A field trial to assess the therapeutic and prophylactic effect of a foot rot vaccine in sheep

An 18-week field trial was conducted on a sheep ranch to evaluate the therapeutic and prophylactic effect of a commercial foot rot vaccine. Two hundred sheep were included in the study, 100 with detectable foot rot lesions and 100 without. Approximately 50 sheep from each group were selected randomly and vaccinated twice against foot rot at a 6-week interval in the late spring 1984; the remaining sheep acted as nonvaccinated controls. Therapeutic effect of the vaccine was demonstrated by a cure rate of 53% in vaccinated, foot rot-affected sheep vs a cure rate of 19% in nonvaccinated, foot rot-affected sheep. Prophylactic effect of the vaccine was demonstrated by a foot rot prevalence at the end of the 18-week period of 9% for vaccinated sheep vs 53% for nonvaccinated sheep. Associations of foot rot lesions and vaccination with body condition were found to be significant, as was the association between foot rot lesions and mortality.     

坏死杆菌白细胞毒素作为腐蹄病亚单位疫苗候选抗原的研究前景

腐蹄病（foot rot）是侵害反刍动物趾间皮肤及深层软组织为主的,严重影响奶牛生产性能和产奶质量的一种常见疾病。由于传统的灭活菌苗具有免疫效果差、副反应严重及大量生产困难等缺点,使腐蹄病基因工程疫苗的研究成为热点。笔者对坏死杆菌白细胞毒素作为腐蹄病亚单位疫苗候选抗原研究的最新进展进行综述,希望为腐蹄病亚单位疫苗的研究提供参考。     

Importance of pilus-associated antigen in Bacteroides nodosus vaccines

The performances of two cellular vaccines, one sparsely piliated and the other well piliated, were compared on irrigated pasture with those of vaccines containing their respective, purified pili. There were statistically significant differences among the four vaccines in the mean numbers of feet per sheep which developed severe foot rot during 27 weeks of exposure. The incidence of severe foot rot was significantly lower in the two pili-vaccinated groups than in the group vaccinated with well-piliated cells, which were in turn substantially more effective than the sparsely piliated. However, the two pili vaccines did not prevent infection of the interdigital skin so that the differences in vaccine performance were much less marked when interdigital skin lesions were included. The number of feet affected by blowfly strike was closely associated with the presence of the most severe lesions and consequently there were far fewer struck feet in the two pili vaccine groups than in the two cellular vaccine groups. Analysis of serum agglutinin titres led to the same assessment of vaccinal efficacy as that derived from the analysis of severe foot rot lesions. Individually the agglutinin response to vaccination was not universally associated with resistance or susceptibility to severe foot rot but mean titres were significantly higher in the two pili vaccine groups than in the highly piliated-cell vaccine group, which were all in turn significantly higher than in the poorly piliated-cell vaccine group.     

Antibody responses of sheep vaccinated with foot rot vaccines

Enzyme-linked immunosorbent assay (ELISA) and crossed immunoelectrophoresis (IEP) were used to investigate antibody responses of sheep vaccinated with a double adjuvanted or single adjuvanted commercial foot rot vaccine. ELISA detected an antibody response of greater magnitude to the double adjuvant vaccine compared with the single adjuvant vaccine. Sera from sheep vaccinated with double adjuvant vaccine recognised at least six antigens of Bacteroides nodosus in crossed IEP while sera from the single adjuvant vaccinated sheep recognised one antigen. The use of non-denatured antigens of B nodosus in ELISA and crossed IEP enabled quantitative comparisons of antibody responses to the different foot rot vaccines to be made.     

An economic evaluation of various treatments for contagious foot rot in sheep, using decision analysis

Two decision analysis models were constructed to identify the cost-effectiveness of treatment and/or prevention regimens for ovine foot rot through a systematic evaluation approach of 2 consecutive phases. The first model evaluated the cost-effectiveness of examining the sheep for foot lesions and the use of 1 of 32 treatment regimens when lesions were present. The second model evaluated the 6 most cost-effective treatment regimens from the first model with or without a preventive measure (in this case, vaccination) to determine the most cost-effective approach to preventing/treating foot rot in a single year. Three prevalence levels of foot rot were used. In addition, 3 levels of reduced production attributable to foot rot were used. Threshold analysis, a form of sensitivity analysis, was used to evaluate allowable variations in the success rates and cost of treatments/prevention where the outcome of the models remains unchanged. Of the 32 treatment regimens tested in this model, the use of 10% zinc sulfate applied to the feet of sheep with foot rot was the most cost-effective regimen, regardless of the prevalence levels of the disease or its impact on productivity. In the second model, the use of vaccination with paring of the feet, as a preventive measure, followed by a treatment of the sheep that were still infected, was less cost-effective than to treat only the sheep with foot lesions and disregard prevention. This was true regardless of the prevalence levels of the disease or its impact on productivity.     

Comparison of alum-absorbed or non-alum-absorbed oil emulsion vaccines containing either pilate or non-pilate Bacteroides nodosus cells in inducing and maintaining resistance of sheep to experimental foot rot

Highly pilate (P) or non-pilate (NP) cells of Bacteroides nodosus were compounded into oil emulsion (O) either with or without prior absorption onto alum (A). The abilities of these four preparations (referred to as PAO, NPAO, PO and NPO vaccines) to stimulate antibody production and to protect sheep from foot rot were compared. Two injections of PAO vaccine protected sheep against homologous challenge 12 weeks after the second dose by PO, NPO and NPAO vaccines were less effective. Sheep were protected against homologous challenge for 14 weeks after a single dose of PAO vaccine and for 22 weeks after three doses; an ameliorative effect was still evident 40 weeks after the third dose. Protection against challenge with two heterologous strains was demonstrated at six weeks after three doses of vaccine. A numerical system of scoring the lesions also confirmed that foot rot in vaccinated sheep challenged outside the 'protective' period of the vaccine was somewhat less severe than in controls. PAO vaccine induced much higher and more persistent titres of agglutinins than the other vaccines tested. There was a relationship between agglutinin titres and resistance to homologous challenge.     

Humoral responses to a multivalent vaccine in age-matched lambs of different bodyweight and nutrition

K-agglutination, pilus-enzyme-linked immunosorbent assay (ELISA) and outer membrane protein-ELISAs were used to assess humoral responses after vaccination with a commercial, multivalent, ovine foot rot vaccine (Dichelobacter nodosus whole cells) in three groups of nine-month-old lambs of markedly different bodyweight, nutritional history and dietary protein supply. Mean bodyweights of lambs in low (L), medium (M) and high (H) bodyweight/nutrition groups were 22, 32 and 48 kg, respectively, at the time of vaccination. Few significant differences in humoral responses to vaccine antigens were found between groups. However, lambs in group H tended to have lower levels of antibody to a greater number of component antigens than did lambs in the other groups. These results suggest that low bodyweight due to poor nutrition is unlikely to affect the response of sheep to multivalent foot rot vaccines.     

Effect of pilus dose and type of Freund's adjuvant on the antibody and protective responses of vaccinated sheep to Bacteroides nodosus

Groups of sheep were immunised twice with one or other of six vaccines consisting of purified pili from Bacteroides nodosus at three dose levels (10, 38 and 154 micrograms) and emulsified with either complete (CFA) or incomplete Freund's adjuvant (IFA). Beginning one month after vaccination the sheep were homologously challenged on irrigated pasture, with naturally transmitted foot rot for a period of 26 weeks. Statistical analyses of the number of feet per sheep with severe foot rot demonstrated that there was a significant effect of vaccinal dose but neither an adjuvant effect nor an interaction between dose and adjuvant. Similar conclusions were reached when the titres of antipilus agglutinins in the serum were analysed. By both criteria the responses to doses of 154 and 38 micrograms of pili were significantly better than to 10 micrograms, but not significantly different from each other. The IFA vaccines caused less reaction at the sites of injection than the CFA vaccines and within the former the vaccines containing 10 and 38 micrograms pilus produced less reaction than those containing 154 micrograms. Hence a vaccine containing 38 micrograms of purified pili in IFA is nearly optimal for homologous protection against severe foot rot and is acceptable in terms of the reaction at the injection site.     

The use of an autogenous Dichelobacter nodosus vaccine to eliminate clinical signs of virulent footrot in a sheep flock in Bhutan

An outbreak of virulent footrot was investigated in a flock of 605 Merino cross-bred sheep in Bhutan. Conventional control methods in the preceding eight years had reduced its prevalence from 36-79% in different components of the flock to about 15% overall. Only one serogroup (B) of Dichelobacter nodosus was identified among 40 isolates cultured from affected sheep. A vaccine prepared from this strain was used in a pilot trial to compare the response of 14 treated and 14 untreated sheep. All affected, vaccinated animals in this trial healed quickly and were protected against re-infection while additional cases developed among untreated sheep during a period favourable for the spread of footrot. The serogroup B vaccine was administered to the whole flock for two successive years. No other footrot treatment was given during these or subsequent years. The whole flock was examined three times, foot by foot, for two years and twice yearly for another two years. When vaccination began there were 88 affected sheep in the flock, an affected sheep being defined as an animal with a foot-score of 2 or greater in one or more feet. There were neither affected sheep in the flock 30 days after the first dose of vaccine nor were any identified in later inspections. Virulent footrot, originating from the farm under investigation, persisted in neighbouring village flocks during this period. It was concluded that whole flock specific D. nodosus vaccination made a major contribution to the elimination of all clinical signs of footrot from the flock of 605 sheep where the condition had previously persisted for 10 years.     

Genetic-associated resistance to foot rot in selected Targhee sheep

Three Targhee rams obtained from the Ohio Agricultural and Experimental Station had been identified as foot rot resistant on the basis of results of challenge exposure. In the first breeding trial, when rams were bred to 20 foot rot-susceptible ewes, the percentages of foot rot-resistant offspring from the 3 foot rot-resistant rams were 68, 82, and 100, compared with 55 and 60 for foot rot-resistant offspring from 2 known foot rot-susceptible rams. In the second year, the foot rot-resistant rams were mated with ewes of unknown foot rot status. The foot rot-resistant status of their lambs was compared with that of range-raised lambs whose parents' foot rot status was unknown. During the first year, challenge exposure to the disease consisted of confinement of the lambs in moist or wet pens with sheep affected with the naturally acquired disease. This protocol was repeated for lambs born during the second-year breeding trial. In addition, the right front foot of each lamb was inoculated with a broth culture of Bacteroides nodosus. During the second year, when data that included infected feet from all lambs were analyzed, 41% of the progeny of the foot rot-resistant rams and 17% of the offspring of parents of unknown foot rot status were unaffected by the disease. When the B nodosus-inoculated foot was not included in the analysis, however, 61% of the progeny of the foot rot-resistant rams and 29% of the others were unaffected. The resistance to foot rot undoubtedly is hereditary. The mechanism of resistance may be in the interdigital skin.(ABSTRACT TRUNCATED AT 250 WORDS)     

新药物对奶牛感染性蹄病动物模型临床疗效试验

为探索治疗奶牛感染性蹄病的新药物,以患蹄病的绵羊为奶牛感染性蹄病的动物模型进行临床治疗试验。试验药物是针对奶牛感染性蹄病痛原特点研制的5种配方,即配方Ⅰ～配方Ⅴ。选择自然感染蹄病的绵羊50只,随机分为7个组,各组羊只分别为配方Ⅰ组6只、配方Ⅱ组7只、配方Ⅲ组10只、配方Ⅳ组9只、配方Ⅴ组8只、药物对照组5只、空白对照组5只。结果表明,在本试验药物组中,临床疗效依次为配方Ⅴ〉配方Ⅲ〉配方Ⅱ〉配方Ⅳ〉配方Ⅰ,配方Ⅴ的效果最佳,有效率和治愈率分别达100％、88．9％。综合比较,本试验药物的治疗效果要优于传统药物。     

An Epidemiological Study of Foot Rot in Pastured Cattle

Using 12 years of data from the common grazing areas at Store Vildmose on the incidence of foot rot in cattle, it was shown that the disease incidence varied significantly between the sections in which the animals were grazing. Differences also existed between breeds in their foot rot incidence. Extraordinarily wet summers were noted to influence foot rot in cattle, and a possible effect of soil pH was also observed.Key words: foot rot, cattle, incidence, epidemiology, breed differences, climatic factors, lameness     

奶牛腐蹄病的分析与防治

对蚌埠蚂蚁山奶牛场奶牛腐蹄病发病情况进行了分析研究。结果表明,产奶牛1～≥6胎次腐蹄病的奶牛发病率分别为26．09％、27．64％、60．56％、68．09％、73．08％和81．25％,病蹄发病率分别是7．61％、8．13％、18．31％、23．40％、23．08％和23．44％,且3胎以上牛发病率明显大于1、2胎牛。就发病程度而言,1～5胎次间随着胎次的增加“中~ 、重”程度发病所占比例有逐渐加大的趋势,而“轻”程度发病呈现逐渐降低的变化;而6胎以上牛发病程度的变化与前者相反。     

Purification, characterization, and serologic characteristics of Bacteroides nodosus pili and use of a purified pili vaccine in sheep

Hair-like appendages (pili) were isolated and purified from Bacteroides nodosus, the etiologic agent of foot rot disease in sheep. Microscopic and biochemical analyses indicated that pili from organisms isolated in Australia, New Zealand, and the United States are morphologically and structurally similar. Pili are filamentous assemblies of identical protein subunits. Using specific antisera raised in rabbits against pili, 7 antigenic types were identified. A geographic pattern in the distribution of the pilus serotypes was not evident. In a preliminary vaccine trial, sheep vaccinated with purified pili developed resistance to challenge exposure to B nodosus. Protection was correlated positively with the serum anti-pilus antibody titers.     

Fusobacterium necrophorum and Bacteroides melaninogenicus as etiologic agents of foot rot in cattle.

Fusobacterium necrophorum (Sphaerophorus necrophorus) and Bacteroides melaninogenicus were the predominant bacteria isolated from biopsy specimens of lesions in cattle affected with foot rot. Mixed inoculums of the 2 bacteria, applied to the scarified interdigital skin or inoculated intradermally into the interdigital skin of test cattle, induced typical lesions of foot rot. Both bacteria were reisolated in large numbers from the induced lesions.     

Efficacy of amoxicillin trihydrate for the treatment of experimentally induced foot rot in cattle

Twenty holstein heifers were intradermally inoculated in the interdigital skin with a suspension containing Fusobacterium necrophorum and Bacteroides melaninogenicus to induce acute foot rot. Lesions, lameness, and swelling were evaluated during the study, using a subjective scoring system. Rectal temperature, species and number of bacteria isolated, and change in body weight were monitored throughout the study. Ten heifers (treated) were given amoxicillin trihydrate (10 mg/kg of body weight, IM) for 5 days, beginning at the onset of lameness. The remaining 10 heifers (controls) were given physiologic saline solution IM. Treated heifers had less severe lesions and greater weight gain than did control heifers. Rectal temperatures of treated heifers did not differ significantly from those of control heifers. It was concluded that administration of amoxicillin trihydrate early in the course of acute foot rot may reduce the severity of lesions associated with foot rot in cattle.     

Efficacy of ethylenediamine dihydriodide in the prevention of naturally occurring foot rot in cattle

The efficacy of an ethylenediamine dihydriodide containing salt mixture was evaluated with regard to the prevention of naturally occurring foot rot in pastured cattle. Ninety-six cattle were assigned to the treatment group and 96 were assigned to the control group. The groups were allowed consumption of salt-mineral mixtures, ad libitum, that were identical, except with respect to iodine concentration. The control group's mixture contained 0.0025% iodine and the treatment group's mixture contained 0.125% iodine (0.156% ethylenediamine dihydriodide). The incidence of foot rot was measured, as was the severity of the lesions and accompanying lameness. The incidence of foot rot in the control group (20.8%) was significantly (P less than 0.05) greater than the incidence in the treatment group (8.3%). The severity of foot rot was greater (P = 0.024) in the control calves vs the treatment calves. Total serum iodine concentrations were measured in the 2 groups on days 0, 46, and 130 of the experiment. The serum iodine values of the treatment group on day 46 (46 +/- 19.8 g/dl) and day 130 (23 +/- 12.3 g/dl) were significantly different (P less than 0.01) than the serum iodine concentrations of the control animals and the pretreatment values (day 0) of both groups. Production was measured via calf weaning weights. There were no detectable differences between the 205-day adjusted weaning weights of the calves in the control group vs the calves in the treatment group. Clinical signs of iodism were not observed in the cattle involved in this study.     

A comprehensive review of ceftiofur sodium and hydrochloride formulations for treatment of acute bovine foot rot

Seven well-controlled studies conducted under multiple management conditions demonstrated that ceftiofur, a late-generation veterinary parenteral cephalosporin, is effective for the treatment of bovine foot rot in beef and dairy cattle. Two preliminary dosage titration studies using a challenge model compared the efficacy of ceftiofur (1.1 mg or 2.2 mg ceftiofur equivalents [CE]/kg administered once daily for 3 days) with placebo. One preliminary clinical study evaluated the efficacy of ceftiofur sodium (1.0 mg CE/kg once daily for 3 days) in lactating dairy cows. Two clinical trials evaluated the efficacy of ceftiofur sodium versus placebo for naturally occurring foot rot, and two trials compared the efficacy of ceftiofur sodium or hydrochloride (1.0 mg CE/kg) with oxytetracycline (6.6 or 10 mg/kg), each administered once daily for 3 days, for treatment of acute foot rot in beef cattle. All trials demonstrated the efficacy of ceftiofur for treatment of acute bovine foot rot. Ceftiofur and oxytetracycline were comparable in efficacy, with ceftiofur having excellent injection-site tolerance and short or no milk discard or preslaughter withdrawal.     

牛用口蹄疫AsiaI—O型双价灭活苗与猪用口蹄疫O型灭活苗对猪的免疫效果比较试验

使用牛用口蹄疫AsiaI-O型双价灭活苗与猪用口蹄疫O型灭活苗分别接种50d商品猪和怀孕90d种猪,免疫前和免疫后的3w及7w进行抗体水平检测。O型口蹄疫采用正向间接血凝试验、AsiaI型口蹄疫采用液相阻断ELISA检测。同时对接种猪进行免疫应激观察。结果显示：猪使用牛用口蹄疫AsiaI—O型双价灭活苗3w后口蹄疫AsiaI的抗体水平十分低,最高只有5％,口蹄疫O型抗体合格率在35％以上;而注射猪用口蹄疫O型灭活苗的O型抗体水平合格率只有35％。而牛用口蹄疫AsiaI-O型双价灭活苗两次接种后,AsiaI和O型抗体水平均达到大于70％的要求。     

羊腐蹄病的诊治体会

羊腐蹄病主要是导致蹄部发生化脓、溃疡,出现跛行,呈现出发病率较高,感染性很快的特点。本文主要以一起羊腐蹄病的诊断与治疗为重点进行报告,较为详细地介绍了综合防治措施,旨在引导广大养殖者借鉴参考,做好该病的防治工作,减少养殖经济损失。