Characteristics of a flubendazole resistant isolate of Oesophagostomum dentatum from Germany.

Two controlled tests were performed to investigate the benzimidazole resistance of a nodular worm isolate "GIBZ" from a pig breeding farm in Germany. In Trial I, groups of five pigs, artificially infected with Oesophagostomum larvae isolated from that farm were treated with flubendazole at a single dose of 5 mg kg(-1) bodyweight (BW) or remained untreated. In Trial II, three groups of three pigs each infected with larvae after a further laboratory passage of this isolate were treated with flubendazole either at a single dose of 5 mg kg(-1) BW or at a divided dose of 1.5 mg kg(-1) BW daily for 5 consecutive days, or with fenbendazole at a single dose of 5 mg kg(-1) BW, the fourth infected group remained untreated. The respective doses of anthelmintics were mixed with a small amount of feed and administered to individual pigs in both trials. Fecal egg counts before and after treatment and post-mortem worm burdens 7 days after (last) treatment were examined to assess the anthelmintic efficacies. Only infections with Oesophagostomum dentatum were found in both trials. In Trial I, the mean worm count reduction by flubendazole was 30% as compared to the untreated controls. In Trial II, flubendazole administered at a single or divided dose reduced the mean worm burden by 0 and 85%, respectively, whereas fenbendazole was 100% effective. These results establish resistance to flubendazole in the isolate "GIBZ" of O. dentatum. The failure to reveal side resistance to fenbendazole may be explained by that the currently recommended dose rate of this compound is supra-optimal for porcine nodular worms.     

Prevention of pleuropneumonia in pigs by in-feed medication with sulphadimethoxine and sulphamethoxazole in combination with trimethoprim

The prophylactic effect of in-feed medication of conventional pigs with sulphadimethoxine (SDM), sulphamethoxazole (SMX), and trimethoprim (TMP) was tested by using an Actinobacillus pleuropneumoniae infection model. In each of five experiments, six pigs were given medicated feed twice daily and three pigs received antibiotic-free feed and served as positive (unmedicated, infected) controls. The following drugs or drug combinations were tested (in mg per kg feed): 500 SDM + 100 TMP, 500 SMX + 100 TMP, 125 SMX + 25 TMP, 125 SMX (alone) and 25 TMP (alone). After six days of feed medication, all animals were endobronchially inoculated with A. pleuropneumoniae in a dose of 1-3.10(4) colony-forming units (CFU). The response to the challenge in all control pigs was characterized by fever, lethargy, anorexia, reduced water consumption, and laboured breathing. At autopsy all controls manifested a fibrinous haemorrhagic pleuropneumonia. In-feed medication with 500 SDM + 100 TMP, 500 SMX + 100 TMP as well as 125 SMX + 25 TMP resulted in an effective protection against the challenge in all treated animals. After consumption of feed medicated with 125 mg per kg SMX or 25 mg per kg TMP, pleuropneumonia was evident in all challenged pigs. The results of this study indicate an in vivo potentiation of SMX and TMP in pigs against this respiratory tract pathogen.     

Laboratory investigations on pigs with the new anthelmintic fenbendazole.

The efficacy of fenbendazole was investigated in piglets infected artificially with Hyostrongylus rubidus and Oesophagostomum spp. After administration of 3.5 mg/kg, five-day-old stages of H rubidus were reduced by 72.5 per cent; an effect of 78.4 per cent, 96.0 per cent and 100 per cent was achieved against five-day-old, 16-day-old and 42-day-old stages, respectively, of H rubidus using a dose of 5 mg/kg. A 55 per cent effect was obtained against five-day-old stages after the administration of 3.5 mg/kg. A dose of 5 mg/kg reduced five-day-old, 16-day-old and 42-day-old stages of Oesophagotomum spp by 72.6 per cent, 44 per cent and 100 per cent respectively.     

Laboratory investigations in sheep with a new anthelmintic.

The efficacy of fenbendazole against the following gastrointestinal nematodes was tested in experimentally infected lambs: O circumcincta, H contortus, T colubriformis and N filicollis. As low a dose as 0.5 mg per kg reduced the egg output of a patent infection with H contortus and T colubriformis by 85 per cent to 100 per cent. A dose of 3.5 mg per kg has a 100 per cent effect on three or 10-day-old stages of H contortus and one of more than 99 per cent or 100 per cent T colubriformis. The same dose reduces seven-day-old stages of O circumcincta and N filicollis by more than 94 per cent or 100 per cent, while 10 mg per kg produces a 100 per cent elimination of seven-day-old stages of O circumcincta. In field trials and efficacy of more than 99 per cent was determined after oral dosage with 5.0 mg per kg against Ostertagia, Haemonchus, Trichostrongylus, Cooperia, Nematodirus and Chabertia. Fenbendazole has a wide therapeutic-toxic dose ratio. Discoloration of the wool does not occur. Fenbendazole can be administered as a drench or with the feed.     

中药肠炎康治疗猪大肠杆菌病的临床试验

[摘 要] 为了验证中药肠炎康对猪大肠杆菌的临床效果,对猪人工感染大肠杆菌进行治疗性试验。利用大肠杆菌O301对试验组猪进行人工感染后,分为肠炎康低、中、高,庆大霉素治疗试验。结果表明拌入饲料肠炎康（拌料10g/kg ,连用3d）治疗猪大肠杆菌病疗效可靠,效果明显。对人工感染引起的猪大肠杆菌病治愈为86.7%,有效率100%,并能显著降低猪死亡率。     

Distribution and biology of Ornithodoros erraticus in parts of Spain affected by African swine fever

Ornithodoros erraticus was found in 30.7 per cent, 35.0 per cent and 71.0 per cent of the pig-pens sampled in the provinces of Salamanca, Badajoz and Huelva in which African swine fever is a problem in the rearing of Iberian pigs. Between 38 and 65 per cent of the pig-pens in these areas are now abandoned and their populations of O erraticus are extinct or becoming so because they can no longer feed on pigs, which in Spain are their main hosts. The abandonment of pig-pens has resulted in the elimination of most soft ticks infected with the virus of African swine fever, and means that the distribution of ticks is now irregular and focal. Another factor affecting their distribution is the kind of soil on which the pig-pens are located. In abandoned pig-pens, the adults and large nymphs survive for about five years or longer when animals occasionally enter them. Hungry tick populations may transmit African swine fever when feeding in winter, whereas the populations that have continuous access to pigs do not feed until the pig-pens reach a temperature of 13 to 15 degrees C. In the latter populations, each stage exhibits a single annual peak of activity, which implies that the development from larva to adult takes two to three years. Pigs may die as a result of the bites, but on no occasion were 100 per cent of the fasting ticks seen to feed, even though they had the opportunity of doing so. This may hinder the eradication of this soft tick from infested pig-pens.     

Anticoccidial efficacy of diclazuril in pheasants

Diclazuril, a new anticoccidial drug, was tested in young pheasants artificially infected with the three most common pathogenic species of Eimeria, E colchici, E duodenalis and E phasiani. In two replicate experiments each with 40 birds the mortalities in the infected controls were 50 and 25 per cent. Diclazuril was administered in the feed at dose levels of 1, 2 and 4 ppm from the day before the inoculation of coccidia until the end of the test on day 6 after infection. The 1 ppm dose failed to inhibit the development of the parasite completely, as was shown by a reduction of the weight gain of the birds and the output of a small number of oocysts. Diclazuril at 2 or 4 ppm adequately controlled the infection, with weight gains similar to those of the uninfected controls. At all dose levels, mortality, intestinal lesions and diarrhoea were prevented.     

Evaluation of the safety of flubendazole premix in swine

Forty-eight pigs were used to evaluate the safety of flubendazole, given as a 6% rice-hull premix. In 1 experiment, flubendazole was administered orally to 16 pigs daily for 5 days at dosages of 10 or 20 times the recommended rate. In a 2nd experiment, flubendazole was administered in the feed to 18 pigs daily for 15, 16 or 17 consecutive days at dosages of 1, 3 and 5 times the recommended rate. The remaining 14 pigs received a placebo premix and served as controls. Clinical observations were made each day, and body weights and clinical laboratory values were monitored before, during and after the treatment period. In the 2nd experiment, all pigs were necropsied 1 day after the last day of treatment. Clinical signs during the experiments consisted of soft/fluid feces, observed in pigs from all groups, and occasional vomiting from 3 pigs in the group given the 3X-exaggerated dose. Statistical differences in the frequency of loose feces and vomiting were not detected between the placebo group and flubendazole-treated groups. There were no other abnormal signs noted throughout either experiment. Results of serum chemistry analysis, hematologic examination, and histopathologic evaluation revealed no evidence of drug-related toxicity.     

Evaluation of fenbendazole as an extended anthelmintic treatment regimen for swine

Fenbendazole was given in the feed to swine at a cumulative dosage of 9 mg/kg of body weight over a period of 3, 6, and 12 days to compare efficacy. Four treatment groups of ten 2- to 3-month-old pigs each, with a mean of 15 kg of body weight per group, received 3 mg of fenbendazole/kg/day for 3 days, 1.5 mg/kg/day for 6 days, 0.75 mg/kg/day for 12 days, and no medication. Medicated feed was scheduled so that all treated pigs reached the last day of treatment on the same day, thus making the time between the last treatment and necropsy equal for all groups. Ascaris suum and Trichuris suis were the target species, their presence before treatment being determined by fecal egg counts and at necropsy by worm counts. At necropsy, 9 control pigs were infected with A suum (mean of 18.0 worms/pig), and all control pigs had T suis infection (mean of 36.5 worms/pig). All 3 treatment schedules were 100% effective in removal of A suum; and for T suis, the 3-day regimen was 100% effective, the 6-day regimen, 99.2%, and the 12-day regimen, 91.0%.     

The effect of fenbendazole on nematode parasites in experimentally infected lambs.

Fenbendazole given orally to experimentally infected lambs at a dose rate of 5 mg per kg was found to be 100 per cent effective against three and 10-day larave and also against 20-day adults of H contortus, O circumcincta, N battus and T colubriformis. The same dose was also 100 per cent effective against 10-day, 17-day larvae and 27-day adult D filaria.     

The synergistic activity of tiamulin and chlortetracycline: in-feed treatment of bacterially complicated enzootic pneumonia in fattening pigs

The antibacterial effects of a combination of tiamulin and chlortetracycline in vitro against a number of field isolates of Pasteurella multocida, Haemophilus pleuropneumoniae and Bordetella bronchiseptica were examined. There was a marked synergism between the two antibiotics against all eight isolates of P multocida, against seven of nine isolates of H pleuropneumoniae and against the single strain of B bronchiseptica tested. Two field trials were carried out on a herd with a history of complicated enzootic pneumonia where the presence of Mycoplasma hyopneumoniae and P multocida had been established and subsequently the presence of H pleuropneumoniae was discovered. Feed containing tiamulin at 100 ppm combined with chlortetracycline at 300 ppm was given for seven days to pigs affected with pneumonia, and the results were compared with untreated controls and pigs receiving chlortetracycline at 300 ppm. There was a follow-up observation period of three weeks when all groups received unmedicated feed. During the medication period the combination treated groups showed a statistically significant increase in average daily weight gain of 156 g (20.4 per cent) and in feed conversion efficiency of 0.576 (20.8 per cent) and a numerical improvement in average disease score in comparison with the untreated controls. These improvements were approximately double those observed in the groups treated with 300 ppm chlortetracycline which showed improvements of 93 g (12.2 per cent) in average daily gain and 0.301 (10.9 per cent) in feed conversion efficiency. During the following three weeks most of the initial gains were lost, probably owing to the reinfection of the treated groups by the untreated controls.     

Infection of cattle by airborne foot-and-mouth disease virus: minimal doses with O1 and SAT 2 strains

Equipment has been constructed and methods developed for exposing individual cattle to two strains of foot-and-mouth disease (FMD) virus in aerosols to determine the minimal infective dose by the respiratory route. The aerosols used were produced either artificially by a spinning-top aerosol generator, in which case they were of homogeneous small particle size (less than 3 micron in diameter) or else they were derived naturally from infected pigs, in which case the particles were heterogeneous in size. Two strains of FMD virus were used: an O1 strain of UK origin and a SAT 2 strain from South Africa. The lowest doses which initiated infection were 12.5 TCID50 of O1 BFS virus and 25 TCID50 of SAT 2 virus, infectivity having been assayed in primary bovine thyroid cell cultures. Following exposure to low doses of virus (range 12 to 316 TCID50) 33 per cent of the cattle exposed to O1 BFS virus and 27 per cent exposed to SAT 2 virus were infected but did not develop detectable vesicular lesions.     

Control of salmonella infections in broiler chickens by the acid treatment of their feed

In three experiments a solution of formic acid (Bioadd) was added to feed 'naturally' contaminated with salmonellas. In two of them no salmonella infections were demonstrated in broiler chickens given feed containing 0.6 per cent (w/w) of the formic acid solution for seven weeks and in the third the infection rate was reduced considerably. In four other experiments the feed was contaminated artificially with between 1 and 47 Salmonella kedougou/g and a second product (BPO12), consisting of a mixture of formic acid and propionic acid, was evaluated. When it was added at 0.5 to 0.68 per cent (w/w) only one of 30 groups of 10 to 12 birds became infected with S kedougou by two weeks of age, compared with 22 of 27 control groups. The treatment of the feed with BPO12 one week before the addition of the salmonellas prevented the establishment of infection in chicks given the treated feed, indicating that acid treatment will provide protection against subsequent recontamination of the feed with the organisms. The isolation rate of S kedougou from artificially contaminated feed treated with BPO12 was reduced only slightly but the feed was apparently 'safe' for the birds which consumed it.     

沙拉沙星对实验性猪链球菌病及猪水肿病的药效学

将兽医专用氟喹诺酮类药物沙拉沙星以不同治疗方案分别对实验性猪链球菌病和猪水肿病进行药效学研究。在每天总剂量相同的情况下 ,每天 1次与每天 2次给药取得了较好而相似的疗效 (P>0 .0 5 ) :对猪链球菌病 ,每天总剂量为 10 m g/ kg时 ,肌注给药的治愈率分别为 10 0 %和 90 %,但在迅速改善临床症状方面 ,每天 1次给药优于每天 2次(P<0 .0 5 ) ;对猪水肿病 ,每天总剂量为 5 mg/ kg时 ,肌注给药的治愈率均为 10 0 %。结果表明 ,在总剂量相同时 ,以大剂量、长间隔与以较小剂量、短间隔治疗实验性猪链球菌病与猪水肿病 ,均取得相当的疗效。     

Epidemiological characteristics and financial costs of the 1997 foot-and-mouth disease epidemic in Taiwan

Between March and July 1997, a devastating outbreak of foot-and-mouth disease (FMD), serotype O, occurred in pigs in Taiwan. A total of 6,147 pig farms with more than 4 million pigs were infected, and 37.7 per cent of the pigs in Taiwan either died (0.18 million pigs) or were killed (3.85 million pigs). The epidemic reached its peak during the fifth week after it was first recognised. During the eighth and ninth weeks, a two-dose blanket vaccination programme was instituted which led to a large reduction in new outbreaks. Except for two cities, the whole of Taiwan was declared an FMD-infected zone. During the four months in which new farm outbreaks occurred, 21.7 per cent of the pigs on infected farms showed clinical signs, and there was an overall mortality of 3.95 per cent. During the early stages of the epidemic, the incubation period was as short as 24 hours and the case fatality rates for suckling piglets reached 100 per cent. The financial cost of the epidemic was estimated at US$ 378.6 million, including indemnities, vaccines, carcase disposal plus environmental protection, miscellaneous expenses, and loss of market value. Owing to the ban on exports of pork to Japan, it is estimated that the total economic cost to Taiwan's pig industry will be about US$ 1.6 billion.     

Streptococcal meningitis in pigs: field trial to study the prophylactic effect of trimethoprim/sulphadiazine medication in feed

Half the progeny in a 200-sow herd (2045 pigs) was given feed medicated with 500 g/tonne of a 1:5 trimethoprim/sulphadiazine mixture from three to nine weeks of age. The other half (1989) acted as controls. The trial lasted 12 months. No difference was observed between the two groups in the incidence of streptococcal meningitis and the morbidity and mortality from all disease causes during the growing/fattening periods did not differ significantly. The main diseases encountered were pneumonia (7.24 per cent), streptococcal meningitis (5.12 per cent), leg and foot disorders (3.34 per cent) and the after-effects of vices (1.86 per cent). The resistance of faecal coliforms to trimethoprim was studied during the six-week period of trimethoprim/sulphadiazine feeding. Faecal coliforms in both medicated and non-medicated groups developed almost 100 per cent resistance. However, resistance developed more slowly in the untreated pigs. The medicated pigs showed a small overall improvement in feed conversion rate up to 18 weeks of age mainly because of a marked improvement between three and six weeks.     

Characteristics of commercial pig farms in Great Britain and their use of antimicrobials

A mail survey of 1889 pig producers in Great Britain with more than 100 sows or more than 1000 pigs was carried out to investigate their use of antimicrobials and other health-related management practices. The response rate was 25.5 per cent. Antimicrobials were most commonly administered in feed. Depending on the production system, between 60 and 75 per cent of the farms had used antimicrobials in their weaner rations and 20 to 62 per cent had used them in their grower rations. Antimicrobial injections had been used on 59 per cent of the farms. The use of antimicrobials in pigs of different age groups was variously associated with the scale of production, membership of a quality assurance scheme, the use of vaccination and whether the farmer thought the farm environment could be improved. Half the respondents (49 per cent) indicated that they used growth promoters in their weaners, but fewer used these in their growers (45 per cent) and finishers (34 per cent). Although 63 per cent of the farmers felt that the continued use of antimicrobials for disease prevention was justified, only 21 per cent felt that their continued use as growth promoters was justified.     

Efficacy of diclazuril in the prevention and cure of intestinal and hepatic coccidiosis in rabbits

The efficacy of diclazuril against intestinal and hepatic coccidiosis was studied in artificially infected rabbits. Prophylaxis against intestinal coccidiosis was evaluated using a mixed infection of Eimeria intestinalis, Eimeria magna and Eimeria perforans. Continuous medication in the feed at 1 p.p.m. was 100% effective in reducing oocyst output and faecal scores, and weight gain and feed efficiency were normal. Hepatic coccidiosis induced by Eimeria stiedai was prevented at 0.5 and 1 p.p.m. as shown by negative oocyst counts, normal liver weight, absence of liver lesions, and normal body-weight gain and feed efficiency. Medication at 1 p.p.m. for 7 consecutive days during the prepatent phase of hepatic coccidiosis resulted in large reductions in oocyst counts and lesion scores with a normal liver weight and growth performance. Diclazuril at 1 p.p.m. in the feed prevented both intestinal and hepatic coccidiosis in rabbits and can be advocated for safe mass medication.     

Performance of pigs with mixed nematode infections before and after ivermectin treatment

Ninety crossbred parasitized pigs were used in two controlled experiments to compare performance before and after ivermectin treatment. Four groups of 15 pigs were sequentially infected with 2000 Ascaris suum, 10,000 Oesophagostomum spp. and 10,000 Strongyloides ransomi beginning at average pig weights of either 38 kg (Experiment I) or 14 kg (Experiment II). Two infected groups of pigs were treated with ivermectin on Day 34 (Experiment I) or 37 (Experiment II) of the experiments and all pigs were fed to slaughter weights of approximately 100 kg. Average daily gain (ADG) of heavier ivermectin-treated pigs was greater than that of infected non-treated pigs (P less than 0.03) and feed conversion was numerically greater by 5% (P greater than 0.10). ADG was not different between lighter treated or non-treated pigs, but feed conversion was numerically 4% greater in ivermectin-treated compared to non-treated pigs (P greater than 0.10). No differences existed in carcass dressing percentage among the three groups of heavier pigs, but among the lighter groups ivermectin-treated pigs had a higher dressing percentage (P less than 0.03) than infected non-treated or control pigs. Results of the calculation of production costs based on combined data from the two experiments for the post-treatment period, including feed, drug and maintenance costs, indicate that the production cost for ivermectin-treated pigs was $1.53 per pig less than that for infected non-treated pigs when the cost for each group to attain control pig weights is compared with the actual cost for control pigs.     

Some consequences of the ingestion by young and growing pigs of feed contaminated with ergot.

Growing pigs were fed freshly milled ergot sclerotia (Claviceps purpurea Fr (Tul)) from North American wheat containing 0-31 per cent of total alkaloids of which 30 per cent was ergotoxine, 30 per cent ergosine, 20 per cent ergotamine and 20 per cent other ergot alkaloids. Pigs were induced to ingest a diet heavily contaminated with ergot (10 per cent w/w). The presence of ergot reduced feed intake and growth of the pigs, but there was no evidence of peripheral necrosis, of internal or external haemorrhage, or of changes in haemotological characteristics. Balance experiments in which the diet was contaminated with 4 per cent (w/w) of ergot showed that 90 per cent of the alkaloids were absorbed by the pigs, but none could be detected in tissues or urine. The ingestion of ergot did not affect the digestibility of the diet, but the urinary excretion of nitrogen was increased and the retention of nitrogen reduced. The presence of ricinoleic acid was shown to be a useful diagnostic feature of ergot contamination of diets, digesta and faeces; it was not found in body tissues.