Impact of Strain Variation of Dichelobacter nodosus on Disease Severity and Presence in Sheep Flocks in England

AprV2 and aprB2 are variants of the apr gene of Dichelobacter nodosus, the cause of footrot in sheep. They are putative markers for severe and mild disease expression. The aim of our study was to investigate the distribution of aprV2 and aprB2 in flocks with and without footrot. Our hypotheses were that both strains are present in endemically affected flocks, with aprB2 and aprV2 associated with mild and virulent phenotypes respectively but that D. nodosus is not present in flocks without footrot. Alternatively, aprB2 persists in flocks without footrot. Despite extensive searching over 3 years only three flocks of sheep without footrot were identified. D. nodosus was not detected in these three flocks. In one further flock, only mild interdigital dermatitis was observed, and only aprB2 was detected. Twenty-four flocks with endemic footrot of all severities were sampled on three occasions and all were positive for D. nodosus and the aprV2 variant; aprB2 was detected in only 11 of these flocks. AprB2 was detected as a co-infection with aprV2 in the 22% of samples positive for aprB2 and was more likely in mild footrot phenotypes than severe. Dichelobacter nodosus serogroups were not associated with footrot phenotype. We conclude that D. nodosus, even aprB2 strains, do not persist in flocks in the absence of footrot. Our results support the hypothesis that aprB2 is associated with mild footrot phenotypes. Finally, we conclude that given the small number of flocks without footrot that were identified, footrot is highly endemic in English sheep flocks.

The dysbiosis of ovine foot microbiome during the development and treatment of contagious ovine digital dermatitis

Background Contagious Ovine Digital Dermatitis (CODD) is an emerging and common infectious foot disease of sheep which causes severe welfare and economic problems for the sheep industry. The aetiology of the disease is not fully understood and control of the disease is problematic. The aim of this study was to investigate the polybacterial aetiopathogenesis of CODD and the effects of antibiotic treatment, in a longitudinal study of an experimentally induced disease outbreak using a 16S rRNA gene amplicon sequencing approach. Results CODD was induced in 15/30 experimental sheep. During the development of CODD three distinct phenotypic lesion stages were observed. These were an initial interdigital dermatitis (ID) lesion, followed by a footrot (FR) lesion, then finally a CODD lesion. Distinct microbiota were observed for each lesion in terms of microbial diversity, clustering and composition. Porphyromonadaceae, Family XI, Veillonellaceae and Fusobacteriaceae were significantly associated with the diseased feet. Veillonellaceae and Fusobacteriaceae were most associated with the earlier stages of ID and footrot rather than CODD. Following antibiotic treatment of the sheep, the foot microbiota showed a strong tendency to return to the composition of the healthy state. The microbiota composition of CODD lesions collected by swab and biopsy methods were different. In particular, the Spirochaetaceae family were more abundant in samples collected by the biopsy method, suggesting that these bacteria are present in deeper tissues of the diseased foot. Conclusion In this study, CODD presented as part of a spectrum of poly-bacterial foot disease strongly associated with bacterial families Porphyromonadaceae, Family XI (a family in Clostridiales also known as Clostridium cluster XI), Veillonellaceae and Fusobacteriaceae which are predominately Gram-negative anaerobes. Following antibiotic treatment, the microbiome showed a strong tendency to return to the composition of the healthy state. The composition of the healthy foot microbiome does not influence susceptibility to CODD. Based on the data presented here and that CODD appears to be the severest end stage of sheep infectious foot disease lesions, better control of the initial ID and FR lesions would enable better control of CODD and enable better animal welfare.

An appraisal study of donkey in three Northern states of Nigeria

This qualitative study on donkey was conducted in Bauchi, Kano and Kebbi States of Nigeria. The objective of the study was to understand the role, significance and potential areas needing intervention in donkey rearing in the rural setting. The study was also used to obtain first-hand baseline information on the state of knowledge on the donkey in the states surveyed. Sixty two locations were visited comprising 36 from Kebbi, 19 from Bauchi and 17 from Kano States respectively. Rapid Rural Participatory Appraisal (RRPA) technique with check list of questions and farmers' participation was employed in villages/towns randomly selected to cover all the ecological zones in each of the three States. A meeting of one to two hours was organized with the farmers and donkey owners. Observations were made on donkeys at home and in the field. Problems mentioned by respondents included: Colics (Anomari),ulcerative lymphangitis, inflammation of the tongue, interdigital dermatitis, ear sore, fistulous withers, unknown causes of lameness and nervous system disorder called locally as "chinkai chinkai". There were generally poor or no veterinary facilities and services in most of the villages and towns. It was not the farmers practice to take donkeys to clinic for treatment. Mortality was high during the late dry season in most places but also occurred in the rainy season in some places. Areas for further investigations were also highlighted.

PSV-13 Incidence of infectious and non-infectious feet lesions and their association with carcass quality in sheep at a slaughter plant in Alberta

Infectious and non-infectious feet lesions (FL) in livestock have been associated with reduced welfare, production, carcass and meat quality. Currently, the incidence of FL in sheep and its relationship with carcass quality has not been documented in Canada. The objectives of this study were to determine 1) the incidence and type of lesions in Alberta sheep at slaughter and 2) the relationship between FL and carcass quality. A total of 4,487 sheep carcasses were assessed for FL at a slaughter plant in Alberta, Canada between October 2017 and March 2019. Approximately 300 sheep were evaluated monthly by two experienced observers who recorded common infectious (IN) and non-infectious (NIN) lesions. In addition, carcass information including hot carcass weight (HCW), and back fat thickness (BFT) were obtained from the slaughter plant records. Data were analyzed by multivariable regression models using SAS PROC GLIMMIX. Overall, FL incidence was 9.4% (7.0% having one lesion and 2.4% having more than one lesion). Infectious lesions accounted for 45.7% of all lesions [footrot (37.1%), interdigital dermatitis (7.3%), and contagious ecthyma (1.3%)], while NIN lesions accounted for 54.3% [overgrown horn (21.9%), injury (13.6%), laminitis (10.2%), and other lesions (8.6%)]. Sheep with IN had lower BFT (13.5 ± 1.32 cm, P = 0.0002) and HCW (51.5 ± 1.89 kg, P = 0.0189) than NIN (15.8 ± 1.51 cm and 54.7 ± 1.97 kg, respectively). For every 1 cm decrease in BFT and 1 kg decrease in HCW the odds of IN increased by 0.89 (P < 0.0001) and 0.98 (P = 0.0229), respectively. Based on our findings, foot lesions are a significant issue for the Canadian sheep industry and infectious lesions may have greater detrimental effect on carcass quality than non-infectious lesions. Further studies are necessary to understand the relationship of carcass quality and feet lesion.

The Dysbiosis of Ovine Foot Microbiome During the Development and Treatment of Contagious Ovine Digital Dermatitis

Background: Contagious Ovine Digital Dermatitis (CODD) is an emerging and common infectious foot disease of sheep which causes severe welfare and economic problems for the sheep industry. The aetiology of the disease is not fully understood and control of the disease is problematic. The aim of this study was to investigate the polybacterial aetiopathogenesis of CODD and the effects of antibiotic treatment, in a longitudinal study of an experimentally induced disease outbreak using a 16S rRNA gene amplicon sequencing approach.Results: CODD was induced in 15/30 experimental sheep. During the development of CODD three distinct phenotypic lesion stages were observed. These were an initial interdigital dermatitis (ID) lesion, followed by a footrot (FR) lesion, then finally a CODD lesion. Distinct microbiota were observed for each lesion in terms of microbial diversity, clustering and composition. Porphyromonadaceae, Familiy XI, Veillonellaceae and Fusobacteriaceae were significantly associated with the diseased feet. Veillonellaceae and Fusobacteriaceae were most associated with the earlier stages of ID and footrot rather than CODD. Following antibiotic treatment of the sheep, the foot microbiota showed a strong tendency to return to the composition of the healthy state. The microbiota composition of CODD lesions collected by swab and biopsy methods were different. In particular, the Spirochaetaceae family were more abundant in samples collected by the biopsy method, suggesting that these bacteria are present in deeper tissues of the diseased foot. Conclusion: In this study, CODD presented as part of a spectrum of poly-bacterial foot disease strongly associated with bacterial families Porphyromonadaceae, Family XI (a family in Clostridiales also known as Clostridium cluster XI), Veillonellaceae and Fusobacteriaceae which are predominately Gram-negative anaerobes. Following antibiotic treatment, the microbiome showed a strong tendency to return to the composition of the healthy state. The composition of the healthy foot microbiome does not influence susceptibility to CODD. Based on the data presented here and that CODD appears to be the severest end stage of sheep infectious foot disease lesions, better control of the initial ID and FR lesions would enable better control of CODD and enable better animal welfare.

Genomic heterogeneity of Dichelobacter nodosus within and between UK sheep flocks and between age groups within a flock

Background Footrot and interdigital dermatitis are endemic infectious diseases in all sheep farming regions, impairing welfare and production. The development of efficacious vaccines against the primary causative pathogen has been hampered by the extensive antigenic diversity of Dichelobacter nodosus . Understanding the heterogeneity of the pathogen within and between flocks is essential if the feasibility of bespoke vaccine production is to be assessed for use in the U.K. Results In this study 56 ewe and lamb isolates from 9 flocks were compared by D. nodosus serogroup and Multi Locus Sequence Type which provides significantly enhanced discriminatory power for molecular epidemiology. Serogroup heterogeneity between flocks ranged from two to five unique serogroups per flock. Three flocks contained isolates of two serogroups, two flocks contained isolates of three serogroups and one flock included isolates of five serogroups. Analysis of 25 isolates from one flock with high prevalence of lameness, identified that serogroup and sequence type was significantly correlated with age. Significantly higher proportion of lambs were infected with serogroup B (principally ST85) as opposed to serogroup H (principally ST86), which predominated amongst adult sheep. Conclusions Genomic heterogeneity of the pathogen was significantly lower within flock compared to heterogenicity observed between flocks. Furthermore, this study indicates that within a flock, the host-pathogen dynamics and susceptibility to particular D. nodosus strains may be age dependent. Keywords D. nodosus; Footrot; interdigital dermatitis; lameness; sheep; MLST; Serogroup; molecular epidemiology

Genomic heterogeneity of Dichelobacter nodosus within and between UK sheep flocks and between age groups within a flock

Footrot and interdigital dermatitis are endemic infectious diseases in all sheep farming regions, impairing welfare and production. The development of efficacious vaccines against the primary causative pathogen has been hampered by the extensive antigenic diversity of Dichelobacter nodosus . Understanding the heterogeneity of the pathogen within and between farms is essential if the feasibility of bespoke vaccine production is to be assessed for use in the U.K. In this study 56 ewe and lamb isolates from 9 farms were compared by D. nodosus serogroup and Multi Locus Sequence Type which provides significantly enhanced discriminatory power for molecular epidemiology. Within farm genomic heterogeneity was significantly lower than between farms. Serogroup heterogeneity between flocks ranged from two to five unique serogroups per flock. Three flocks contained isolates of two serogroups, two flocks contained isolates of three serogroups and one flock included isolates of five serogroups. Analysis of 25 isolates from one flock with high prevalence of lameness, identified that serogroup and sequence type was significantly correlated with age. Significantly higher proportion of lambs were infected with serogroup B (principally ST85) as opposed to serogroup H (principally ST86), which predominated amongst adult sheep. This indicates that host-pathogen dynamics and susceptibility to particular D. nodosus strains may be age dependent.

Genomic heterogeneity of Dichelobacter nodosus within and between UK sheep flocks and between age groups within a flock

Footrot and interdigital dermatitis are endemic infectious diseases in all sheep farming regions, impairing welfare and production. The development of efficacious vaccines against the primary causative pathogen has been hampered by the extensive antigenic diversity of Dichelobacter nodosus. Understanding the heterogeneity of the pathogen within and between farms is essential if the feasibility of bespoke vaccine production is to be assessed. In this study 56 ewe and lamb isolates from 9 farms were compared by D. nodosus serogroup and Multi Locus Sequence Type which provides significantly enhanced discriminatory power for molecular epidemiology. . Within farm genomic heterogeneity was significantly lower than between farms. Serogroup heterogeneity between flocks ranged from two to five unique serogroups per flock. Three flocks contained isolates of two serogroups, two flocks contained isolates of three serogroups and one flock included isolates of five serogroups. Analysis of 25 isolates from one flock with high prevalence of lameness, identified that serogroup and sequence type was significantly correlated with age. Significantly higher proportion of lambs were infected with serogroup B (principally ST85) as opposed to serogroup H (principally ST86), which predominated amongst adult sheep. This indicates that host-pathogen dynamics and susceptibility to particular D. nodosus strains may be age dependent.

Assessment of Oxidative Status in Foot Diseases of Sheep

Background: Oxidative stress plays an important role in the etiology and/or progression of various diseases in the livestock. The aim of this study was to investigate the relationship between foot diseases and oxidant and antioxidant levels, determining catalase (CAT) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA), nitric oxide (NO) and glutathione (GSH) concentrations in sheep with foot disease such as interdigital dermatitis, footrot and interdigital pouch infection (biflex canal inflammation).Materials, Methods & Results: In the study, a total of 70 sheep aged between 1 and 3, 20 sheep with interdigital dermatitis, 20 with foot-rot, 10 with interdigital pouch inflammation and 20 clinically healthy Akkaraman sheep, were used. The blood samples collected from the V. Jugularis of the sheep were centrifuged and their serums were obtained. MDA and NO levels of the sheep with interdigital dermatitis, footrot and interdigital pouch infection were found to be significantly higher than those of animals in the control group (P < 0.001). CAT activity was determined to be significantly lower in all diseased animals than in the animals in the control group (P < 0.001). GSH-Px and GSH levels were significantly lower in the animals with interdigital dermatitis than in the control group (respectively P < 0.001, P < 0.05).Discussion: Oxidative stress regulates the metabolic activity of some organs and plays an important role in productivity in livestock. The oxidative stress is reported that caused by the increase in the production of excessive free radicals resulting from the exposure of animals to various stress factors and by the weakening of the antioxidant defense has an important role in the pathogenesis of numerous diseases such as foot diseases. In the presence of various stress factors, the level of malondialdehyde (MDA) and nitric oxide (NO) increases. MDA is determine the degree of cellular damage in tissues. Nitric oxide is produced in large quantities by macrophages in case of bacterial infections and exhibits antibacterial properties against pathogenic microorganisms. For this reason, NO is very high levels in inflammatory diseases. Catalase (CAT), glutathione peroxidase (GSH-Px), and glutathione (GSH) is some of the important antioxidants and play an important role in the oxidative defense of tissues. In this study, the increase in serum MDA and NO levels was mostly found in interdigital dermatitis cases, then in footrot cases and finally in interdigital pouch infection cases. Serum CAT levels were found to be significantly lower than that of the control group (P < 0.001). In this study, the highest decrease in serum CAT levels was detected in interdigital dermatitis cases and followed by footrot cases and interdigital pouch infection cases, respectively. Serum GSH-Px and GSH levels were found to be significantly lower in interdigital dermatitis cases than those in the control group (respectively P < 0.001, P < 0.05). There was no statistically significant difference found between the serum GSH-Px and GSH levels of footrot and interdigital pouch infection cases, and the control group (P > 0.05). We found that serum MDA and NO levels were found to significantly increase in sheep with foot disease and serum CAT levels were found to be significantly lower. The results of this research indicate that MDA, NO and CAT activities may be more reliable parameters than GSH-Px and GSH activities in order to determine oxidative stress in sheep with foot diseases. In conclusion, this study reveals that there is a relationship between foot diseases and oxidant/antioxidant balance in sheep and it shows that the oxidative stress and lipid peroxidation develop due to the increase of free radicals.