Biomedical subjects
Publications and source records attributed to F Madec.
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In the pregnant tethered sow, water intake and motor activity were found to be related to urinary problems and productivity. Therefore, further studies were undertaken on these points. The 258 pregnant sows from eight breeding finishing herds were submitted to water intake control and the investigation of motor activity was performed on 125 pregnant sows from 6 herds. Despite the same process of water supply, the intake varied a lot from sow to sow (mean: 17 litres/day/pregnant sow, (sigma = 6.9 l). The major part of water was drunk during feeding time. The following factors were found associated with water intake: body condition, lameness, parity, stage of pregnancy. The relations between water intake and urine composition were assessed. A low water intake was close related to high urine gravity and to abnormalities (crystals, proteinuria, bacteriuria). The pregnant tethered sows spent an average time of 250 min in the standing position. A diurnal rhythm was clearly observed and it was synchronized by feeding time. The following factors were found to be related to the standing time: parity, body condition, lameness. The frequency of standing up per 24 hours was not related to the total standing time. Under farm husbandry, standing time is rather inconstant in individual sows on subsequent days. Since photo cell apparatus cannot be used as a routine in veterinary practice, we have looked for a more simple method: the position of the sows one hour after feeding time. This index gave an accurate view of the total standing time and represented a practical parameter for epidemiological purposes. The relevance of measuring water intake and motor activity in veterinary practice is discussed.
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A study is carried on in a group of 16 commercial breeding-finishing units in Brittany (France). The aim of this study is to try to reveal the persistence of activity of the Influenza Virus within these intensive units after an acute epizootic. In each farm two batches of pigs are selected, individually identified and followed from suckling period to slaughter. Serological controls are conducted every month on the same pigs. Both Influenza and Aujeszky's disease antibodies are apprehended. Furthermore nasal swabs and lungs are submitted to analysis for virus isolation purposes and data are collected from each herd for epidemiological studies. Influenza passive H.I. Antibodies rapidly decrease in the piglets. Later a seroconversion is observed in 10% of the investigated piglets. These pigs belong to 4 herds. The conversion happens usually after 3 months of age. All attempts to isolate the virus failed. Special herd conditions may be associated with a persistence of the viral activity inside the units between epizootics: bad demography (unbalance in the breeding stock), inadequate hygiene policy in the fattening house (with permanent arrivals of pigs coming from subsequent batches of sows), a high prevalence of respiratory and specially pulmonary enzootic diseases. A seroconversion against Aujeszky's disease is pointed out in 3 out of the 4 herds concerned with Influenza virus activity suggesting that closely the same conditions may be related both to influenza and Aujeszky's disease virus activity.
A seroepidemiological survey using the radial haemolysis test has been performed on a representative sampling of the pig herds in Brittany. Since 1978, Influenza A H3N2 strains spread in that reservoir giving subclinical infections. We detected antibodies directed against the Influenza prototypes isolated during the human outbreaks from 1973 to 1977. Only one H3N2 virus was isolated in 1980: its antigenic structure was in agreement with the previous serological data. In 1984 outbreaks of swine Influenza A H3N2 occurred. The isolated viruses carried an hemagglutinin antigenically identical to the one of the 1980's strain but the neuraminidase looked clearly different. When studying the specific immune response of the young animals to the influenza infection, it appeared that the hemagglutinin of the 1984's viruses antigenically varied from the 1980's ones in about 2/3 of all the animals. With monoclonal antibodies anti N3 and N2 of the human prototypes we confirmed the data obtained in using the post infection ferret antisera. Monoclonal antibodies directed against the swine H3N2 1984 viruses are in preparation. We have no precise information so far on the mechanism of the antigenic variations.
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Having described certain aspects of confinement in modern pig reproductive farms, the writers give a list of the main diseases in sows. Urinary problems are the most frequent. They can be linked to certain aspects of confinement, as can also be locomotory or respiratory troubles. This is not sufficient, however, to condemn modern conditions in reproductive pig farms but appropriate adjustments can be made to associate good health in the animals and satisfactory performances. The advantage of studies on the behaviour of sows is stressed, notably within the framework of ecopathological studies.
Since 1976, seroepidemiological surveys using radial haemolysis and isolation trials from samples collected from pigs at the abattoir showed that Brittany was an important reservoir of swine subclinical infections due to the human Influenza A viruses H3N2. Influenza A H1Sw N1Sw subclinical infections sporadically occurred from 1979 to 1981. In January 1982 an epizootic started in Finistère which spread from west to east. The H1Sw and N1Sw antigens of 28 stains isolated from 1979 to 1982 were studied with ferret and rabbit anti sera and appeared to be variants of the previous strains (1976-1967-1961-1930). A reinforced serological survey in pigs demonstrated that both Influenza A viruses H1Sw N1Sw and H3N2 simultaneously spread in herds. There is no actual prove of recent human infections by A H1Sw N1Sw virus.
Pathologists are always tempted to account for the occurrence of diseases by the presence or absence of some specific microbiological agent. It is the case when a major infectious agent is in contact with a receptive animal. When the Transmissible Gastro-enteritis virus is introduced into a susceptible herd, the results of the infection are calamitious. Nevertheless, the relationship between the infection and the disease is rarely simple. It is necessary to distinguish two kinds of diseases: --the monofactorial diseases (T.G.E....) --the multifactorial diseases (Colibacillosis especially after the weaning...). For these multifactorial diseases the clinical signs and the lesions are induced by an infectious agent which can be considered as a final "effector" whose multiplication depends on factors in the farm which disturb physiological or immunological mechanisms of regulation (humoral immunity, clearance, intestinal motility...). The herd system can be defined by 6 variables which could be considered as limiting factors responsible for the onset of digestive disorders: food, building, management, animal with specific and non-specific resistance, microbism and the farmer who plays a main role in the control of these variables. The disease has to be considered not only as the result of the multiplication of the microbe which is often the last actor of a morbid process but also as the disharmony of the variables defining the structure of the herd.
An ecopathological study was conducted in Brittany (France) in 89 conventional herds in order to identify the main circumstances that permit the onset of weaning disorders. By comparing the different practices in affected and non-affected herds using multidimensional data analysis methods, a combination of 10 variables was found. These variables are considered as predisposing factors and called "risk factors". They are connected and have a cumulative effect. Preparation to weaning (piglets' weights at weaning, feeding level ingested during suckling period) and environmental conditions of reception of the weaned piglet such as housing requirements are needed.
Although poultry is recognized as the major source of food-poisoning caused by Salmonella, pork also contributes to human infections. This study was therefore undertaken in order to develop a reliable serological method for the evaluation of the Salmonella status of piglets. A complete ELISA was performed using lipopolysaccharides of Salmonella Typhimurium, Anatum, Hadar and Infantis because these serovars were representative of the serogroups isolated from 30 contaminated fattening farms. S. Enteritidis was also added because of its importance in human infection and to include the O:9 antigen. This method potentially detects 100% of infected pigs. A significant correlation was found between this serological method and the bacteriological data from mesenteric lymph nodes (p = 0.01). In addition, both sensitivity and specificity were high (97% and 94% respectively). The ELISA test was therefore used in a cross-sectional study on 4 farms to evaluate when pigs became contaminated: seropositive pigs were only found for the 20 week old finishing pigs. The antibody response to Salmonella in piglets was also investigated: maternal antibodies persisted until 7 weeks of age and post-Salmonella contamination seroconversion was detected from 8 weeks of age onwards.
The reliability of drug consumption studies will depend on agreement on an international unit of measurement and the provision of accurate descriptions of patterns of use. This measurement unit should permit comparisons between countries and periods of time. Different units have been proposed and published. Consumption may be expressed in terms of pharmaceutical firm turnover, therapeutic costs, weight (total weight or dose equivalent), treatment doses such as defined daily dose and prescribed daily dose, or as number of items or packages sold. The advantages and disadvantages of the different evaluation units used in veterinary medicine are reviewed.
The aim of this study is to assess the risk of contamination by Salmonella Typhimurium of pigs by nose-to-nose contact or the airborne route. Thirty twelve-week-old SPF pigs were divided into 4 groups housed in 4 different rooms: the first room contained Salmonella-free control pigs (n = 4), the second room had 10(3) CFU S. Typhimurium inoculated pigs (n = 5) and non-inoculated "contact" pigs (n = 4), the third room had pigs (n = 8) receiving potentially contaminated air from the following room through a hole (4 pigs housed in the pen situated near the hole and 4 pigs in the pen at the opposite side of the room), and the fourth room had pigs (n = 5) inoculated with 10(6) CFU Salmonella Typhimurium and also non inoculated "contact" pigs (n = 4). The "contact" and the inoculated pigs were housed in adjacent pens allowing nose-to-nose contact. The 5 pigs orally inoculated with 10(6) CFU S. Typhimurium were bacteriologically and serologically positive 1 week later and their environment was contaminated as early as 1 day pi. The faecal samples of 4 nose-to-nose contact pigs were bacteriologically positive and one of them was seropositive 5 weeks pi before the pigs were commingled. The 8 pigs housed in the third room received S. Typhimurium by an active airflow coming from the contaminated room (1000 m3/hour). Their faecal samples remained negative until 8 weeks pi but the environmental swabs taken in the room close to the airinlet were contaminated 2 days pi and positive swabs were found elsewhere in the room 5 weeks pi. Two seropositive pigs were encountered 8 weeks pi in the pen situated near the hole. Only one among the 5 pigs inoculated with 10(3) CFU had bacteriologically positive faeces 1-week pi and the 4 pigs kept in nose-to-nose contact with them remained negative. A dose of 10(3) CFU was too small to induce persistent excretion and to stimulate a humoral immune response. However, the dose of 10(6) CFU induced contamination of nose-to-nose contact pigs and contamination of the environment by airflow.