Evaluation of the ability of altrenogest to control the equine estrous cycle.
Abstract: In our experience, altrenogest has not always been able to exert predictable control over the estrous cycle of the mare. Therefore, we examined 12 mares that were treated with altrenogest to identify reasons for its failure to control the estrous cycle. The mares were fed altrenogest for 15 to 20 days and were examined for follicle development, ovulation, and corpus luteum formation during treatment. Through the use of real-time ultrasonography and radioimmunoassay for progesterone, we concluded that altrenogest was unable to suppress the growth of follicles to preovulatory size in some mares, leading to ovulation during treatment or earlier than expected after the end of treatment. In addition, altrenogest did not appear to shorten the life-spans of the corpora lutea that were formed during treatment; in 4 mares, this resulted in the persistence of corpora lutea after the end of the suggested 15-day periods of treatment. The latter findings led us to suggest that if a luteolytic dose of prostaglandin had been given at the end of altrenogest treatment, there would have been improved control over the estrous cycle. The results of our study confirmed our clinical impressions that altrenogest may be satisfactory to control the equine estrous cycle under some circumstances, but it should not be used when precise control over ovulation is required.
Publication Date: 1989-02-01 PubMed ID: 2645256
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- Journal Article
Summary
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This research paper studies the effectiveness of altrenogest, a hormonal treatment, in regulating the equine estrous cycle (reproductive cycle in horses). The study details their observation that the treatment is sometimes inefficient, prompting the researchers to explore the causes of its inability to accurately maintain control of the cycle.
Research Methodology
- The researchers used a sample of 12 mares treated with altrenogest.
- Each of these mares was given altrenogest for a period of between 15 to 20 days.
- The researchers closely monitored each mare, particularly observing follicle development, ovulation, and formation of the corpus luteum during the treatment period.
- They utilized real-time ultrasonography and performed radioimmunoassay tests (a technique used to measure concentration of hormones in the blood) for progesterone to aid their real-time tracking.
Findings
- The study found that altrenogest did not consistently suppress the growth of follicles to a preovulatory size resulting in some mares ovulating during treatment or earlier than expected, post-treatment.
- Altrenogest also did not appear to affect the lifespans of corpora lutea (plural of corpus luteum) that formed during the treatment. For 4 out of 12 mares observed, these corpora lutea persisted beyond the end of the 15-day treatment period.
- This led the researchers to hypothesize that if a luteolytic dose (a dose that causes regression of the corpus luteum) of prostaglandin had been administered at the end of the altrenogest treatment, it would have been able to better control the estrous cycle.
Conclusion
- The findings from this study showed that altrenogest could be satisfactory in controlling the equine estrous cycle under certain conditions. However, it is not reliable where precise control over ovulation time is needed.
- By implicating the use of a luteolytic dose of prostaglandin, researchers suggest a potential approach to address the inadequacies of altrenogest as a hormonal regulator of the equine estrous cycle.
Cite This Article
APA
Lofstedt RM, Patel JH.
(1989).
Evaluation of the ability of altrenogest to control the equine estrous cycle.
J Am Vet Med Assoc, 194(3), 361-364.
Publication
Researcher Affiliations
- Department of Medicine, School of Veterinary Medicine, Tufts University, North Grafton, MA 01536.
MeSH Terms
- Animals
- Corpus Luteum / drug effects
- Corpus Luteum / physiology
- Estrenes / pharmacology
- Estrus / drug effects
- Female
- Horses / physiology
- Ovarian Follicle / drug effects
- Ovarian Follicle / physiology
- Ovulation / drug effects
- Progesterone / blood
- Progesterone Congeners / pharmacology
- Radioimmunoassay
- Trenbolone Acetate / analogs & derivatives
- Trenbolone Acetate / pharmacology
- Ultrasonography / veterinary
Citations
This article has been cited 4 times.- Straticò P, Hattab J, Guerri G, Carluccio A, Bandera L, Celani G, Marruchella G, Varasano V, Petrizzi L. Behavioral Disorders in Mares with Ovarian Disorders, Outcome after Laparoscopic Ovariectomy: A Case Series.. Vet Sci 2023 Jul 25;10(8).
- Aurich C, Kaps M. Suppression of reproductive behaviour and gonadal function in female horses-An update.. Reprod Domest Anim 2022 Sep;57 Suppl 4(Suppl 4):4-12.
- Stewart RA, Pelican KM, Crosier AE, Pukazhenthi BS, Wildt DE, Ottinger MA, Howard J. Oral progestin priming increases ovarian sensitivity to gonadotropin stimulation and improves luteal function in the cat.. Biol Reprod 2012 Jun;87(6):137.
- Stewart RA, Pelican KM, Brown JL, Wildt DE, Ottinger MA, Howard JG. Oral progestin induces rapid, reversible suppression of ovarian activity in the cat.. Gen Comp Endocrinol 2010 Apr 1;166(2):409-16.
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