Fetal morphological features and abnormalities associated with equine early pregnancy loss
Kahler, A; McGonnell, I M; Smart, H; Kowalski, A A; Smith, K C; Wathes, D C; Mestre, A M
I M McGonnell
A A Kowalski
K C Smith
D C Wathes
A M Mestre
Early pregnancy loss (EPL) occurs in approximately 8% of equine pregnancies, although the aetiology is mostly unknown and embryonic/fetal morphological abnormalities associated with EPL are not defined.
To compare the morphology of EPL to clinically normal embryos/fetuses and previously described embryonic/fetal developmental milestones. To identify morphological abnormalities associated with equine EPL.
Observational case?control study.
Embryos/fetuses were obtained from clinically normal Thoroughbred and pony pregnancies (n = 11) and following EPL from Thoroughbred mares (n = 27). The crown?rump length (CRL) of embryos/fetuses was measured and macroscopic morphology and developmental age were determined independently by three blinded examiners. Sagittal sections of EPL (n = 13) and control (n = 6) embryos/fetuses were assessed microscopically. Fisher's exact test was used to determine significance (P < .05) and correlations were expressed by Pearson coefficient.
Age and CRL were strongly positively correlated in clinically normal Thoroughbred and reference (n = 15, R = .9 (95% CI: 0.8?1.0), R2 = .9, P < .0001) but not EPL embryos/fetuses (n = 19, R = .1 (95% CI: ?0.4 to 0.5), R2 = .01, P = .75). Relative to controls, the CRL of EPL embryos/fetuses was smaller, with evidence of intrauterine growth retardation (IUGR) in 3/8 fetuses assessed. In 9/13 EPL embryos/fetuses, nonspecific neural tissue alterations were identified including disruption of developing pros?, mes? and rhombencephalon and the presence of haemosiderin, indicating premortem haemorrhage. Failed neural tube closure was identified in 1/13 EPL embryos/fetuses. Subcutaneous haemorrhage was present in 14/27 EPL embryos/fetuses.
Autolysis significantly affected 15/27 EPL embryos/fetuses, excluding them from complete assessment. The IUGR reference cut?off values were based on a small number of controls.
Morphological features associated with equine EPL were a mismatch between embryonic/fetal size and age, and alterations of the developing neural tissue and localised subcutaneous haemorrhage. Failed neural tube closure was confirmed as a rare specific abnormality.
Kahler, A., McGonnell, I. M., Smart, H., Kowalski, A. A., Smith, K. C., Wathes, D. C., & Mestre, A. M. (2020). Fetal morphological features and abnormalities associated with equine early pregnancy loss. Equine Veterinary Journal,
|Journal Article Type||Article|
|Acceptance Date||Aug 31, 2020|
|Publication Date||Sep 19, 2020|
|Deposit Date||Oct 7, 2020|
|Publicly Available Date||Nov 20, 2020|
|Journal||Equine Veterinary Journal|
|Peer Reviewed||Peer Reviewed|
|Keywords||Equine, General Medicine|
|Related Public URLs||http://creativecommons.org/licenses/by-nc-nd/4.0/|
|Additional Information||Additional Information : Associated dataset available at: https://doi.org/10.34840/S712-PX78|