Changes in intrauterine pressure after oxytocin administration in reproductively normal mares and in those with a delay in uterine clearance.
Abstract: Intrauterine pressure was measured in 4 reproductively normal mares and 4 mares with delay in uterine clearance after administration of oxytocin to determine if intrauterine pressure varied between dosage and group. Changes in intrauterine pressure were measured during estrus, when a follicle was > or =35 mm, using a Millar "Mikro-tip" catheter that had 3 discrete pressure sensors/channels. Mares received 4 different treatments of 10, 5, 2.5 or 0 IU (vehicle) of oxytocin. The protocol for each treatment consisted of a 10-min baseline recording, administration of treatment and measurement of changes in intrauterine pressure for 65 min. After administration of the first two treatments, mares were rested for 2 h and the protocol repeated for the remaining 2 treatments. Changes in intrauterine pressure were measured on a physiograph and stored in a computer. The results were analyzed by 4x4 Latin Square Design analysis of variance (ANOVA) using the GLM procedure of the Statistical Analysis System. The ANOVA detected a main effect of treatment (P<0.01) and mare (nested within group; P<0.01) but no effect of channels, group or treatment-by-group interaction. There was a dose-dependent increase in uterine activity in both normal mares and those with delayed uterine clearance. A dose of 10 IU of oxytocin induced a larger number of uterine contractions (5.67+/-0.06) for a longer time (24.09+/-1.18 min) than the 5 IU (4.16+/-0.06 contractions and 16.31+/-1.18; P<0.01 min) or 2.5 IU dose (4.08+/-0.06 contractions and 17.61+/-1.18 min). The first intrauterine wave occurred most often near the tip of the horn in 10 of 12 recordings in normal mares and in 8 of 12 recordings in mares with delayed uterine clearance. It was then propagated from the middle of the horn to the uterine body just cranial to the cervix. There was no pattern of propagation for subsequent intrauterine pressure waves. We conclude that the difference in spontaneous clearance of the uterus between the 2 groups is not reflected in their response to exogenous oxytocin as determined by changes in intrauterine pressure.
Publication Date: 2000-03-23 PubMed ID: 10729023DOI: 10.1016/s0093-691x(99)00047-3Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research studied the effect of oxytocin on the intrauterine pressure in horses, both in normal conditions and in those with delays in uterus clearance. Observations showed a dose-dependent increase in uterine activity and found no difference in response to oxytocin between the two groups.
Research Objective
- The objective was to determine whether intrauterine pressure differed between varying doses and groups after the administration of oxytocin. This research was intended to provide insights into the intrauterine reactions in reproductively normal mares versus those with delays in uterus clearance, a common fertility issue among horses.
Methodology
- The study involved eight mares, four of which were reproductively normal and four with delayed uterine clearance. The intrauterine pressure changes in these two groups were measured using a special catheter after four different oxytocin treatment doses.
- Each treatment followed a protocol of a 10-minute baseline recording, administration of the treatment, and post-treatment intrauterine pressure measurement for 65 minutes.
- After the initial oxytocin doses, the mares underwent a 2-hour resting period before the protocol was repeated for the remaining doses.
Findings
- There was a noticeable dose-dependent increase in uterine activity in both normal mares and those with a delay in uterus clearance. Higher doses induced more uterine contractions for a longer time duration.
- The intrauterine wave often initiated near the tip of the horn and propagated towards the middle. However, there was no distinct pattern on subsequent intrauterine pressure waves.
- Despite the difference in spontaneous uterus clearance between the two groups, the response to exogenous oxytocin, as reflected by changes in intrauterine pressure, did not vary.
Conclusion
- The researchers concluded that any natural differences in uterus clearance time do not impact how mares, either healthy or with delayed uterine clearance, respond to externally administered oxytocin. Therefore, oxytocin usage doesn’t seem to be significantly influenced by the reproductive health of the mare in terms of causing changes in intrauterine pressure.
Cite This Article
APA
Cadario ME, Merritt AM, Archbald LF, Thatcher WW, LeBlanc MM.
(2000).
Changes in intrauterine pressure after oxytocin administration in reproductively normal mares and in those with a delay in uterine clearance.
Theriogenology, 51(5), 1017-1025.
https://doi.org/10.1016/s0093-691x(99)00047-3 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences, University of Florida, Gainesville 32610, USA.
MeSH Terms
- Animals
- Estrus / physiology
- Female
- Horses / physiology
- Oxytocin / pharmacology
- Oxytocin / physiology
- Pressure
- Restraint, Physical / veterinary
- Transducers, Pressure / veterinary
- Ultrasonography
- Uterine Contraction / drug effects
- Uterine Contraction / physiology
- Uterus / diagnostic imaging
- Uterus / drug effects
- Uterus / physiology
Citations
This article has been cited 5 times.- Scarlet D, Malama E, Fischer S, Knutti B, Bollwein H. Relationship between Clinical Uterine Findings, Therapy, and Fertility in the Mare.. Vet Sci 2023 Mar 29;10(4).
- Diel de Amorim M, Klein C, Foster R, Dong L, Lopez-Rodriguez MF, Card C. Expression of Oxytocin/Neurophysin I and Oxytocinase in the Equine Conceptus from Day 8 to Day 21 Post-Ovulation.. Animals (Basel) 2022 Mar 22;12(7).
- Karam KM, Alebady AS, Alhilfi HO, Al-Delemi DH. Comparative study utilizing different post-breeding treatment regimens in cyclic Arabian mares.. Vet World 2021 Nov;14(11):2863-2868.
- Lange-Consiglio A, Funghi F, Cantile C, Idda A, Cremonesi F, Riccaboni P. Case Report: Use of Amniotic Microvesicles for Regenerative Medicine Treatment of a Mare With Chronic Endometritis.. Front Vet Sci 2020;7:347.
- Maischberger E, Irwin J, Carrington S, Duggan V. Equine post-breeding endometritis: A review.. Ir Vet J 2008 Mar 1;61(3):163-8.
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