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Novel Respiratory Health Score for APp Infection

by 5m Editor
15 June 2009, at 8:47am

GERMANY - Dr Hoeltig and colleagues at the University of Veterinary Medicine in Hanover have tested a novel Respiratory Health Score (RHS) for Actinobacillus pleuropneumoniae (APp) infection. In a paper published in BMC Veterinary Research, they report a highly significant correlation between the new RHS in live pigs and the lung lesion score carried out post mortem, which is considered as the 'gold standard'.

Bacterial lung infections are a major cause of economic losses in the pig industry; they are responsible for approximately 50 per cent of the antibiotics used in pigs and, therefore, also present an increasing concern to consumer protection agencies. In response to this changing market, the authors investigated the feasibility of an old approach aimed at the breeding selection of more resistant pigs. As a first step in this direction we applied a new respiratory health score system to study the susceptibility of four different pig breeding lines (German Landrace, Pietrain, Hampshire and Large White) towards the respiratory tract pathogen Actinobacillus pleuropneumoniae (APp).

Results

A controlled experimental aerosol infection with an A. pleuropneumoniae serotype 7 isolate was performed using 106 weaning pigs of defined breeding lines from the breeds German Landrace, Pietrain, Hampshire and Large White.

Pigs were clinically assessed on days four and 20 post infection following a novel scoring system, the Respiratory Health Score (RHS), which combines clinical, sonographic and radiographic examination results.

The ranking on day 4 was significantly correlated with the ranking based on the pathomorphological Lung Lesion Score (LLS; Spearman Rank Correlation Coefficient of 0.86; p<0.0001).

Based on their RHS, pigs were assigned to the different quartiles independent of the breeding line. The RHS-based rankings of pigs on day 4 and on day 20 were highly correlated (Spearman Rank Correlation Coefficient of 0.82; p<0.0001) independent of the breeding line.

Pigs of the Hampshire line were predominantly found in the lowest scoring quartile (47.6 per cent) and absent in the highest scoring quartile. In contrast, pigs of the German Landrace and Pietrain breeding lines were predominantly found in the highest scoring quartile (32.3 per cent and 35.7 per cent, respectively).

Conclusion

These results demonstrate that the RHS obtained from live pigs shows a highly significant correlation to the lung lesion score considered as a 'gold standard'. The correlation of the ranking at days 4 and 20 post infection implies that the course of disease is highly dependent on the acute lung damage.

The different severity of signs between the tested pig breeding lines clearly suggests a genetic difference in the susceptibility of pigs to A. pleuropneumoniae infection.

Reference

Hoeltig D., I. Hennig-Pauka, K. Thies, T. Rehm, M. Beyerbach, K. Strutzberg-Minder, G.F. Gerlach, K-H. Waldmann and FUGATO-consortium IRAS. 2009. A novel Respiratory Health Score (RHS) supports a role of acute lung damage and pig breed in the course of an Actinobacillus pleuropneumoniae infection. BMC Veterinary Research 2009, 5:14. doi:10.1186/1746-6148-5-14

Further Reading

- You can view the full report by clicking here.
- Find out more information on Actinobacillus pleuropneumonia (APp) by clicking here.

5m Editor