Observations on the long term effects of Brucella abortus infection in the horse, including effects during pregnancy and lactation.

The research focuses on the long-term effects of infection by Brucella abortus in horses and its impacts during their pregnancy and lactation. The study found that horses were able to breed normally after such an infection, with no organisms recovered, and that the serum of one foal yielded maternal antibodies.

Objectives of the Study

• This research aims to explore the impact and long-term effects of Brucella abortus infection in horses, particularly during pregnancy and lactation periods.
• The study also considers the serum-antibody levels in horses post-infection and whether the infection impacts foaling.

Methodology Employed

• A group of horses, consisting of five mares and a stallion, were experimentally infected with Brucella abortus strain 544. The pattern of their health, breeding, and antibody levels were observed for a period ranging from three to 30 months.
• The researchers carried out various tests including the antiglobulin (Coombs) test, complement fixation tests, serum-antibody assessment, and intradermal tests.

Key Findings of the Research

• The study found that despite being infected with Brucella abortus, the mares were able to breed normally within the observed period.
• No organisms related to the bacteria were recovered either from the horses or from the pregnant Friesian heifer contacts, suggesting that the infection may not have propagated.
• Interestingly, the levels of serum antibody – as evaluated using the antiglobulin (Coombs) and complement fixation tests – fell slower than those measured via other techniques.
• From the one foal’s serum that was examined, maternal antibodies were discovered indicating a potential transfer of immunity from the mare to the foal.
• Additionally, the intradermal test gave a positive result only in infected adult horses, but was negative in all foals, providing potential indicators of infection status and age-related susceptibility.