Study of agglutinins to Brucella abortus, B canis and Actinobacillus equuli in horses.

This study investigated the presence of antibodies for Brucella abortus, B canis, and Actinobacillus equuli in horses. It was found that some of the horses in a veterinary hospital and a slaughterhouse have these specific antibodies, with various results showing a link to age, but not sex.

Research Methodology

• Researchers collected samples from horses in two different locations – a veterinary teaching hospital and a slaughterhouse.
• They looked for the presence of antibodies to three specific bacteria: Brucella abortus, B canis, and Actinobacillus equuli.
• They used techniques including a card test and a tube agglutination test to examine antibody levels, and also used 2-mercaptoethanol serum treatment to try and reduce high antibody levels.
• They also carried out culture tests to confirm the presence of bacteria.

Findings

• Out of 141 hospitalised horses, four had a titre (concentration of antibodies in blood) of 1:100 or greater to Brucella abortus. However, none of the 73 slaughtered horses showed this level of antibodies.
• Six horses from both populations reacted to the card test, and one was culture positive, indicating the presence of bacteria.
• Using a card test with B canis antigen, 38% of the serum samples from hospitalised horses and all of the slaughtered horses showed a positive result. 27.4% of the latter group had high titres in a tube agglutination test.
• Importantly, high titres could not be reduced by 2-mercaptoethanol serum treatment, indicating a strong immune response.
• It was noticed that high titres appeared to be associated with advanced age but not with the sex of the horse.
• Lastly, when researchers used B canis to adsorb (bind) the sera, it did not affect the titres to Actinobacillus equuli. However, when they did the reverse (using A equuli to adsorb the sera), the titre levels to B canis were affected – suggesting a cross-reactivity between the antigens of these two types of bacteria.