TABLE 1.
Summary of pig infection experiment
| No. of pigs infected | Challenge strain | Cumulative no. of pigs:
|
Clinical signs of surviving animal(s) (pig no.) | Mean ± SD of:
|
|||||
|---|---|---|---|---|---|---|---|---|---|
| Showing signs of diseasea at p.i. time
|
Euthanatized at p.i. time
|
||||||||
| 12 h | 15 h | 21 h | 44 h | Survival timeb (h) | Bacterial scorec | Pathological lesion scored | |||
| 5 | S7c | 2 | 3 | 3 | 3 | Subdued, mild lameness (1), Few signs (4) | 37.2 ± 9.4 | 4.2 ± 3.6 | 3.4 ± 2.6 |
| 5 | P1/7 | 1 | 5 | 4 | 4 | Subdued, mild lameness (9) | 35.3 ± 7.3 | 12.8 ± 6.8 | 9.6 ± 1.5 |
Marked lameness, shivering, vomiting, dullness, swollen joints, or dyspnea.
Survival times reflect the time taken for animals to reach predefined clinical end points. Three animals that did not reach these end points were assigned a time of 44 h. Differences between the two groups were not statistically significant.
Cumulative bacterial scores from each pig were obtained and the means were calculated per pig (maximum value, 24). Differences between the two groups were not statistically significant.
Pathological lesions in the peritonea, pleurae, pericardia, lungs, and joints were assessed by an experienced veterinary pathologist and were given scores from 0 (unaffected) to 3 (severely affected). For the joints, the highest value assigned was 4 (very severely affected). Differences between the two groups were statistically significant (P = 0.0018).