Ultrasound Knowledge About Equine Pregnancy

Ultrasound Knowledge About Equine Pregnancy 

Karestar Technology (Xuzhou) Co., Ltd

(Figure1)

1. 马的发情周期平均为 21 天(包括发情期(estrus)和间情期 (diestrus)), 受季节、光照和个体差异影响，周期可能缩短至 16 天或延长至 25 天. 马的发情期通常是 5-7 天,排卵通常发生在发 情即将结束时,发情期 5-7 后,马在配种之前可以先用超声测试卵 泡的直径,大概 35 毫米以上，更好受孕. 

1.The average estrus cycle in horses is 21 days (including estrus and diestrus). Depending on season, light exposure, and individualvariation, the cycle can be shortened to 16 days or extended to 25 days. The estrus period in horses is typically 5-7 days, with ovulation typically occurring near the end of estrus. After 5-7 days of estrus, ultrasound can be used to measure the diameter of the ovarian follicles before breeding. A diameter of 35 mm or larger is recommended for optimal conception.

备注:对于生殖道超声检查，母马必须被适当地限制在马鞍中或 手持站立，其后端靠在马厩门口。大多数母马都能很好地忍受这 一过程，尽管偶尔可能需要抽动鼻子或使用化学药物。适当的约 束不仅对于执行手术的兽医的安全很重要，而且还可以确保不会 对母马的直肠造成伤害。理想情况下，应包裹尾巴以避免尾毛插 入直肠。在扫描子宫之前，将装有润滑的一次性塑料套管的手臂 放置在直肠内，仔细清除粪便。如果小心执行，这不是一个危险 的过程，谨慎的触诊，B 超机不会伤害早期胚胎或胎儿。

For a reproductive tract ultrasound, the mare must be properly restrained in a saddle or handheld standing with her rear end against the stall door. Most mares tolerate this procedure well, although occasional snout twitching or the application of chemicals may be necessary. Proper restraint is important not only for the safety of the veterinarian performing the procedure but also to ensure that no injury occurs to the mare's rectum. Ideally, the tail should be wrapped to prevent insertion of tail hair into the rectum. Before scanning the uterus, an arm equipped with a lubricated, disposable plastic cannula is placed in the rectum and carefully cleared of feces. If performed with care, this is not a dangerous procedure; careful palpation and ultrasound will not harm the early embryo or fetus.

2. 母马配种后最早可在 10 天左右使用马用 B 超进行妊娠诊断， 不过这个时期还是以小囊泡的形式出现，经验不足很容易跟卵泡 混淆，所以我们不建议这个时期对马进行 B 超孕检。这个时期的 囊泡直径大约 3-4mm（图 2），在 B 超屏幕上能看到一个小黑洞。

2.Equine ultrasound can be used to diagnose pregnancy as early as 10 days after mating. However, during this period, the pregnancy appears as small follicles, which can be easily confused with ovarian follicles if inexperienced. Therefore, ultrasound is not recommended for pregnancy testing in horses during this period. The follicles at this stage are approximately 3-4 mm in diameter(Figure 2), and appear as small black holes on the ultrasound screen.

(Figure 2)

3. 理想情况下，为了确认怀孕，应在配种后 16 至 18 天之间进 行检查。此时，胚胎固定在子宫角底部，并且看起来是具有高回 声边缘的圆形低回声结构。这也是识别和消除双胎妊娠的理想时 机。应在妊娠 1 个月左右进行一次额外检查以确认怀孕，因为 大多数妊娠都会在此窗口期终止。历史上曾受孕失败的高危母马 可能需要更频繁的超声波检查来跟踪和监测妊娠情况。这些检查 应进一步通过血液检查来补充，以检查黄体酮水平，并在承保之 前进行繁殖健全性检查，包括子宫培养和细胞学、超声波和可能 的活检。未婚母马也可能从更频繁的观察中受益。10-17 天囊泡平均每天增加约 3-4 毫米，这个时候还不能看到胚胎本身，一直 以囊泡形态显示，B 超图像显示只是黑洞体积变大一些（图 3） 

3.High-risk mares with a history of conception failure may require more frequent ultrasounds to track and monitor pregnancy. These examinations should be supplemented with blood tests to check progesterone levels and a reproductive health check, including uterine culture and cytology, ultrasound, and possibly a biopsy, performed prior to underwriting. Unmarried mares may also benefit from more frequent observations. From day 310 to day 17, the cyst grows by an average of 3-4 mm per day. At this stage, the embryo itself cannot be seen and continues to appear as a cyst. Ultrasound images show that only the black hole has grown in size (Figure 3).

(Figure 3)

4. 21-23 天的时候，就能看到胚胎本体了，B 超图像中表现为囊泡边缘的小不规则性，最常见的是朝向腹侧（底部）区域（图 4）。 

4.Between 21 and 23 days, the embryo proper can be seen, appearing on ultrasound images as small irregularities at the edge of the vesicle, most commonly toward the ventral (bottom) region (Figure 4).

(Figure 4)

5. 33 天时尿囊已经增大并且胚胎背侧（向上）升高，而卵黄囊 几乎完全退化 

5.By day 33, the allantois has enlarged and the embryo is elevated dorsally (upward), while the yolk sac has almost completely degenerated(Figure 5)

(Figure 5)

6. 43 天时，发育中的小马驹的术语将从“胚胎”变为“胎儿”， 以部分认识到随着脐部形成，营养来源的状态发生了变化，尿囊 绒毛膜开始附着在子宫内膜上，成为胎盘-该过程直到怀孕 140 天左右才完成。在不久的将来，胎儿的大小将使其无法在母马超 声妊娠图像中完全可见。 

6.At 43 days, the terminology for the developing foal will change from "embryo" to "fetus" to partially recognize the change in nutritional status as the umbilicus forms and the chorioallantoic membrane begins to attach to the uterine lining to become the placenta—a process that is not complete until around 140 days of gestation. In the near future, the size of the fetus will prevent it from being fully visible on ultrasound images of the mare's pregnancy(Figure 6)

(Figure 6)

备注: 大多数母马流产发生在怀孕的前 45 天内。因此，在此阶 段对母马进行监测非常重要，以防在同一季节内进行再繁殖。初 次确定妊娠后，至少在 21 至 25 天左右重新检查母马，然后在排 卵后 30 和 60 天再次检查。异常妊娠、双胎减少以及之前流产的 母马可能需要更频繁地检查。 

Note: Most mare miscarriages occur within the first 45 days of pregnancy. Therefore, it is important to monitor mares during this period to prevent rebreeding within the same season. After initial confirmation of pregnancy, reexamine the mare at least 21 to 25 days after ovulation and again 30 and 60 days after ovulation. Abnormal pregnancies, reduced twins, and mares with previous miscarriages may require more frequent examinations.