Plasma haptoglobin concentration in swine after challenge with Streptococcus suis.

Eight 15-week-old pigs, reared under specific pathogen-free conditions, were inoculated with Streptococcus suis serotype 2. The animals were monitored before and after challenge by measuring rectal temperature, recording specific clinical symptoms and collecting blood samples for haptoglobin determination. Twenty-four hours after infection, the average haptoglobin plasma concentration of the animal group increased significantly and reached a maximum 4 days post-inoculation, followed by a constant mean level until the end of the trial on day 10. In spite of individual differences between the animals, an increase in haptoglobin concentration of at least 2.5 times above normal was observed in all infected pigs 1 day after challenge. Twenty-four hours after challenge, lameness was observed in five animals and an elevated body temperature was observed in seven of the eight experimental infected animals. These are the classical clinical symptoms of streptococcal infection. Haptoglobin was shown to increase in acute S. suis infection in pigs.