Pneumonic lesions in lambs in New Zealand: patterns of prevalence and effects on production

The role of Mycoplasma ovipneumoniae and Mycoplasma arginini in the respiratory mycoplasmosis of sheep and goats in Italy: Correlation of molecular data with histopathological features

Mycoplasma infections are commonly found in the respiratory system of small ruminants; the species most commonly detected are Mycoplasma ovipneumoniae and Mycoplasma arginini, associated with the so-called "atypical non-progressive pneumonia". The pathogenic role of M. ovipneumoniae in pneumonia has been demonstrated in sheep but still needs to be verified in goats; on the other hand, the role of M. arginini in sheep is not well understood, while in goats seems to be of low pathogenic value. The present study aims to investigate the aetiology of pneumonia in sheep and goats that died from respiratory disease using anatomopathological, histopathological, and molecular investigations and to clarify the role of respiratory mycoplasmas by the association of molecular data with histopathological features. First, to better understand which histological changes are actually suggestive of atypical pneumonia in sheep and goats, the study identified the histological lesions significantly associated with Mycoplasma spp. infection. Then, the histological score of lesions considered suggestive of atypical pneumonia was used to estimate the pathogenicity of each mycoplasma detected. The results showed that M. ovipneumoniae and M. arginini (alone or in mixed infections) are pathogenic both in sheep, as well as in goats with similar histology and severity of lesions. Moreover, young animals were statistically more susceptible to M.ovipneumoniae and M. arginini infection than adults. Animals appeared more at risk to the development of M. ovipneumoniae and M. arginini infection in summer.

Pharmacokinetic Behavior and Pharmacokinetic/Pharmacodynamic Integration of Danofloxacin Following Single or Co-Administration with Meloxicam in Healthy Lambs and Lambs with Respiratory Infections

The aim of this study was to determine the pharmacokinetics and pharmacodynamics of danofloxacin (DAN; 6 mg/kg) following subcutaneous administration alone or co-administration with meloxicam (MLX; 1 mg/kg) in healthy lambs and lambs with respiratory infections. The study was carried out using a total of four groups: HD (healthy; n = 6) and ID (infected; n = 7) groups who were administered DAN only, and HDM (healthy; n = 6) and IDM (infected; n = 7) groups who were administered DAN and MLX simultaneously. The plasma concentrations of DAN were determined using high-performance liquid chromatography–UV and analyzed by the non-compartmental method. DAN exhibited a similar elimination half-life in all groups, including both the healthy and infected lambs. The total clearance in the HDM, ID and IDM groups and volume of distribution in the HDM and IDM groups were significantly reduced. MLX in the IDM group significantly increased the area under the curve (AUC) and peak concentration (C_max) of DAN compared to the HD group. The Mannheimia haemolytica, Escherichia coli, and Streptococcus spp. strains were isolated from bronchoalveolar lavage fluid samples of the infected lambs. When co-administration with meloxicam, DAN at a 6 mg/kg dose can provide optimum values of ƒAUC_0–24/MIC (>56 h) and ƒC_max/MIC (>8) for susceptible M. haemolytica isolates with an MIC₉₀ value of 0.25 µg/mL and susceptible E. coli isolates with an MIC value of ≤0.125 µg/mL.

Quantifying disease and defect carcass losses at processing to improve feedback in the lamb supply chain: an arthritis case study

Context Lamb producers are currently limited in their ability to make informed on-farm management changes with respect to disease and defects identified at processing. This is due to the limited accuracy and detail of information included in disease and defect feedback supplied by processors. Increasing transparency of the feedback can allow producers to make more informed on-farm decisions, and, subsequently, improve productivity and animal welfare. Aims Using arthritis as a case study, the aim was to develop a scoring system that estimates hot standard carcass weight (HSCW) losses due to trimming at processing, so as to improve feedback to lamb producers. Methods An observational cross-sectional study was conducted at a southern New South Wales commercial processing facility, over 6 months and in five week-long blocks, from 21 February 2019 to 5 July 2019. Carcass trim components removed due to the presence of arthritis (shank or leg) were recorded for 217 of the 42164 lamb carcasses processed. Utilising average lot HSCWs, the total proportion of HSCW lost due to arthritis trimming (TPL) was calculated for each arthritic carcass. Linear regression analysis, with a logit-transform of TPL, was fitted to the data. Key results Processing lot and trim-component category were found to be significant (P << 0.001) explanatory variables for variation in TPL. Trim-component categories that were not significantly (P > 0.05) different were combined, with final categories being assigned arthritis trim scores as follows: 1, any forequarter shank; 2, any hindquarter shank; 3, any forequarter leg; and 4, any hindquarter leg. At an over-the-hooks carcass price of AU$7.83/kg and an average HSCW of 23.13 kg, these scores were used to estimate producer revenue losses per carcass (range AU$2.95–AU$18.08). Conclusions The accuracy and detail of information provided as feedback to lamb producers can be improved. For arthritis, this can be achieved using a trim-scoring system. Implications Altering feedback to include HSCW losses for processed lots in both kilograms and dollars against the associated disease or defect will better equip producers to make cost-effective on-farm management changes and reduce the impact on the lamb supply chain.

Impacts of major health conditions affecting the Australian sheepmeat value chain: a review

Major health conditions in sheep contribute to substantial economic losses throughout the sheepmeat supply chain in Australia. A systematic review was undertaken to explore the measurable impact of six conditions: arthritis, sheep measles, pleurisy, pneumonia, grass seeds and rib fractures, on the production of lamb and mutton across the meat value chain. Peer-reviewed scientific literature from three databases and non-peer-reviewed articles and reports from Australian government and non-government websites were searched between 11 and 17 November 2019. Original articles, including studies conducted in Australia and New Zealand, that had measurable impacts on conditions of interest were included. The search yielded 16 articles and reports and were classified as producer impact and/or processor impact studies. Mortalities were quantified for pneumonia and arthritis, with pneumonia having the highest impact for producers. Grass seed infestation resulted in the highest impact on carcase and liveweight losses compared to arthritis and pneumonia. Arthritis had the highest trim weight losses for both lamb and mutton and the highest rate of carcase condemnation. Grass seed was the only condition where other impacts on the processor (chain speed and staff relocation to the boning room) were quantified. Although quantifiable production and processing losses were available for some conditions, this review has highlighted that limited quantifiable data based on scientifically sound research were not available for other conditions. The evidence for some conditions found in this review can be used to target future research activities and to further assist producers in making informed management decisions on prevention and control.

Histological and immunohistochemical assessments of pneumonia in sheep slaughtered at Ibadan, Nigeria and Kumasi, Ghana

There is a decline in sheep production and contribution to the economy. This study described the histological pattern, immunohistochemically demonstrate bacterial and viral agents of pneumonia in sheep slaughtered in metropolitan abattoirs in Nigeria and Ghana. A total of 805 (600 in Ghana and 205 in Nigeria) sheep lungs were examined for pneumonic lesions. Sections were fixed in 10% formalin for histological and immunohistochemical analysis. Pneumonia of 8.7% was in Ghana and 13.3% in Nigeria. The histological findings included bronchopneumonia (16/70), broncho-interstitial pneumonia (9/70), interstitial pneumonia (9/70) and proliferative pneumonia (7/70). Ten (14.3%) cases were positive for PPRV, PI3V, and RSV antigens while five (7.2%) were positive for multiple viral antigens; including two (PI3V and PPRV), two (RSV and PPRV), and one (PI3V and RSV). RSV was in interstitial pneumonia, PPRV and PI3V were in interstitial and broncho-interstitial pneumonia. PPRV and PI3V antigens 3 (4.4%) were in proliferative alveolitis. Mannheimia haemolytica (2) and Pasteurella multocida (2) infection were in combination with PPRV, RSV, and PI3V. Three sheep lungs (4.4%) were negative for viruses and bacteria. This study revealed ovine pneumonia is still a problem in West Africa, and multivalent vaccine incorporating some of these agents will be useful for the control.

A pilot study of the effects of Mycoplasma ovipneumoniae exposure on domestic lamb growth and performance

Mycoplasma ovipneumoniae is a globally distributed pathogen that has been associated with pneumonia in both domestic and wild Caprinae. It is closely related to M. hyopneumoniae, a respiratory pathogen of swine that is associated with decreased growth rates of pigs as well as clinical respiratory disease. In order to assess the effects of M. ovipneumoniae on lamb performance, we generated a cohort of lambs free of M. ovipneumoniae by segregation of test negative ewes after lambing, then compared the growth and carcass quality traits of M. ovipneumoniae-free and -colonized lambs from weaning to harvest. Some signs of respiratory disease were observed during the feeding trial in both lamb groups, but the M. ovipneumoniae-exposed group included more affected lambs and higher average disease scores. At harvest, lungs of lambs in both groups showed few grossly visible lesions, although the M. ovipneumoniae-exposed group did exhibit increased microscopic lung lesions (P<0.05). In addition, M. ovipneumoniae exposed lambs produced lower average daily gains (P<0.05), and lower yield grade carcasses (P<0.05) compared to those of non-exposed lambs. The results demonstrated the feasibility of test and segregation for elimination of M. ovipneumoniae from groups of sheep and suggested that this pathogen may impair lamb growth and productivity even in the absence of overt respiratory disease.

Genome-wide association study of lung lesions and pleurisy in New Zealand lambs

Pneumonia is an important issue for sheep production, leading to reduced growth rate and a predisposition to pleurisy. The objective of this study was to identify loci associated with pneumonic lesions and pleurisy in New Zealand progeny test lambs. The lungs from 3,572 progeny-test lambs were scored for presence and severity of pneumonic lesions and pleurisy at slaughter. Animals were genotyped using the Illumina Ovine Infinium HD SNP BeadChip (606,006 markers). The heritability of lung lesion score and pleurisy were calculated using the genomic relationship matrix, and genome-wide association analyses were conducted using EMMAX and haplotype trend regression. At slaughter, 35% of lambs had pneumonic lesions, with 9% showing lesions on more than half of any individual lobe. The number of lambs recorded as having pleurisy by the processing plants was 9%. Heritability estimates for pneumonic lesions and pleurisy scores adjusted for heteroscedasticity (CPSa and PLEURa) were 0.16 (± 0.03) and 0.05 (± 0.02), respectively. Five single-nucleotide polymorphisms (SNPs) were significantly associated with pneumonic lesions at the genome-wide level, and additional 37 SNPs were suggestively significant. Four SNPs were significantly associated with pleurisy, with an additional 11 SNPs reaching the suggestive level of significance. There were no regions that overlapped between the 2 traits. Multiple SNPs were in regions that contained genes involved in either the DNA damage response or the innate immune response, including several that had previously been reported to have associations with respiratory disease. Both EMMAX and HTR analyses of pleurisy data showed a significant peak on chromosome 2, located downstream from the transcription factor SP3. SP3 activates or suppresses the expression of numerous genes, including several genes with known functions in the immune system. This study identified several SNPs associated with genes involved in both the innate immune response and the response to DNA damage that are associated with pneumonic lesions and pleurisy in lambs at slaughter. Additionally, the identification in sheep of several SNPs within genes that have previously been associated with the respiratory system in cattle, pigs, rats, and mice indicates that there may be common pathways that underlie the response to invasion by respiratory pathogens in multiple species.

Bronchopneumonia in Swedish lambs: a study of pathological changes and bacteriological agents

Background

One of the most common post-mortem inspection finding of sheep and lambs in Sweden, following routine slaughter is pneumonia and its prevalence is increasing. To our knowledge, the aetiology of pneumonia in lambs is not well-known for Swedish conditions. Chronic bronchopneumonia, also known as “atypical” or chronic non-progressive pneumonia, is a common disease worldwide, affecting lambs up to 12 months old. It is therefore of interest to elucidate if this disease complex is also a common cause of pneumonia among Swedish lambs. Chronic bronchopneumonia has a characteristic macroscopic and histopathologic appearance, and Mycoplasma ovipneumoniae is the microbial agent most frequently found. Although this bacterium is important for the pathogenesis, multiple agents are presumed to be involved. The aim of this study was to describe the macroscopic and histopathologic lung lesions in routinely slaughtered lambs with pneumonia, and to determine the bacterial agents involved.

Results

A total of 41 lungs with gross lesions consistent with pneumonia were examined. Of these, 35 lungs displayed the typical gross appearance of chronic bronchopneumonia, with several or all of the characteristic histological features. M. ovipneumoniae was detected in 83% of the 35 lungs and Mannheimia haemolytica was isolated in 71%. Pneumonia associated with M. ovipneumoniae could be correlated to specific gross lesions consistent with the gross description of chronic bronchopneumonia in lambs.

Conclusion

In this study, chronic bronchopneumonia was the most common lung disease in routinely slaughtered Swedish lambs. This diagnosis was based on the characteristic macroscopic and histopathologic pulmonary findings and the frequent presence of the bacterium M. ovipneumoniae. The macroscopic appearance of chronic bronchopneumonia could therefore be used during routine investigation of the lamb carcasses at slaughter, to determine the most likely cause of pneumonia.

Advances in diagnosis of respiratory diseases of small ruminants

Irrespective of aetiology, infectious respiratory diseases of sheep and goats contribute to 5.6 percent of the total diseases of small ruminants. These infectious respiratory disorders are divided into two groups: the diseases of upper respiratory tract, namely, nasal myiasis and enzootic nasal tumors, and diseases of lower respiratory tract, namely, peste des petits ruminants (PPR), parainfluenza, Pasteurellosis, Ovine progressive pneumonia, mycoplasmosis, caprine arthritis encephalitis virus, caseous lymphadenitis, verminous pneumonia, and many others. Depending upon aetiology, many of them are acute and fatal in nature. Early, rapid, and specific diagnosis of such diseases holds great importance to reduce the losses. The advanced enzyme-linked immunosorbent assays (ELISAs) for the detection of antigen as well as antibodies directly from the samples and molecular diagnostic assays along with microsatellites comprehensively assist in diagnosis as well as treatment and epidemiological studies. The present review discusses the advancements made in the diagnosis of common infectious respiratory diseases of sheep and goats. It would update the knowledge and help in adapting and implementing appropriate, timely, and confirmatory diagnostic procedures. Moreover, it would assist in designing appropriate prevention protocols and devising suitable control strategies to overcome respiratory diseases and alleviate the economic losses.

Isolation and antibiotic sensitivity of Streptococcus pneumoniae infections with involvement of multiple organs in lambs

Respiratory diseases particularly lamb pneumonia is a multifactorial disease involving the interaction between host, etiological agent and environment. The present study was carried out to determine the causative agent of an outbreak of pneumonia in a sheep flock and to establish its pathogenicity and public health importance. The incidence occurred in sheep unit at Madhurikund farm of University (DUVASU), Mathura, Uttar Pradesh, India. At the time of incidence, the population of sheep at the farm was 90. Affected animals were clinically examined and nasal swabs and blood samples were collected from live animals, while morbid materials were collected from dead animals after postmortem examination. The etiological agent was isolated and characterized with conventional microbiological and biochemical methods. Streptococcus pneumoniae was the bacteria isolated from blood, different organs and cerebrospinal fluid. The antibiotic sensitivity revealed resistant to multiple drugs viz., penicillin, tetracycline, erythromycin, chloramphenicol, enrofloxacin and ciprofloxacin. Pathological examination revealed multiple involvements of organs with different degrees of inflammation and haemorrhages of the lower respiratory tract, lungs, liver, heart and kidney. Further, its pathogenicity was established by histopathological examination. In conclusion, presence of multi drug resistant Streptococcus pneumoniae in weaning lambs with the involvement of multiple organs appears to be an emerging zoonotic threat to human particularly in shepherds. This seems to be the first report of isolation of multi drug resistant Streptococcus pneumoniae from outbreak in lambs with multiple organ involvement in India.

Treatment and control of respiratory disease in sheep

Respiratory diseases in sheep result in poor live weight gain and mortality, thus causing considerable financial losses for lamb producers. The disease is also an important animal welfare concern. Respiratory diseases in sheep and goats often result from adverse weather conditions and physiologic stress combined with viral and bacterial infections. It is essential to critically assess clinical diagnostic methods, treatment options, and control measures for the common respiratory diseases affecting sheep.

Economic effect of pneumonia and pleurisy in lambs in New Zealand

AIM

To estimate the cost of pneumonia and pleurisy in lambs to the sheep industry in New Zealand, in order to provide a reference for future cost-benefit calculations for control programmes to reduce the incidence of pneumonia.

METHODS

An estimate of the economic cost of pneumonia and pleurisy in lambs was based on: cohort studies of the association between growth rate and the extent of pneumonic lesions at slaughter (n=14 flocks), the prevalence of moderate to severe (MS) pneumonia (> or =10% lung surface area affected) and pleurisy (n=1,719 flocks), the correlation between the prevalence of MS pneumonia and economic loss at the flock level, and data on annual slaughter statistics and carcass value in New Zealand. A stochastic spreadsheet model was developed and run with 1,000 iterations. Input variables represented by probability distributions were growth rate, average cost of loss according to the prevalence of pneumonia per month, carcass value, prevalence of pleurisy, and carcasses downgraded for pleurisy, and annual national slaughter statistics. The output was a posterior distribution of the annual cost of disease.

RESULTS

The cost of pneumonia only included the loss associated with reduced growth rate, while mortality due to pneumonia was assumed to be low and was ignored. The cost of pleurisy included the loss associated with downgraded or condemned carcasses. Thus, the simulated annual average cost of pneumonia was NZ$28.1 (95% CI=NZ$15.0-42.0) million, and that of pleurisy NZ$25.1 (95% CI=NZ$10.2-48.1) million. The combined cost of pneumonia and pleurisy averaged NZ$53.2 (95% CI=NZ$32.4-78.9) million. The parameters with the greatest impact on the combined cost of pneumonia and pleurisy were prevalence of pleurisy between March and May, and cost of reduced growth due to pneumonia for lambs slaughtered in June.

CONCLUSIONS

The average cost of pneumonia and pleurisy to the sheep industry in New Zealand due to reduced lamb growth and decreased carcass value is likely to be between NZ$32.4 and $78.9 million. This is a conservative estimate, omitting mortalities, indicating that pneumonia and pleurisy have substantial economic impact on sheep farming in New Zealand. Considering that 23,833,000 lambs were slaughtered in 2003/2004 (average value $65.56/lamb), this cost would equate to NZ$1.36-3.31 per lamb.

CLINICAL RELEVANCE

Pneumonia and pleurisy are common diseases in lambs in New Zealand, leading to substantial economic loss to producers.

Hierarchical and spatial analyses of pneumonia-lesion prevalence at slaughter in New Zealand lambs

We recorded lesions of moderate-to-severe pneumonia (>or=10% lung surface area affected; "pneumonia") in 1,899,556 lambs submitted to three New Zealand abbatoirs between December 2000 and September 2001. The average prevalence of pneumonia ranged between 7 and 13%, by abbatoir. We ran a two-level mixed-effects binomial logistic-regression model with the prevalence of pneumonia as the outcome, and adjusting for abbatoir and month. The intracluster correlations for batch (slaughter lambs from the same farm sent at the same time) and farm were 31.3 and 12.4%, respectively. (We also noted threefold differences in odds across abbatoirs, and >30-fold differences among slaughter months.) Case flocks (those in the upper quintile of pneumonia prevalence) generally were not clustered in the spatial incidence-risk analysis (after adjusting for flock-level and batch level effects, and as compared to flocks in the lower two quintiles). We therefore concluded that the risk of moderate-to-severe pneumonia-lesion prevalence detectable at slaughter of lambs was determined at the flock and batch level, rather than at the spatial level.