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Biomedical subjects

R F Goodwin

Publications and source records attributed to R F Goodwin.

At least 19 recordsLinked to original sources
PubMed1990

Screening pig herds for toxigenic Pasteurella multocida and turbinate damage in a health scheme for atrophic rhinitis.

The Pig Health Control Association launched a health scheme for atrophic rhinitis in 1978. For several years pig herds were monitored by scoring the degree of turbinate damage and by clinical inspections. When laboratory facilities became available for detecting toxigenic Pasteurella multocida, nasal swabs were taken from pigs in Association herds during 1988 and 1989 to determine whether the organism was present. Sows were screened routinely and in the worst affected herds, sucklers and weaners were also swabbed. In 12 of 19 herds with consistently low snout scores toxigenic P multocida were not isolated, and in 15 herds which developed higher snout scores with time toxigenic P multocida were also not found. Eleven herds had never been listed by the Association, either because their snout scores were consistently high or because they had received importations of stock from herds with high snout scores; of six of these herds with the most persistently high snout scores five showed varying degrees of the clinical signs of atrophic rhinitis, but none of the six showed evidence of infection with toxigenic P multocida, and the organism was not found in the other five herds in the group. There seems to be an overlap between the clinical and gross pathological signs of atrophic rhinitis seen in some herds not infected with toxigenic P multocida and the mild and spasmodic signs of atrophic rhinitis seen in some herds which are substantially infected with the organism.

Animals↗
PubMed1990

Detection and distribution of toxigenic Pasteurella multocida in pig herds with different degrees of atrophic rhinitis.

Four herds of pigs were selected which had different degrees of clinical atrophic rhinitis and used different specific counter-measures. In two of them, the clinical signs occurred spasmodically and were slight. The sows, suckling pigs and growing pigs in all the herds were sampled for toxigenic Pasteurella multocida. In one of the slightly affected herds (herd D), the weaners were moved to a second farm for finishing. No toxigenic P multocida were found at the breeding farm, but 50 per cent of the large growing pigs were positive. It seemed that the organism had entered only at the finishing farm and that the mild clinical signs were due to the infection starting in older pigs than usual. In the second mildly affected herd, 47 per cent of the sows and 42 per cent of the growers were infected. Three toxigenic isolates from this herd produced as severe turbinate damage experimentally in specific-pathogen-free pigs as a stock pathogenic strain. Except in herd D, toxigenic P multocida were found in all the age groups of pigs sampled. However, the pattern of distribution of the organism within the herds was not obviously correlated with the severity of the disease. In a fifth herd there were obvious cases of clinical atrophic rhinitis, with marked turbinate atrophy, from which toxi-genic P multocida were recovered in abundance. Subsequently, the clinical disease disappeared and, despite extensive and repeated sampling, the organism was not found again.

Animals↗
PubMed1990

Treatment of experimental enzootic pneumonia of the pig by norfloxacin or its 6-chloro analogue.

The 6-chloro analogue of norfloxacin (compound A) administered continuously in the feed at 400 ppm for 21 days markedly reduced the extent and activity of pneumonic lesions in pigs with pneumonia induced experimentally with an homogenate of pneumonic lung and broth cultures of Mycoplasma hyopneumoniae. Norfloxacin at 100 ppm or compound A at 200 ppm in the feed did not reduce the extent of lung lesions, although half the pigs treated with norfloxacin had lesions which appeared histologically to be healing. M hyopneumoniae was detected either by culture or immunofluorescence in the lungs of 60 per cent of the pigs treated with compound A at 400 ppm compared with all the pigs in the other groups. These results were related to the amount of drug in the lungs and body fluids during therapy. Only compound A at 400 ppm produced concentrations in the lungs and bronchial secretions exceeding the minimum inhibitory concentration against M hyopneumoniae. Mycoplasmacidal concentrations were not reached either in the lungs or bronchial secretions which might account partly for the frequent detection of M hyopneumoniae in the lungs after treatment. Drug resistance did not appear to be responsible for the persistence of M hyopneumoniae in vivo since the M hyopneumoniae isolates from the pigs after therapy were sensitive in vitro to both quinolones. As daily weight gain and feed-conversion efficiency improved in all groups of treated pigs compared with the controls, these effects were probably unrelated to the antimycoplasmal activities of the two quinolones.

Administration, Oral↗
PubMed1989

Comparison of methods for the sampling and isolation of toxigenic Pasteurella multocida from the nasal cavity of pigs.

The efficacy of detecting toxigenic Pasteurella multocida from nasal swabs of slaughtered and live pigs was assessed. The isolation of toxigenic P multocida from nasal cavities of slaughtered bacon pigs from two herds with atrophic rhinitis was reduced by immersion in the hot water tank by 25 per cent and 75 per cent. Individual sows from one of the infected herds were repeatedly swabbed to find the best method of isolating toxigenic P multocida. Toxigenic P multocida were isolated from 50 per cent of cotton swabs inoculated on to selective medium the same day. After 24 hours in the post, 45 per cent of cotton swabs placed in transport medium, 38 per cent of alginate swabs dissolved in transport medium and inoculated into mice, and 36 per cent of the dissolved swabs inoculated directly on to selective medium yielded toxigenic P multocida. These bacteria were isolated from only 25 per cent of cotton swabs held in transport medium at 10 degrees C for 48 hours to simulate prolonged postage times; from slaughtered pigs a similar reduction in isolation was seen with swabs kept for 24 or 48 hours. The reduced isolation caused by a delay before culture was associated with an overgrowth of other flora. The development of this flora was prevented by storage of swabs at 4 degrees C in the laboratory or by the use of cool boxes for postage.

Animals↗
PubMed1988

Monitoring for atrophic rhinitis: the problem of higher snout scores.

The Pig Health Control Association has run a monitoring scheme for atrophic rhinitis for 10 years. One criterion for qualification has been that the average six-monthly snout score should not exceed 0.5 (later 0.65). Eighteen qualifying herds have exceeded this limit on 56 occasions, with their average scores rising to 2.24; they were the subject of special investigations for relisting. No clinical, epidemiological or bacteriological evidence could be found to indicate that these herds were capable of developing severe atrophic rhinitis. The higher snout scores were associated with a group of recurrent husbandry factors, especially overstocking and unsatisfactory conditions in the weaner accommodation. It is possible that the upper limit for the snout score in qualifying herds could be raised considerably, thus confining bacteriological testing to more doubtful herds.

Animal Husbandry↗
PubMed1986

Eight years' experience with a register of pig herds monitored for Aujeszky's disease.

The Pig Health Control Association launched a control scheme for Aujeszky's disease in Britain in January 1978. Participating herds must not show clinical signs suggestive of Aujeszky's disease and must be serum-sampled every six months for the absence of antibodies. Importations are allowed only from listed herds, or through hysterectomy or hysterotomy, embryo transfer, or artificial insemination (the donor animals in each case having been serologically screened beforehand). During the subsequent eight years, 103 herds have qualified, and at the end of 1985, 49 herds (average size 249 sows) were listed. Despite a high degree of inter-herd stock movements, no clinical or serological evidence of Aujeszky's disease has occurred, and the disease has not arisen in any herd established from the listed herds. During the same period, Aujeszky's disease was spreading in Britain and an eradication programme began in March 1983. By the end of 1985, 502 herds not on the Pig Health Control Association's scheme comprising 421,825 pigs had been slaughtered, together with 259 serologically positive animals in 69 other herds. The Pig Health Control Association's register has provided a safe source of stock.

Animals↗
PubMed1985

Apparent reinfection of enzootic-pneumonia-free pig herds: search for possible causes.

In a control scheme for enzootic-pneumonia-free herds, run by the Pig Health Control Association, a detailed study was made of 55 herds that developed enzootic pneumonia without a simple explanation. These herds were compared with 57 herds that were still free from enzootic pneumonia in mid-1984. A high standard of precautions against the risk of infection being transferred by people and fomites seemed to confer no obvious benefit. This observation was in keeping with in vitro studies which showed that, although Mycoplasma hyopneumoniae could survive for a long time in favourable liquid medium, it could not be recovered from material such as cloth, once the culture had become dry. Under field conditions, the organism would probably cease to be infective within 48 hours. The organism survived particularly well in rain water at lower temperatures, however, and transmission via moist cold air seemed a possibility. There was a tendency for breakdowns to start in the autumn and winter, particularly in highly secure units, and several farmers associated colder misty conditions with the arrival of infection. One herd was probably infected by an imported boar and the very close proximity of foreign pigs, such as in slaughterhouse transport, seemed the most likely explanation in 15 other herds. One herd was replaced without this danger being attended to and it soon broke down again, whereas the three herds in this category that have survived after replacement all had this risk eliminated. Data was available on 37 of the 39 remaining herds to compare them with the 57 surviving herds, using a risk index based on the proximity of other pig units.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

In vitro activity of tiamulin against porcine mycoplasmas.

The activity of tiamulin against Mycoplasma hyopneumoniae, M flocculare, M hyorhinis and M hyosynoviae grown in liquid medium was assessed in vitro. With the first three of these mycoplasmas, the activity of tylosin and oxytetracycline was observed in parallel. Tiamulin was more active against M hyopneumoniae and M flocculare, but there was less disparity between the three antibiotics with the strain of M hyorhinis tested. Tiamulin was notably more active against M hyosynoviae than against M hyopneumoniae. It was more difficult to suppress M hyopneumoniae than the other mycoplasmas with tiamulin. This persistence of M hyopneumoniae was more striking when M hyopneumoniae and M hyosynoviae were tested in parallel.

Animals↗
PubMed1984

Use of tiamulin in a herd of pigs seriously affected with Mycoplasma hyosynoviae arthritis.

Tiamulin hydrogen fumarate has been shown to be highly active in vitro against Mycoplasma hyosynoviae, an organism that causes arthritis in pigs. A gilt-multiplier herd with a history of this condition was selected to evaluate the efficacy of tiamulin in vivo for the treatment of this disease. The presence of M hyosynoviae was confirmed by its isolation from two typically affected cases. A field trial was carried out on clinically affected pigs, using tiamulin at 10 mg and 15 mg/kg bodyweight given by injection for three consecutive days, by comparing their weight gains and reduction in lameness scores during a seven day trial period (days 0 to 7) with those of negative untreated controls and positive controls injected with lincomycin at 10 mg/kg bodyweight for three days. Both of the tiamulin treatment levels appeared to be effective, as there were marked improvements in weight gains and reduction in lameness scores in comparison with the negative controls. The improvements were similar to those achieved with the positive control, lincomycin.

Animals↗
PubMed1984

Apparent reinfection of enzootic-pneumonia-free pig herds: early signs and incubation period.

Since 1959, the Pig Health Control Association (PHCA) has run a national health-control scheme for pig herds believed to be free from enzootic pneumonia. During this time, many herds developed this disease without a simple explanation. From 1968, 55 such unexplained breakdowns have been studied in detail. The first signs in 50 breakdowns were either coughing in growing pigs (52 per cent of outbreaks), illness in adult stock (34 per cent of outbreaks) or pneumonia in routinely slaughtered pigs (14 per cent of outbreaks). In some outbreaks, enzootic pneumonia appeared to grow out of a pre-existing respiratory infection, which was not identified as enzootic pneumonia, in suckling pigs, suggesting that either Mycoplasma hyopneumoniae was already present in a latent state, or it more readily seeded damaged respiratory tracts from outside. In three outbreaks of this type, where pathological material was collected during the transition period, no laboratory evidence was obtained for the presence of M hyopneumoniae in the primary respiratory disease. Analysis of breakdowns in two national testing stations indicated that clinical/pathological signs might not develop until three to five months after the introduction of an infected group of weaners. It is possible, therefore, that a pig herd might not show obvious signs of the disease until up to six months or more after initial infection. There was little evidence to indicate that unexplained breakdowns arose from long term latent infection in other herds from which stock had been imported. There was considerable evidence, however, to suggest that breakdowns arose from extraneous sources.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Monitoring for swine dysentery: six years' experience with a control scheme.

A control scheme for swine dysentery was initiated in Britain by the Pig Health Control Association in January 1978. To qualify, herds must not show clinical signs suggestive of swine dysentery or, if any suspicious signs arise, laboratory tests must be negative for Treponema hyodysenteriae. In addition, a range of pharmaceutical compounds that might mask the disease or its laboratory diagnosis may not be used routinely after weaning, either for treatment or as food additives. Qualifying herds can import pigs only from other qualifying herds or via hysterectomy/hysterotomy or embryo transfer methods; artificial insemination is also permitted. During the first six years, 91 herds qualified at some stage, and at the end of 1983, 56 herds (average size 200 sows) were still listed. By this date, 72 herds had imported stock from 36 other qualifying herds; despite this degree of inter-herd connection, no evidence of swine dysentery has occurred within the scheme since its inception, nor has this disease appeared in herds established entirely from listed herds. It seems, therefore, that freedom from swine dysentery (unlike enzootic pneumonia) can be readily maintained in a controlled group of pig herds identified by these monitoring methods.

Animal Feed↗
PubMed1983

Monitoring for atrophic rhinitis: five years' experience with a pilot control scheme.

A pilot control scheme for atrophic rhinitis was initiated in Britain by the Pig Health Control Association in January 1977. To qualify, herds must have maintained a low degree of turbinate damage and not shown clinical signs of atrophic rhinitis over a period of at least two years. Qualifying herds can import pigs only from other qualifying herds or via hysterectomy/hysterotomy methods. During the first five years, 45 herds qualified at some stage, and at the end of 1982, 34 herds (comprising about 7200 sows) were still listed. Although the scheme is not related to particular infectious agents, atrophic rhinitis has not appeared within it or in herds established entirely from listed herds, despite the fact that 31 of the 45 qualifying herds had imported stock from 15 other qualifying herds.

Animals↗
PubMed1977

Apparent re-infection of enzootic-pneumonia-free pig herds: specificity of diagnosis.

In a control scheme for enzootic-pneumonia-free herds, 43 herds developed enzootic pneumonia, as judged by non-specific clinical and pathological criteria over 10 years. Material for cultural examination was obtained from 32 of these outbreaks, and Mycoplasma suipneumoniae was identified in 28 of them. The four failures occurred before 1971 at a time when the cultural techniques were clearly inferior. Since 1971 M suipneumoniae has been isolated from all the 17 outbreaks sampled for this purpose. Two of the outbreaks from which M suipneumoniae was not recovered, and three further outbreaks, were closely connected with outbreaks from which M suipneumoniae had been isolated (to make 33 out of 35). The remaining eight outbreaks (in which isolations of M suipneumoniae were not attempted) were clinically and pathologically consistent with the pattern of the others. Hence, there is reason to believe that during this period the outbreaks of respiratory disease simulating enzootic pneumonia in the control scheme have probably all been associated with the presence of M suipneumoniae.

Animals↗