Alteration in uterine contractility in mares with experimentally induced placentitis.
Abstract: An experimental model of ascending placentitis was developed in the mare to characterize the uterine myoelectrical pattern in late gestation and determine how ascending placentitis altered this pattern. In experiment 1, myometrial electrical activity was analyzed during the early morning, late morning and evening hours in four mares in the last 15 days of gestation to identify patterns of activity. In experiment 2, nine mares received intra-cervical inoculations of Streptococcus equi subspecies zooepidemicus. Myoelectrical activity in the early morning and evening hours in these mares was compared with four control mares. In experiment 1, the number of spike burst clusters >30 s was greater in the evening than in the late morning hours (P < 0.04). Spike burst activity (number x duration) of mares in experiment 1 was similar during day and night recordings until the last 6 days of gestation when it gradually increased each evening until parturition (P < 0.05). In experiment 2, control mares experienced a gradual increase in the number of small spike burst clusters in the last 6 days (P = 0.008) and an increase in large and small spike burst clusters in the evening hours in the last 4 days of gestation (P = 0.03). Mares with experimentally induced placentitis never exhibited a rise in spike burst clusters but had an increase in the mean duration and activity index of large spike burst clusters in the 4 days before parturition (P < 0.04). In conclusion, control mares had a progressive, reversible rise in myoelectrical activity at night in the week preceding parturition. This was not observed in mares with experimentally induced placentitis. They exhibited an increase in the intensity and duration of large spike burst clusters possibly in response to local inflammation.
Publication Date: 2004-04-02 PubMed ID: 15056770DOI: 10.1530/rep.1.00021Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research investigates how an experimentally induced infection of the placenta, or placentitis, in late-term pregnant mares changes their uterine electrical activity patterns. It further compares these patterns to control mares to understand the impact of placentitis on upcoming parturition.
Objective and Methodology
- The study’s primary aim was to design an experimental model of ascending placentitis in mares and observe how this condition affects the electrical activity in the uterus, particularly towards the end of gestation.
- Two main experiments were conducted. In the first experiment, researchers analyzed the electrical activity in the uteri of four mares during different periods of the day in the final 15 days of gestation.
- In the second experiment, nine mares were given intra-cervical inoculations of Streptococcus equi subspecies zooepidemicus, a bacterium known to cause equine placentitis, and their uterine electrical activity was compared to that of four control mares.
Findings from the First Experiment
- In the first experiment, it was found that the number of “spike burst clusters,” a measure of electrical activity, greater than 30 seconds was higher during the evening than in the late morning hours.
- The researchers also noted that the spike burst activity remained consistent during day and night until the last six days of gestation. During these final days, the activity gradually increased every evening until the mares gave birth.
Findings from the Second Experiment
- The second experiment’s control mares witnessed a gradual rise in the number of small spike burst clusters in the last six days.
- There was also an increase in both large and small spike burst clusters during the evening hours in the last four days of gestation.
- However, the mares with experimentally induced placentitis did not display a rise in spike burst clusters. Interestingly, these mares showed an increase in the mean duration and activity index of large spike burst clusters in the four days leading up to birth.
Conclusion
- Findings suggest that, in standard conditions, there is a progressive, reversible rise in uterine electrical activity at night in the week before parturition.
- This pattern was not observed in mares suffering from experimentally induced placentitis – instead of a rise in the number of spike burst clusters, they experienced an increase in the intensity and duration of the clusters.
- The variation in uterine electrical activity in mares with placentitis could be a response to the inflammation caused by the condition.
Cite This Article
APA
McGlothlin JA, Lester GD, Hansen PJ, Thomas M, Pablo L, Hawkins DL, LeBlanc MM.
(2004).
Alteration in uterine contractility in mares with experimentally induced placentitis.
Reproduction, 127(1), 57-66.
https://doi.org/10.1530/rep.1.00021 Publication
Researcher Affiliations
- Department of Large Animal Clinical Sciences and Department of Animal Sciences, University of Florida, Gainesville, Florida 32610, USA.
MeSH Terms
- Animals
- Electromyography
- Female
- Gestational Age
- Horse Diseases / physiopathology
- Horses
- Placenta Diseases / physiopathology
- Pregnancy
- Streptococcal Infections / physiopathology
- Uterine Contraction
Citations
This article has been cited 2 times.- Cummins C, Carrington S, Fitzpatrick E, Duggan V. Ascending placentitis in the mare: A review. Ir Vet J 2008 May 1;61(5):307-13.
- Morales-Vázquez MM, Meza-Serrano E, Lara-Pereyra I, Acuña-González RJ, Alonso-Morales R, Hayen-Valles S, Boeta AM, Zarco L, Lozano-Cuenca J, López-Canales JS, Flores-Herrera H. Equine Placentitis in Mares Induces the Secretion of Pro-Inflammatory Cytokine eIL-1β and the Active Extracellular Matrix Metalloproteinase (MMP)-9. Vet Sci 2023 Aug 22;10(9).
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