THE CHARACTERISTICS AND ATTEMPTED CONTROL OF POST-WEANING MULTISYSTEMIC WASTING SYNDROME (PMWS) AND PORCINE DERMATITIS AND NEPHROPATHY SYNDROME (PDNS) IN EUROPEAN PIG HERDS - A REVIEW p.13-
by S.A. Chadd
Abstract
Post-weaning Multisystemic Wasting Syndrome (PMWS) and Porcine Dermatitis and Nephropathy Syndrome (PDNS) are recognised as two diseases of current major international importance, with recorded outbreaks reaching epidemic proportions in post-weaned pig herds in recent times. The aetiology of PMWS and PDNS remains the focus of much research enquiry and Porcine Circovirus 2 (PCV-2) has been identified as the most likely causative pathogenic agent. It is thought probable that the virus is ubiquitous throughout the world. However, despite its occurrence in the herd, a substantial number of herds do not exhibit any clinical evidence of the disease. The mechanism of how vertical and/or lateral viral transmission occurs is not fully understood, although birds are considered a possible vector for the latter.

It is hypothesised by several researchers that other factors are required to induce clinical expression of disease such as additional viral burden (e.g. PRRS), other infectious agents (bacterial overload), immune modulations (stimulation) and associated environmental factors. Differential diagnosis of PMWS and PDNS on-farm is assisted by a fairly precise age distribution associated with the conditions. Porcine Dermatitis and Nephropathy Syndrome outbreaks, observed in older pigs (11-14 weeks) tend to follow PMWS (6-8 weeks) rather than precede them. In the absence of an effective vaccine, control measures are based on generic management changes targeted at reducing disease challenge and potential predisposing factors. The prospects for 'serum therapy' are considered.

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GLOBAL PATTERNS OF PORCINE PROLIFERATIVE ENTEROPATHY p.26-
by S. McOrist, D.E. Barcellos and R.J. Wilson
Abstract
Intensification has seen a worldwide increase in the incidence and severity of Lawsonia intracellularis infections. However, this may have been a simple switch from a chronic to a more acute form, possibly associated with a later onset of infection. The major increase in the 1970s was probably as a result of the increase in the acute haemorrhagic form.

The disease is endemic, but not always visible. It may be more common in the USA and Northern Europe. White breed hybrid stock develop proliferative enteropathy more readily than Duroc-cross pigs. There are two basic patterns of infections. One is characterized by early infection. The other is when there is delayed infection and seen in farms with separation of pigs at weaning and all-in/all-out production. In sows, the infection may be sub-clinical as a "carrier" state. Age separation, particularly at weaning, and the status of the breeding pigs are the major factors identified in pathogenesis.

Lawsonia now has its entire genome studied (Gebhart et al, 2003) and it is seen as a genetically and phenotypically monotypic organism with few, if any, sub-groups yet found.

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VACCINATION RAMIFICATION? AN OBJECTIVE LOOK AT HOW VACCINATION MIGHT AFFECT POST-WEANING MULTISYSTEMIC WASTING SYNDROME (PMWS) AND PORCINE DERMATITIS AND NEPHROPATHY SYNDROME (PDNS) p.36-
by J.D. Mackinnon
Abstract
It has been proposed that immune stimulation plays a pivotal role in the development of clinical post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). More specifically, some researchers have suggested that the vaccination of piglets might act as the major event in this respect. However, in a physiological and clinical sense, it is difficult to single out vaccination as the one important factor because of the gamut of immune modulating agents encountered by piglets post-weaning at a time when their immune system is undergoing rapid expansion. When taken together, limited experiments using both positive and negative intervention in attempts to generate clinical PMWS have given equivocal results. There are distinct differences in the responses to immune stimulation of gnotobiotic pigs and conventional pigs infected with porcine circovirus Type 2 (PCV-2), the agent thought to be responsible for PMWS and PDNS. It has not been possible to reproduce the clinical entity consistently in conventional animals.

Field experience does not suggest temporal or epidemiological relationships between the use of vaccines in piglets and the development of PMWS or PDNS. The emergence of PMWS has taken from between one and nine years in countries where piglet vaccination is practised. At farm level, clinical PMWS can precede the introduction of vaccination, it can occur on farms that have never employed vaccination of piglets and it does not (or has not yet) emerged on farms that do use vaccination. Some of the highest mortality rates due to PMWS have in fact been experienced on farms that do not vaccinate, suggesting that there are many other factors to consider in relation to the emergence of clinical PMWS. Controlled studies in the field so far indicate that there are no differences in mortality rates between vaccinated and non-vaccinated piglets due to PMWS in PMWS-positive herds and clinical experience suggests that the control of endemic diseases by vaccination can mitigate the effects of concomitant PMWS.

Retrospective investigations have demonstrated that PCV-2 has been present for almost 30 years or more in commercial pig populations, so the question arises of whether there have been changes in PCV-2 virulence or changes in the pig population that have led to the emergence of clinical disease, or both. There is no evidence for significant changes to the virus. Convergence and globalisation of pig breeding may have facilitated genetic susceptibility, either as the removal of immune protection or as an enabling of the virus, or the true cause of PMWS has yet to be identified.

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BIOEQUIVALENCE OF SIX GENERIC PREPARATIONS OF ENROFLOXACIN IN PIGS p.64-
by L.H. Sumano, C.L. Ocampo and O.L. Gutierrez
Abstract
Given the importance of enrofloxacin in the treatment of bacterial diseases in pigs and the abundance of generic preparations available on the market, a bioequivalence study of 6 generic preparations of this drug and Baytril® was carried out. Forty-two non-medicated pigs were placed in groups of six and each preparation was injected IM at a 5 mg/kg bolus dose. Blood samples were obtained at various times and serum was recovered and analysed by a quantitative/qualitative microbiological agar diffusion analysis. Serum concentration/activity vs. time profiles and pharmacokinetic data derived from these curves, revealed lack of bioequivalence of all tested preparations. The reference enrofloxacin showed the highest AUC and Cpmax values (P< 0.05). The highest Cpmax average value of tested generics was only 46% of the reference enrofloxacin, 15% being the lowest value obtained. However, generic preparations were statistically indistinguishable in most instances. These results may partly explain different clinical outcomes and stress the need to carry out bioequivalence trials to register a new generic preparation.

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EFFECT OF CHILL TYPE ON THE QUALITY OF PIG MEAT FROM FARMS SUSPECTED OF PRODUCING HIGH OR LOW INCIDENCES OF PSE (PALE, SOFT, EXUDATIVE) p.74-
by D.J. O'Neill, D.J. Troy, P.G. Lawlor, D.J. Duckley and J.P. Kerry
Abstract
The conditions of PSE (pale, soft, exudative) and DFD (dark, firm, dry) in pigmeat are economically undesirable. The objective of this study was to determine if differences in chilling procedure influenced the quality (colour, pH and appearance) of pigmeat from four farms, two of which had a higher than average incidence of PSE and two having a low incidence. A total of 30 pigs were selected per farm each week for a total of 5 weeks (n=600) and the groups were split evenly between new (more rapid) and old chill rooms each day. Carcass pH taken at the 3rd/4th rib was measured 45 minutes, 90 minutes, and 24 hours after slaughter. Using a Minolta colorimeter (Hunter L, a, b scale), colour of the Mm. Longissimus dorsi muscle was measured 24 hr after slaughter, while the colour was also visually scored on a scale of 1-6 using Japanese colour comparison blocks. Farms of origin had a significant effect on both the pH at 24 hours (P< 0.001) and colour (Hunter "L," P< 0.001; Hunter "a," P< 0.001). Chill type had no significant effect on incidences or causes of PSE detected. It was concluded that changing chill conditions could not mask the difference in the incidence of PSE due to on-farm factors.

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EFFECT OF GARLIC (ALLIUM SAVITUM ), HORSERADISH (AROMATICA RUSTICANA ) AND ENROFLOXACIN IN THE PREVENTION OF PERIPARTURIENT DISORDERS AND PRE- AND POST-WEANING MORTALITY IN SWINE p.83-
by J. Sika and G. Bilkei
Abstract
This study was designed to examine the effect of addition of garlic, horseradish or enrofloxacin in the prevention of periparturient disorders in sows and pre- and post-weaning mortality in piglets. The trial was performed in Hungary from September to December 1999 in a large herd of 1900 sows.

Sows of average body condition and parity were assigned pre-partum to one of four experimental groups and received in their diet either 1000 ppm dry garlic powder (group one), 1000 ppm dry horseradish powder (group two), 50 ppm enrofloxacin (group three) or no supplement (group four, control). The occurrences of periparturient disease complex (PDC), pre- (PM) and post-weaning mortality (PWM) were evaluated.

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POST-WEANING PROBLEMS IN OUTDOOR PIG PRODUCTION CAUSED BY ESCHERICHIA COLI AND CLOSTRIDIUM PERFRINGENS TYPE A p.-
by B. Dora and G. Bilkei
Abstract
Escherichia (E.) coli caused post-weaning problems and Clostridium perfringens Type A (CpA) caused enteric diseases and now represent a newly emerging danger for outdoor raised grower pigs in Croatia. This paper summarises the major clinical and gross pathological signs of the diseases. In order to reduce post-weaning losses, prophylactic medication against both CpA and E. coli has been successfully implemented. Prophylaxis for one of the causative agents was less successful than for both of them.

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POST-WEANING PROBLEMS IN OUTDOOR PIG PRODUCTION CAUSED BY ESCHERICHIA COLI AND CLOSTRIDIUM PERFRINGENS TYPE A p.92-
by B. Dora and G. Bilkei

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POST-WEANING MULTISYSTEMIC WASTING SYNDROME (PMWS) AND PORCINE CIRCOVIRUS TYPE 2 INFECTION IN SPAIN p.98-
by J. Segales, M. Calsamiglia and M. Domingo
Abstract
In Spain, post-weaning multisystemic wasting syndrome (PMWS) was firstly recognised in 1997. Since then, the disease has been diagnosed in pigs from most of the Spanish provinces and it is nowadays considered one of the major concerns for veterinarians, farmers and scientists. More than 2600 pigs, from about 500 different farms, were diagnosed as PMWS by the Pathological Diagnostic Service at the Veterinary School of Barcelona between 1997 and 2002. Retrospective investigations have shown the existence of the disease in Spain as early as 1986, although its incidence was low compared with the last 6 years. Epidemiological data indicate that PCV2 infection is highly widespread in Spain, and no obvious differences in serological and polymerase chain reaction (PCR) profiles have been detected between PMWS and non-PMWS affected farms. Since no specific treatment exists for PMWS, zootechnical measures to reduce the so-called "infection pressure" of PCV2 and any other pathogen have been applied in Spain with variable success. A moderate to high proportion of porcine dermatitis and nephropathy syndrome (PDNS) and porcine respiratory disease complex (PRDC) affected pigs are also infected with PCV2. Although PCV2 has been related with reproductive failure and congenital tremors type AII, no evidence for this association has been observed in Spain.

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ON-FARM POST-WEANING MULTISYSTEMIC WASTING SYNDROME (PMWS)/PORCINE DERMATITIS AND NEPHROPATHY SYNDROME (PDNS) STUDY: AIMS AND OBJECTIVES p.108-
by D.P. King, S.S. Grierson, M. Banks, A.C.J. Gresham, M. Bailey, K. Haverson, C. Sargent, G.J. Wellenburg, D. Tucker, M. Donadeu and M. Mellencamp
Abstract
Porcine circovirus-2 (PCV-2) has been implicated as the causative agent of Post-weaning multisystemic wasting syndrome (PMWS) and has been closely associated with Porcine dermatitis and nephropathy syndrome (PDNS). However, it is apparent from a number of experimental studies, that when inoculated alone, PCV-2 does not consistently reproduce disease. This observation has driven speculation regarding the likely contribution of additional factors that may have impacted upon the increased expression of these syndromes in UK pigs in the past three years. In order to address this question, the immunological and transcriptional events occurring in individual piglets prior to the clinical presentation of PMWS and PDNS will be monitored and compared with unaffected litter-mates. This will allow key biochemical pathways that modulate the expression of these syndromes to be identified. This knowledge should facilitate the development and targeting of therapeutics, vaccines and diagnostic tests for these important emerging pig diseases.

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THE PATHOLOGICAL FINDINGS IN PIGS EXPOSED TO AERIAL POLLUTANTS p.119-
by S.H. Done, A.C.J. Gresham, S. Williamson, B. Hunt, D.J. Chennells, R.P. White, T.G.M. Demmers, N. Teer, C.M. Wathes, L. Taylor, V. Bland, P. Jones and D. Armstrong
Abstract
A controlled experiment to discover the effects of aerial pollutants on pigs is described. The methodology is set out and the results, physical, bacterial and pathological, are well tabulated. Although nothing positive is deduced biologically, some degree of statistical significance was noted.

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INVESTIGATION OF THE TRANSMISSION AND SPREAD OF PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME (PRRS) p.131-
by D.J. Chennells
Abstract
Otake et al (2002) conducted an experiment attempting to transmit Porcine Reproductive and Respiratory Syndrome (PRRS) from pigs inside a building to those outside when placed adjacent to a fan exit point; but did not succeed.

This paper gives the results of some investigations carried out on finisher pigs which were part of another trial (the MLC Finishing Systems Project).

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TAIL BITING AND TAIL DOCKING IN PIGS p.136-
by S.H. Done, J. Guise and D.J. Chennells
Abstract
A study was carried out to evaluate the effect of tail docking on behaviour following docking, using different methods and to determine the effect of tail docking on the physical structure of the tail. This study was prompted to investigate the very limited study of Simonsen et al (1991) who showed the presence of neuromas in the docked tails.

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TAIL NECROSIS IN PIGS p.155-
by R. Blowey and S.H. Done
Abstract
Necrosis of the skin has been observed in pigs over a long period. Hutura et al (1938) described a necrosis of the tail in 2-4 day-old piglets, which started as a red ring at the base of the tail. This condition could be prevented by painting the tail with iodine and glycerine soon after birth.

Necrosis of the tail was said to be due to vaso-occlusion (Shuman, 1964) possibly caused by erysipelas, salmonellae or streptococcal infection; but tail sloughing is not characteristic of erysipelas in very young pigs (Peterman, 1944) and erysipelas is not very common anyway (Sindrey and Creyke, 1948). Hare et al (1942) described eta-haemolytic streptococcal infections a cause of necrosis of the tail, as part of a generalised syndrome.

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THE PREVALENCE AND CLINICAL DISEASES CAUSED IN PIGS BY DIFFERENT SEROTYPES OF STREPTOCOCCUS SUIS (June 2000 to September 2002) AND HUMAN INFECTION (1981 to October 2002) IN ENGLAND AND WALES p.164-
by A.M. Barlow, B.W. Hunt, P.J. Heath and R.M.M. Smith
Abstract
This paper gives a brief overview of Streptococcus suis, including background history, serotypes and disease, epidemiology, virulence, species affected and zoonosis. Data collected by the Communicable Disease Surveillance Centre (CDSC) from Public Health Laboratory Service (PHLS) returns for England and Wales are detailed. Also presented is information from scanning surveillance carried out by the Veterinary Laboratories Agency (VLA) indicating the clinical diseases caused by different serotypes of Streptococcus suis in England and Wales, as well as their prevalence.

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STREPTOCOCCUS SUIS - ELIMINATION OF THE CARRIER STATUS? p.177-
by W.D. Strachan, M.A. Maclennan, S.L. Douglas and J.R. Thomson
Abstract
Previous attempts to prevent the transmission of Streptococcus suis to piglets by antibiotic medication of the adult sow have been unsuccessful. The oral administration of tilmicosin to adult breeding animals in order to eliminate the carrier status for Actinobacillus pleuropneumoniae and Mycoplasma hyopneumoniae has previously been described. This paper describes the use of oral tilmicosin preventing the transmission of Streptococcus suis serotype 1/2 from sows to their offspring on two units. In one case, tilmicosin was used in a modified segregated disease control (SDC) programme to eliminate clinical evidence of enzootic pneumonia and streptococcal meningitis from the herd. In a second case, treatment of a group of sows successfully resulted in prevention of clinical disease in their offspring.

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STUDIES ON PUTATIVE VIRULENCE GENES OF PORCINE BRACHYSPIRA SPECIES p.184-
by C.A. Walker, B.P. Murray, J.R. Thomson and K. Sumption
Abstract
This paper reviews the putative virulence factors associated with porcine Brachyspira species including haemolysins, motility factors, iron transport systems, mucus attraction genes, outer-membrane proteins, adhesion factors and oxygen metabolism (NAD oxidase). Thereafter an overview is given of a molecular-based study on putative virulence genes in Brachyspira field isolates, comparing their prevalence in virulent isolates of B. hyodysenteriae with that in mild/non-virulent isolates of this species. Of the six putative virulence genes studied, only the glucose-galactose lipoprotein gene MglB showed a significantly higher prevalence in virulent B. hyodysenteriae as compared with mild/non-virulent isolates. This gene shows potential for further study towards classifying B. hyodysenteriae in terms of virulence potential.

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THE ROLE OF VITAMIN NUTRITION ON SOW AND PIGLET HEALTH p.198-
by C. Antipas and G. Weber
Abstract
The main components of sow health and productivity are weaning to oestrous interval, sow culling rate and number of piglets weaned. They can be improved through genetics, management and nutrition. Within nutrition, vitamins have been demonstrated to be essential for protecting sow and piglet health and for maximising herd productivity. Supplementation of the diet with biotin reduces weaning to oestrus interval and culling rate and improves fertilisation rates. Vitamin E supplementation during early pregnancy improves ovulation rate whereas folic acid enhances embryonic and foetal survival. Vitamin A and/or -carotene enhance embryo quality and thus have beneficial effects on litter size at birth and at weaning. Vitamin limitations (e.g. vitamin A) during foetal growth could compromise health and growth potential of piglets after birth. Colostrum and milk are enriched with vitamin E and other vitamins that are readily transferred to the piglet to support its health and growth. High levels of vitamins E and C in the piglet's blood through milk from the sow can help it to overcome stresses imposed by the weaning process. There is plenty of evidence to prove the multiple benefits of vitamins on sow health, reproductive performance and subsequent piglet health. Thus, vitamin supplementation guidelines should not only aim at avoiding deficiencies; but also ensure optimum vitamin nutrition of both sows and piglets to maximise herd productivity.

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THE ANIMALS (SCIENTIFIC PROCEDURES) ACT 1986 AND THE PERFORMANCE OF PROCEDURES BY VETERINARY SURGEONS p.211-
by A.-M. Farmer
Abstract
The Veterinary Surgeons Act 1966 [VSA] allows qualified and registered veterinary surgeons to undertake procedures on animals. However, there are situations when veterinary surgeons need to be aware of other legislation, which could impinge on what they do. One such piece of legislation is the Animals (Scientific Procedures) Act 1986 [ASPA] which is designed to control all work which has the potential to cause pain, suffering, distress or lasting harm to animals when done for a scientific purpose. On occasions, the line between the VSA and ASPA can be very fine. This paper is designed to help veterinary surgeons identify when procedures fall within or outside ASPA.

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THE VETERINARY PROFESSION AND THE ROYAL COLLEGE OF VETERINARY SURGEONS (RCVS): IS THERE A FUTURE? p.217-
by R.G. Eddy
Abstract
The current concerns of Veterinary Surgeons with regard to Government intervention in the profession, and possible binding legislation arising from it, are outlined by the author. The far-reaching consequences of such political actions on the viability of the profession and the current integrity of the Royal College of Veterinary Surgeons are also touched on. Effects on other professions, similarly targeted, are noted by way of comparison.

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BOAR TAINT - IS IT AN ISSUE FOR BRITISH PORK? p.221-
by D.G.S. Burch
Abstract
A survey of the audience at the Pig Veterinary Society meeting was held to assess what was the importance of 'Boar Taint' on the purchase of fresh pig meat. Patriotic support for British pork was unsurprisingly very high (score10/10); but the importance of boar taint was also ranked very high (score 9/10), especially with regard to meat quality and competition from Denmark. If this issue could be overcome, possibly by the reintroduction of castration, British pig meat could compete more equally with Danish or any other European product in quality and national support and make the market grow.

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NOT ALL THIN PIGS ARE POST-WEANING MULTISYSTEMIC WASTING SYNDROME (PMWS) - A CASE HISTORY p.227-
by D.J. Chennells
Abstract
The author describes a case of oesophageal obstruction in an 85 Kg finisher pig. A comparison is made with Barratts Syndrome in human beings.

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'TALES OF THE UNEXPECTED' p.230-
by A. Hughes
Abstract
The author outlines a case history, relating to a group of 700 pigs introduced onto a finishing-unit in N. Yorkshire. A variety of symptoms and unexplained deaths were manifested after a period of seven weeks. Diagnostic tests and autopsies were carried out on a progressive basis and feeding regimes analysed. In all, there was a 17% mortality in the group over 15 weeks. Histopathology and bacterial tests indicated the presence of Porcine Dermatitis Nephropathy Syndrome (PDNS), Post-weaning Multisystemic Wasting Syndrome (PMWS) and Glässer's Disease. Contributory stress factors were possibly involved and remedial measures suggested.

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Sponsor' Papers

THE ROLE OF MATERNALLY DERIVED ANTIBODIES, AGE AND OTHER FACTORS ON VACCINAL RESPONSE (THE PERCENTAGE GAME) p.242-
by D.G.S. Burch
Abstract
The economic importance of Mycoplasma hyopneumoniae infection and its control are examined in depth by the author. The natural immunological reaction of the pig is described, as is the subsequent influence of vaccines in promoting enhanced disease resistance. The effects of such vaccines on disease progress and the various factors affecting their efficacy are also highlighted, together with cogent pointers as to their best use.

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Members' Papers

THE UK PIG MEAT MARKET: STRUCTURE AND TRENDS 2001 p.258-
by D.G.S. Burch
Abstract
The UK pig market has gone through some major contraction over the last few years with pigs slaughtered collapsing from a peak of 16.5 million to 10.2 million in 2002. The strength of the pound against the European currencies and now the Euro, the unilateral introduction of welfare codes, especially related to the banning of stalls and tethers, the banning of meat and bone meal as a feed ingredient following BSE, reduced the UK's competitiveness with the European producers making it more vulnerable to imports of cheaper meat. Disease has also had a major impact. Post-weaning multisystemic wasting syndrome (PMWS) damaged productivity; but this also affected other European countries; although only more recently, Denmark. Swine fever in 2000, and Foot and Mouth disease (FMD) in 2001 also took its toll, not so much directly, as relatively few farms were affected; but indirectly by movement and export restrictions. As much of a pig veterinarian's work is linked to pork production, it is a great concern to see the falling numbers, as well as the major changes that are going on in the UK market. Are they reversible, one asks?

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