Artificial infection of sheep with multiple strains of<i>Dichelobacter nodosus</i>to induce footrot

Allworth, Maxwell; Egerton, J. R.

doi:10.1111/avj.12612

Cited by 6 publications

(33 citation statements)

References 18 publications

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“…As reported in our previous study, Merinos were more severely affected by the serogroup A strain and Polwarths by the serogroup E and H strains, suggesting specific interactions between D. nodosus isolates and the breed of sheep.…”

Section: Discussionmentioning

confidence: 99%

“…Daily rainfall was recorded and temperature data were available from a weather station located 60 km from the property. Mean daily and monthly temperatures were calculated as previously described …”

Section: Methodsmentioning

confidence: 99%

“…A summary of the trial protocol is presented in Table . Footrot was introduced into the flock (−8 weeks, Table ), as previously described, via both footrot‐affected sheep and direct application of seven D. nodosus strains with varying serogroups (A–H) and virulence (one benign strain, five intermediate strains and the virulent strain, A198). All sheep were kept as a composite flock for 4 weeks following the introduction of footrot and then placed in their allocated paddocks (−4 weeks, Table ).…”

Section: Methodsmentioning

confidence: 99%

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Comparison of footbathing and vaccination to control ovine footrot in an experimentally infected flock

Allworth

Egerton

2018

Aust Veterinary J

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Objective Compare footbathing and vaccination for control of footrot during a transmission period in a sheep flock deliberately infected with multiple strains of Dichelobacter nodosus. Methods The strains included a known virulent strain, a benign strain and several intermediate strains. The resulting footrot was clinically intermediate. A total of 1450 Polwarth sheep aged 1–3 years were allocated to one of five treatment groups: untreated, weekly walkthrough zinc sulfate footbathing, 1‐hour stand‐in Footrite® footbathing every 3 weeks, vaccination with a commercial multivalent whole‐cell vaccine and vaccination with a novel recombinant DNA fimbrial vaccine. There were four replicates, in four paddocks. Results Of the untreated animals, 76% had footrot. Footbathing, either weekly or every 3 weeks, restricted the prevalence to 6/283 (2%; 97% effective) and 18/275 (6.5%; 91% effective), respectively. This was significantly lower than the prevalence in either the untreated or vaccinated group (P < 0.001). Weekly footbathing resulted in significantly fewer affected sheep than footbathing for 1 h every 3 weeks (P < 0.05). Vaccination with either whole‐cell or recombinant vaccines significantly (P < 0.001) reduced the prevalence ((142/280 (51%; 33% effective), 114/278 (41%; 46% effective) respectively), with the recombinant vaccine superior (P < 0.05) to whole‐cell vaccination. Significantly (P < 0.05) fewer 1‐year‐old sheep had footrot than older sheep. A single Footrite treatment reduced the prevalence to 12% (53/445) compared with a prevalence of 57% (27/47) for untreated sheep (79% effective). Conclusion In this study footbathing was more effective than vaccination at controlling and treating multistrain footrot.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Comparison of footbathing and vaccination to control ovine footrot in an experimentally infected flock

Allworth

Egerton

2018

Aust Veterinary J

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“…The strains of D. nodosus were selected from previously recovered isolates so that each strain was from a different serogroup and the strains represented a spectrum of virulence, including the well‐documented virulent A strain (CSIRO 198, VCS1001) (Supplementary table 1).…”

Section: Methodsmentioning

confidence: 99%

“…A large on‐farm study was set up to further investigate the elimination of different strains of D. nodosus. The successful establishment of a flock with multiple D. nodosus strains and the application of different control methods to this flock during the spring transmission period produced a flock that was likely to have both clinically affected and cured sheep in it. The success of an elimination program in this flock was evaluated and is described here.…”

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confidence: 99%

Relationship between the likelihood of footrot elimination from a flock and the virulence of the strain of Dichelobacter nodosus present

Allworth

Egerton

2018

Aust Veterinary J

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Objective To assess ability to eliminate different strains of footrot in sheep using inspection and culling of affected sheep. Methods A flock of 1417 Polwarth sheep that had deliberately been infected with seven different strains of Dichelobacter nodosus and undergone different control measures prior to eradication, including zinc sulfate footbathing and vaccination, were subjected to visual foot inspection on a number of occasions. Sheep identified as infected or having any foot abnormalities were removed from the flock at each inspection. The experiment had three replicates and a small number of untreated control animals. Sheep were examined following the inspections to assess the effectiveness of elimination and additional measures were implemented in two of the three replicates in an attempt to eliminate all strains of D. nodosus. Results Three strains of D. nodosus were apparently successfully eliminated from all replicates (strains A, E and H). Strains B and C were detected in one replicate each, despite additional inspections. The three stains that were eliminated were the more virulent strains and the two strains that remained were the least virulent. No assessment could be made on a further two strains. Conclusions The application of a rigorous inspection and culling program resulted in the elimination of the more virulent D. nodosus strains, but did not result in the elimination of all D. nodosus strains on all occasions.

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In this issue – August 2017

Jackson¹

2017

Aust Veterinary J

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Artificial infection of sheep with multiple strains ofDichelobacter nodosusto induce footrot

Abstract: The clinical expression of multiple-strain infections has implications for both research and control of footrot. A novel method of control is proposed.

Cited by 6 publications

References 18 publications

Comparison of footbathing and vaccination to control ovine footrot in an experimentally infected flock

Comparison of footbathing and vaccination to control ovine footrot in an experimentally infected flock

Relationship between the likelihood of footrot elimination from a flock and the virulence of the strain of Dichelobacter nodosus present

In this issue – August 2017

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