Causative Agent of Post-Coital Pyometra in Cattle

Post-coital pyometra in cattle is caused by:

Correct Answer: Trichomonas (Tritrichomonas foetus)

Post-coital pyometra in cattle (accumulation of pus in the uterus after mating) is caused by Tritrichomonas foetus, a protozoan parasite transmitted venereally during coitus.

Pathogenesis of Trichomoniasis

• The protozoan is carried asymptomatically by bulls (in the preputial cavity) and is transmitted to cows during natural mating.
• In cows: vaginal discharge → cervicitis → endometritis → pyometra ('potato soup' appearance of pus) → maceration of foetus if pregnant
• Causes abortion in the 1st trimester of pregnancy
• Bulls are carriers but rarely show clinical signs

Why Not the Other Options?

• Leptospira: Causes abortion mainly in last trimester; not specifically post-coital pyometra
• Listeria: Causes abortion in last trimester; mainly a foodborne pathogen (silage disease)
• Campylobacter fetus: Causes early embryonic death and infertility, but characteristic feature is NOT pyometra; it is more associated with irregular estrus cycles and low conception rates