The blood body formed just after ovulation in horses and donkeys is a blood body. The veterinary B-ultrasound image shows no echo in the middle, a dark area, and a reticular structure with strong echoes. The newly formed corpus luteum is highly echogenic, some with low echo areas in the middle, and some with low echo areas around. The corpus luteum tissue of cattle is weakly reflected on the veterinary B-ultrasound image, and has a clear boundary with the ovarian stroma with slightly stronger reflections around it. The structure of the corpus luteum is different at different stages. The echo of the red body formed after ovulation is weaker than that of the mature corpus luteum, and the mature corpus luteum is easy to distinguish with a depression. Usually, the central echo of the corpus luteum is stronger. The corpus luteum on the 8th to 10th day of the estrus cycle often has a circular liquid dark area in its center, but as the corpus luteum develops further, the dark area gradually shrinks and even disappears. The functional corpus luteum of the general estrus cycle is about 20 mm in diameter. The pregnant corpus luteum is slightly larger than the cyclical corpus luteum. It appears on the 19th day of the estrus cycle (before estrus), and the cyclical corpus luteum begins to degenerate, and the boundary with the ovarian stroma becomes blurred. Kito et al. studied the relationship between corpora lutea with cavity, i.e. cystic corpora lutea and infertility, and found that 37.2% of corpora lutea had cavity, of which 24.4% had cavity diameter of 10 mm, and 30.8% had diameter of 7 mm and above, but most of them shrank or disappeared after 10 days, and no relationship with infertility was found.

The first detection rate of corpora lutea in young cows was: 73% on the first day of ovulation, 16% on the second day, and 11% on the third to fifth day, and the subsequent detection rate was the same as that on the second day. It also pointed out that the corpora lutea with regular edges can be found by ultrasound in cattle 3 days after ovulation. The sensitivity of bovine corpora lutea to the direct inspection method and veterinary B-ultrasound method for the two methods was 83.3% and 80.6%. Townson et al. used veterinary B-ultrasound to find that about 50% of the horse corpus luteum can produce consistent echoes throughout the detection period (the echo-free central cavity inside only occupies 10% of the cross-section of the corpus luteum); the remaining 50% of the corpus luteum forms an echo-free blood clot area in the center.