Trimester of Abortion Caused by Trichomonas foetus in Cattle

Trichomonas foetus causes abortion in cattle during which trimester of pregnancy?

Correct Answer: 1st trimester

Tritrichomonas foetus (a protozoan parasite) causes abortion in cattle specifically during the first trimester of pregnancy (first 3 months / approximately first 90 days).

Trichomoniasis in Cattle — Key Facts

• It is a venereal disease — transmitted during coitus from infected bull to cow.
• The organism colonizes the cervix and uterus, causing post-coital pyometra (uterus fills with a 'potato soup-like' pus).
• Infection leads to early embryonic death and first-trimester abortion — hence repeat breeding is a common presentation.
• Bulls are asymptomatic carriers; the organism lives in the penile sheath and prepuce.

Comparison of Trimester of Abortion by Pathogen

• 1st trimester: Tritrichomonas foetus ✔
• Last trimester: Brucella abortus, Leptospira, Listeria, Mycobacterium

Why Other Options Are Wrong

• 2nd/3rd trimester → T. foetus primarily kills the embryo early; by the 2nd trimester the infection may lead to pyometra rather than abortion per se.