially, taint is a major limiting factor to the marketing of pig meat derived from carcases of entire male pigs. Androstenone can only be detected by sensitive subjects who generally find the smell highly offensive, whilst skatole can probably be detected by nearly everyone. The occurrence of boar taint shows national, regional and seasonal differences which can be influenced, but not eliminated, by feeding and management practices. The most effective and widely practised method of controlling boar taint currently is the painful and undesirable procedure of surgical castration. However, the new technology of immunocastration, utilising the product Improvac™, offers a real and welfare friendly alternative.

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IMPROVAC™ (PFIZER ANIMAL HEALTH): AN IMMUNOLOGICAL PRODUCT FOR THE CONTROL OF BOAR TAINT IN MALE PIGS (II)
J.D. Mackinnon and M.C. Pearce

Abstract
II. Practical application in pig production and potential production benefits

This review examines the practical application and production benefits of Improvac™ (Pfizer Animal Health) - an anti-GnRF immunological product containing a GnRF peptide conjugate in an aqueous-based adjuvant. Vaccination of entire male pigs against naturally occurring gonadotrophin releasing factor (GnRF) provides a highly effective and welfare friendly alternative to surgical castration for the control of boar taint, with substantial additional benefits to pig producers. Because vaccination can be timed to occur close to slaughter, the use of this new technology enables the producer to capitalise on the natural growth and carcase characteristics of entire male pigs. Compared with surgically castrated males, pigs managed with Improvac™ utilise feed more efficiently and produce a leaner carcase. The suppression of characteristic peripubertal male behaviour improves terminal growth performance, enhances welfare, and reduces the risk of injury and compromised carcase quality.

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PHARMACOKINETICS OF ANTIMICROBIALS AT DIFFERENT LEVELS OF THE INTESTINAL TRACT AND THEIR RELATIONSHIP TO ESCHERICHIA COLI RESISTANCE PATTERNS IN THE PIG
D.G.S. Burch

Abstract
The first part of the paper looked at the pharmacokinetics of a liquid non-absorbable compound as it passed along the small intestines of adult pigs. Only 38.8% of the dose was recovered in the upper small intestine, 71.5% in the middle third, but 100% in the lower third or ileum over a 12 hour period. The first time point was at two hours after dosing, when the stomach had passed 51% of the dose and 71.5% by 4 hours. It was thought that inadequate sampling points prior to two hours meant that a substantial portion of the dose had been missed in the upper small intestine and had already passed down to the lower small intestine. A calculation was made, based on the area under the curve (AUC) from the stomach and added to the upper small intestine and this increased the recovered dose to 81.6%. Using the routine in-feed usage pharmacokinetic data of AUC projected over 24 hours and available gut or faecal concentration data or estimations, the mid-small intestine concentrations were compared with the epidemiological cut-off values (ECOV) for various antimicrobials against porcine E. coli from Danish slaughterhouse monitoring and diagnostic isolates. Similarly, the clinical breakpoints (CBP) (one dilution lower than the NCCLS resistance breakpoints) were also examined in this AUC/MIC analysis. Most of the bacteriostatic antimicrobials were around or exceeded the AUC/MIC ECOV ratio of 24, which denotes inhibition, and all the bactericidal compounds exceeded 100. When the AUC/MIC CBP ratios were examined, the majority of bactericidal antimicrobials exceeded 100, except enrofloxacin, and for the bacteriostatic compounds, spectinomycin was well below. Trimethoprim and sulphonamides alone were also consistently low, but when used in a combination, their synergistic bactericidal activity exceeded the 100 threshold. Fundamental pharmacokinetic /pharmacodynamic analysis of antimicrobials in gut contents appears to be applicable to E. coli infections in the small intestine.

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CLINICAL COMPARISON OF TISSUE TOLERANCE OF MELOXICAM 20mg INJECTABLE AND FLUNIXIN INJECTABLE IN PIGS
T. Magyan and R. Glavits

Abstract
A total of 32 pigs, equally divided into two treatment groups, were used in this blind, positively controlled, randomised clinical study. Group 1 pigs received meloxicam 20mg injectable solution and Group 2 pigs received flunixin 50mg/ml injectable solution as single intramuscular injections.

Pigs were sacrificed on days 2, 5 and 15 post-injection and gross and histopathological examinations of the injection sites of all animals were performed. Gross examination of injection sites revealed measurable lesions in seven out of sixteen meloxicam-treated pigs and in fifteen out of sixteen flunixin-treated pigs. Histopathological examinations confirmed that lesions were fewer and less severe in pigs treated with meloxicam compared with those treated with flunixin.

The results of this study show that meloxicam administered intra-muscularly will give significantly less severe macroscopic and histopathological lesions than flunixin meglumine solution.

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HIGH LIVER ZINC CONCENTRATIONS ASSOCIATED WITH THE USE OF ORAL ZINC OXIDE ADMINISTRATION IN PIGS. IMPLICATIONS ARISING FROM A ROUTINE POST-MORTEM EXAMINATION
J.H. Payne, C.J. Livesey and G.J. Jackson

Abstract
Zinc is widely distributed throughout the body and plays an essential role in many body processes. It is believed that zinc inhibits the growth of pathogenic bacteria that might otherwise adversely affect the newly weaned pig. For this reason, in Great Britain porcine weaner diets are frequently medicated with zinc oxide. Standard inclusions rate are 3.1kg per tonne contributing 3100ppm ZnO, equivalent to 2500ppm zinc.

The authors report post-mortem findings of two eight-week-old pigs, together with two small scale studies, prompted by the unusual findings on the index farm. On the index farm, there was a history of recent increased mortality, anaemia and scour in a herd known to have post-weaning multi-systemic wasting syndrome (PMWS). Zinc oxide supplementation was given from 3 to 9 weeks of age. Since anaemia and scours can both be associated with zinc toxicity, this aspect was further investigated. Liver zinc concentrations of 425 and 823 ppm were measured (laboratory reference range 24 to 69 ppm).

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IS THERE A ROLE FOR DIETARY FIBRE IN THE CONTROL OF POST-WEANING COLIBACILLOSIS IN THE NEWLY WEANED PIG?
I.J. Wellock, J.G.M. Houdijk, I.Skoufos, P.D. Fortomaris and I. Kyriazakis

Abstract
This paper summarises the potential role of dietary fibre and, in particular, non-starch polysaccharides (NSP), in the control of post-weaning colibacillosis (PWC), including the results from a series of experiments carried out at the Scottish Agricultural College (SAC).

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POST-WEANING E.COLI DIARRHOEA
R.M. Friendship and M.R. Amezcua

Abstract
Post-weaning diarrhoea in pigs is a complex disease with multiple contributory factors. In the late 1990s, an outbreak of disease occurred in Ontario characterized by sudden death and severe watery diarrhoea in newly weaned pigs. An investigation was undertaken to determine whether the disease was caused by a change in management and/or nutrition or whether<i> E. coli</i> had become more virulent. In addition, a series of trials, both clinical field studies and controlled challenge studies, were undertaken to determine the efficacy of various control measures. In a case-control study of 50 farms, it was determined that management factors did not appear to be associated with an increased risk of disease. The most common <i>E. coli</i> isolated from cases of diarrhoea O149 F4 (STa, STb, LT) was shown to be different from the predominant strains isolated from cases a decade earlier, suggesting that the disease was in part due to a more virulent pathogen. Novel approaches to control of the disease including vaccination, egg-yolk antibody products, probiotics, essential oils and bacteriophages were investigated. Certain of these intervention strategies showed promise in the laboratory and in controlled studies, but their effectiveness under the field conditions remains in doubt.

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PRESSURE-RELATED ABDOMINAL CHANGES IN PIGS WITH 'WHEY BLOAT' - A CASE REPORT
J.R. Thomson, W.G. Miller, N.J. Woolfenden and D. Thomson

Abstract
Investigations were undertaken into sudden deaths on two whey-feeding units, with the aim of furthering understanding of the pathogenesis of 'whey bloat'. Post-mortem examination of 28 cases showed typical changes of 'haemorrhagic bowel syndrome,' but intestinal torsion around the root of the mesentery was present in only two cases. No evidence of enteropathogenic bacteria or intestinal clostridial toxins were demonstrated in any animals tested. Intra-gastric pressure measurements were recorded shortly after death to determine approximate intra-abdominal pressure values. The mean intra-gastric pressure of 6 pigs affected with 'whey bloat' was 40.83 ± 4.4 mmHg, as compared with 3.5 ± 1.5 mmHg in pigs from other units that had died from unrelated causes. Biomedical research in pigs has shown that intra-abdominal pressure of 30 mmHg resulted in life-threatening multi-organ dysfunction during simulated human 'abdominal compartment syndrome' experiments. These findings suggest that the intestinal changes associated with 'whey bloat' can be the direct consequence of high intra-abdominal pressure which is fermentation-related, often without intestinal torsion. Prevention of 'whey bloat' involves restriction of the whey intake to no more than 20% of the total ration on a dry matter basis, feeding the whey as part of a complete ration via a liquid feeding system and taking measures to reduce intestinal fermentation.

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VETERINARY CARE OF THE ORGANIC PIG HERD
P. Bown

Abstract
The set-up and organisation of an organic pig farm is reviewed. The paper emphasises the need for the private veterinarian to become closely involved in the business so that identified pitfalls can be avoided. It is recommended that an organic pig herd should be created from modern genetic stock and enjoy freedom from the major pig pathogens. In such circumstances an organic pig herd can be productive and profitable.

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THE USE OF PLATE COUNT AGAR AND PETRIFILM™FOR THE ENUMERATION OF VIABLE ORGANISMS
G. Woodhead, A. Pritchett and M.A. Jones

Abstract
Two techniques for enumerating viable aerobic organisms in 41 samples of extended boar semen containing antibiotics were compared. High total viable counts were found in many samples by both techniques. There was no correlation between the simpler Petrifilm™ method and the spiral and spread plating techniques on plate count agar. In some cases, the Petrifilm™ grossly under-estimated the number of microbes present due to the effects of inhibitory substances produced by some bacteria.

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REGISTERING NEW PRODUCTS FOR PIGS - (WHY ARE THERE SO FEW?)
P. Watson

Abstract
This paper deals with the economical problems relating to the development of new drugs for the livestock industry. It details the costs of such production and equates it with the associated profit of the manufacturers. It also touches on the actual market for those new products, including the willingness, or otherwise, of farmers to pay the necessary costs, with the consequent risks faced by the investors. The author is sanguine about the future of such pharmaceutical drugs and predicts a possible change in emphasis in favour of vaccines and biologicals generally.

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AIVLOSIN®- THE NEW ILEITIS THERAPY FOR PIGS - A PRACTITIONER'S VIEW
R.M. Kelly

Abstract
The clinical and economic effects of Porcine Proliferative Enteropathy (PPE) are described by the author. PPE, or Ileitis, is common on modern pig units and more so, perhaps, on higher health premises. This could be due to the absence of competitive gut pathogens. Controlled treatment trials were carried out on selected infected groups, using either Tylosin or Aivlosin®. Results indicated that those groups treated with Aivlosin® showed increased body weight at slaughter.

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