Effects of estrous cycle and season on ultrasonic uterine anatomy in mares.
Abstract: The morphological changes in ultrasound images of the uterus at various times of the year were characterized in nonbred mares, using a linear-array scanner. The uterus was recorded as having an ultrasonic morphology characteristic of diestrus (uterine score 1, endometrial folds not visible), estrus (score 3, distinct endometrial folds), or an intermediate stage (score 2). In Experiment I, uterine scores for the first ovulatory period of the year were compared to scores for the second period in 23 pony mares. More mares (P<0.05) showed endometrial folding prior to the second ovulation of the year (14 23 ) than prior to the first (5 23 ). Mean uterine scores were higher (P<0.05) on Day -10 (ovulation = Day 0) and tended to be higher (P<0.1) on Days -14, -13, and -11 of the first ovulatory period than on the corresponding days of the second period. Uterine scores for the first ovulatory period were lower (P<0.05) on Days -5, -4, -3, -2, -1, and 0 and tended to be lower (P<0.01) on Day -6. In addition, the pattern of change in uterine scores paralleled the pattern of change in the intensity of estrous behavior. In Experiment II, in 20 horse mares, the curve for uterine scores during interovulatory intervals in May-June, but not in September-October, was bimodal due to a small rise (P<0.05) and subsequent return to baseline between Days +3 and +6. The mean uterine scores for both May-June and September-October began to increase on Day -7 or -8, reached maximum on Day -3, declined between Days -2 and 0, continued to decline after Day 0, and reached a value characteristic of diestrus by Day +2. Results indicated that the ultrasonic characteristics of the uterus may provide an instant indicator of estrogen exposure and may have practical value in judging the optimal time to breed.
Publication Date: 1985-10-01 PubMed ID: 16726101DOI: 10.1016/0093-691x(85)90053-6Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The paper examines the changes in ultrasound images of a mare’s uterus at different times of the year to understand its relationship with estrus cycles and seasons.
Study Overview
- The research mainly aimed to explore the morphological changes in the ultrasound images of the uterus in nonbred mares during different times of the year. The ultrasonic characteristics were recorded as usually seen in diestrus (an intermediate stage between successive periodic cycles), estrus (the period of sexual receptivity), or an intermediate stage.
Experiment I
- In the first experiment, the study participants were 23 pony mares. Their uterine scores for the first ovulatory period of the year were compared with those of the second period.
- It was found out that more mares demonstrated endometrial folding (the folding of the inner layer of the uterus) prior to the second ovulation rather than the first one in the year.
- The mean uterine scores showed variations depending on the days related to the ovulation days for the two ovulatory periods of the year. On certain days prior to ovulation during the first ovulatory period, higher scores were observed when compared with the same pre-ovulation days of the second period.
- Moreover, during the first ovulatory period, lower uterine scores were reported closer to and on the day of ovulation, suggesting fluctuations in uterine conditions depending on the stage of the ovulatory period.
- The pattern of changes in uterine scores appears to mirror the pattern of changes in estrous behavior, implying a linkage between the two.
Experiment II
- The second experiment involved 20 horse mares. The uterine scores during the periods between two ovulations (interovulatory intervals) in May-June and September-October were examined.
- Unlike in September-October, a bimodal curve for uterine scores was observed in May-June, attributed to a minor rise and subsequent return to normal levels between the days following ovulation.
- The mean uterine scores for both these periods began to rise about a week before ovulation, peaked three days prior to ovulation, declined until the day of ovulation, and continued to decrease post-ovulation, finally reaching values typical of diestrus two days after ovulation.
Implications of the Study
- The findings suggest that the ultrasound characteristics of the uterus could serve as an immediate indicator of estrogen exposure in mares.
- These features also appear to have potential practical applications in determining the best time to breed mares, indicating direct benefits for equine reproduction management.
Cite This Article
APA
Hayes KE, Pierson RA, Scraba ST, Ginther OJ.
(1985).
Effects of estrous cycle and season on ultrasonic uterine anatomy in mares.
Theriogenology, 24(4), 465-477.
https://doi.org/10.1016/0093-691x(85)90053-6 Publication
Researcher Affiliations
- Department of Veterinary Science University of Wisconsin-Madison Madison, WI 53706 USA.
Citations
This article has been cited 5 times.- Madhavan MK, DeMayo FJ, Lydon JP, Joshi NR, Fazleabas AT, Arora R. Aberrant uterine folding in mice disrupts implantation chamber formation and alignment of embryo-uterine axes. Development 2022 Jun 1;149(11).
- Rosa LC, Dias ECS, Melo RS, do Rosário CJRM, Pereira FLC, Chung LBO, da Anunciação ARA, Moraes FJ, Souza FA, Chaves RM. The ovarian and uterine responses of Baixadeiro mares to prostaglandin synchronization during the dry and rainy seasons. Anim Reprod 2022;19(1):e20200050.
- Sugiura T, Akiyoshi S, Inoue F, Yanagawa Y, Moriyoshi M, Tajima M, Katagiri S. Relationship between bovine endometrial thickness and plasma progesterone and estradiol concentrations in natural and induced estrus. J Reprod Dev 2018 Apr 13;64(2):135-143.
- Gharagozlou F, Akbarinejad V, Youssefi R, Masoudifard M, Hasani N. Reduced anti-Müllerian hormone (AMH) in mares with hemorrhagic anovulatory follicles. Iran J Vet Res 2014 Fall;15(4):336-40.
- Vecchi I, Sabbioni A, Bigliardi E, Morini G, Ferrari L, Di Ciommo F, Superchi P, Parmigiani E. Relationship between body fat and body condition score and their effects on estrous cycles of the Standardbred maiden mare. Vet Res Commun 2010 Jun;34 Suppl 1:S41-5.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
