A comparison of Freund’s Complete and Freund’s Modified Adjuvants used with a contraceptive vaccine in wild horses (Equus caballus).

The research investigated the use of two different adjuvants in a contraceptive vaccine used for wild horses, and found that Freund’s Modified Adjuvant worked just as effectively as Freund’s Complete Adjuvant.

Study Design and Process

• The study involved fifteen captive wild mares that were treated with a contraceptive vaccine and either Freund’s Complete Adjuvant (7 mares) or Freund’s Modified Adjuvant (8 mares).
• All of the mares received a booster inoculation of the contraceptive, along with Freund’s Incomplete Adjuvant, one month after initial treatment.

Measurement and Analysis

• The researchers measured the levels of anti-porcine zona pellucida antibodies in the mares over a ten-month period following the initial inoculation.
• Their analysis showed that there were no significant differences in these antibody levels at any point during this period, regardless of which adjuvant had been used.

Results and Conclusion

• At the end of the study, seven out of the eight mares in the Freund’s Modified Adjuvant group had antibody levels above the 60% threshold, which is considered to be the contraceptive threshold for horses.
• There were no significant differences in antibody levels between pregnant and non-pregnant horses, and age also didn’t appear to have any impact on antibody levels.
• Only one adverse reaction was observed after the booster treatment, and 11 healthy foals were born during the course of the study, indicating that the vaccines were safe for use in the mares.
• The results suggest that Freund’s Modified Adjuvant can be used as a substitute for Freund’s Complete Adjuvant in both captive and free-ranging wildlife.