Efficacy of Medroxyprogesterone Acetate in Suppression of Estrus in Cycling Mares

Gee, Erica K.; DeLuca, Catherine; Stylski, J.L.; McCue, Patrick M.

doi:10.1016/j.jevs.2009.01.003

Cited by 15 publications

(7 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Suppressing reproductive function and associated oestrous behaviour in mares has been managed by several approaches. Pharmacological methods utilising progesterone or progestins and potentially reversible GnRH‐agonist or ‐antagonist therapy and their associated shortcomings including costs, practicality and potential negative side effects are reported [1–3]. Surgical ovariectomy is generally considered to be undesirable, due to its associated risks and irreversible loss of breeding potential [4].…”

Section: Introductionmentioning

confidence: 99%

Reversibility of the effects of GnRH‐vaccination used to suppress reproductive function in mares

Schulman

Botha

Muenscher

et al. 2012

Equine Veterinary Journal

View full text Add to dashboard Cite

SummaryReasons for performing study: Active immunisation against gonadotrophin-releasing hormone (GnRH) provides a reversible method for control of oestrous behaviour and fertility in mares. Previous reports failed to demonstrate the interval to resumption of cyclic ovarian activity after GnRH-vaccination. Hypothesis: Administration of the GnRH-vaccine Improvac in a large group of mares of various ages will result in effective, reliably reversible suppression of ovarian activity within a 2 year period. Methods: The mares, subdivided into 3 age categories, were vaccinated twice (with a 35 day interval) using 400 mg Improvac and monitored via blood samples until Day 720 after initial vaccination for serum progesterone concentration determination by radioimmune assay and anti-GnRH antibody titre by enzyme immunoassay. Samples were collected until individuals resumed cyclic ovarian activity. Results: All mares showed suppression of cyclic ovarian activity by clinical examination and serum progesterone concentration (SPC) Յ1 nmol/l by Day 70 and 92.2% resumed cyclic activity by SPC at Day 720 with a mean interval = 417.8 days (s.d. Ϯ 23.9; range 232-488 days, median 344 days). A significant age effect (P = 0.028) on the interval, but not on GnRH-antibody titre response, was observed between the youngest (Յ4 years) and oldest (Ն11 years) categories. Conclusions:Immunising adult mares of all ages with Improvac resulted in a reversible suppression of cyclic ovarian activity in most mares. An age effect, with the youngest mares showing a longer interval to reversibility, was observed.

show abstract

Section: Introductionmentioning

confidence: 99%

Reversibility of the effects of GnRH‐vaccination used to suppress reproductive function in mares

Schulman

Botha

Muenscher

et al. 2012

Equine Veterinary Journal

View full text Add to dashboard Cite

show abstract

“…The use of MPA in mares has occurred, but results and effectiveness vary. Gee et al, (2009) found that administration of compounded MPA starting on day 7 with 1,600 mg MPA intramuscularly and continuing with 400 mg on days 14, 21, 28, 35, and 42 had no effect on estrous behavior, nor follicular development, serum progesterone or LH concentrations.…”

Section: Medroxyprogesterone Acetatementioning

confidence: 91%

Effect of Chronic Administration of Oxytocin on Corpus Luteum Function in Cycling Mares

Parkinson

Vanderwall

Rigas

et al. 2020

Journal of Equine Veterinary Science

View full text Add to dashboard Cite

Undesirable and variable behavior in mares related to the estrous cycle is a common issue reported in the equine industry, especially for mares in a performance setting. These behaviors can interfere with, as well as decrease, overall performance.The objective of this study was to determine if administration of sixty units of oxytocin once daily for 29 days, regardless of when treatment was initiated during the estrous cycle, would induce prolonged corpus luteum (CL) function in cycling mares. Mares were randomly assigned to two groups: 1) saline-treated control (n=7) and 2) oxytocintreated (n=9). Control mares received 3 cc saline and oxytocin-treated mares received sixty units (3 cc) of oxytocin intramuscularly (IM) for 29 consecutive days. Treatment was initiated in all mares on the same day, independent of the day of the cycle. Jugular blood samples for determination of progesterone concentration were collected three times weekly (M, W, F) for 21 days before treatment was initiated. Beginning on the first day of treatment, blood samples were collected daily for seven days, three times weekly for iv the remainder of the treatment period, and then three times weekly for 45 days after the last treatment. Mares were considered to have prolonged CL function if serum progesterone remained >1.0 ng/mL for at least 30 days during/after the treatment period.The proportion of mares with prolonged CL function was higher in the oxytocin-treated group compared to the saline-treated group (7/9 vs. 1/7, respectively; P<0.05). Three of the seven oxytocin-treated mares that developed prolonged CL function initially underwent luteolysis within three to seven days of the start of oxytocin treatment, and then developed prolonged CL function following the subsequent ovulation during the treatment period. In the other four oxytocin-treated mares that developed prolonged CL function, progesterone remained >1.0 ng/mL throughout the treatment period and into the post-treatment period. All mares with prolonged CL function maintained elevated progesterone concentrations through at least day 56 of the study. Sixty units of exogenous oxytocin treatment for 29 consecutive days was effective in prolonging CL function as a means of estrus suppression in mares. (78 pages) v PUBLIC ABSTRACT Effect of Chronic Administration of Oxytocin on Corpus Luteum Function in Cycling Mares by Katherine Clissold Parkinson, Master of Science Utah State University, 2016 Undesirable and variable behavior in mares related to the reproductive cycle is a common issue reported in the equine industry, especially for female horses in a performance setting. These behaviors can interfere with and decrease, overall performance. The objective of this study was to determine if administration of 60 units of the hormone oxytocin once daily for 29 days, regardless of when treatment was initiated during the estrous cycle, would induce prolonged corpus luteum function in cycling mares. Mares were randomly assigned to two groups: 1) saline-treated control (n=7) and 2) oxytocin...

show abstract

“…Such a product (Readyserv 2 ) is currently licensed in Australia. The use of medroxyprogesterone acetate (MPA) has been shown to be ineffective in suppressing oestrus in mares [3,12,13]. Repeated injections with low dose intravenous [14] or high dose intramuscular [15] oxytocin prolongs dioestrus (thereby suppressing oestrus) in up to 70% of mares.…”

Section: Introductionmentioning

confidence: 99%

The effects of intrauterine infusion of peanut oil on endometrial health, salivary cortisol and interovulatory period in mares

et al. 2017

View full text Add to dashboard Cite

Efficacy of Medroxyprogesterone Acetate in Suppression of Estrus in Cycling Mares

Cited by 15 publications

References 21 publications

Reversibility of the effects of GnRH‐vaccination used to suppress reproductive function in mares

Reversibility of the effects of GnRH‐vaccination used to suppress reproductive function in mares

Effect of Chronic Administration of Oxytocin on Corpus Luteum Function in Cycling Mares

The effects of intrauterine infusion of peanut oil on endometrial health, salivary cortisol and interovulatory period in mares

Contact Info

Product

Resources

About