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Henderson KM, Perkins NR, Wards RL, et al. Enzymeimmunoassay of oestrone sulphate concentrations in faeces for non-invasive pregnancy determination in mares. N Z Vet J. 1999;47(2):61-6doi: 10.1080/00480169.1999.36112.
Henderson, K. M., Perkins, N. R., Wards, R. L., & Stewart, J. I. (1999). Enzymeimmunoassay of oestrone sulphate concentrations in faeces for non-invasive pregnancy determination in mares. New Zealand veterinary journal, 47(2), 61-6. https://doi.org/10.1080/00480169.1999.36112
Henderson, K M, et al. "Enzymeimmunoassay of oestrone sulphate concentrations in faeces for non-invasive pregnancy determination in mares." New Zealand veterinary journal vol. 47,2 (1999): 61-6. doi: https://doi.org/10.1080/00480169.1999.36112
Henderson KM, Perkins NR, Wards RL, Stewart JI. Enzymeimmunoassay of oestrone sulphate concentrations in faeces for non-invasive pregnancy determination in mares. N Z Vet J. 1999 Apr;47(2):61-6. doi: 10.1080/00480169.1999.36112. PMID: 16032072.
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N Z Vet J. 1999 Apr;47(2):61-6. doi: 10.1080/00480169.1999.36112.

Enzymeimmunoassay of oestrone sulphate concentrations in faeces for non-invasive pregnancy determination in mares.

New Zealand veterinary journal

K M Henderson, N R Perkins, R L Wards, J I Stewart

Affiliations

  1. AgResearch, Wallaceville Animal Research Centre, PO Box 40-063, Upper Hutt, New Zealand.

PMID: 16032072 DOI: 10.1080/00480169.1999.36112

Abstract

AIM: To determine the suitability of measuring faecal oestrone sulphate (OS) by enzymeimmunoassay as a means of determining pregnancy status in mares bred under New Zealand conditions.

METHODS: An antibody-coated microtitre plate-based enzymeimmunoassay was used to determine the concentration of OS in faecal and plasma samples obtained from pregnant and non-pregnant mares.

RESULTS: In non-pregnant mares, the mean faecal OS concentration was 34 ng/g, and the value three standard deviations above this was 80 ng/g. None of 427 faecal samples collected from 116 non-pregnant mares over a l-year period had an OS concentration >80 ng/g. Only five samples from three mares had an OS concentration >65 ng/g, the value two standard deviations above the mean non-pregnant value. Analysis of faecal OS concentrations in 532 faecal samples collected from 39 pregnant mares showed that as pregnancy progressed, an increasing proportion of faecal samples had OS concentrations >80 ng/g. None of the mares 150 days or more pregnant had faecal OS concentrations <50 ng/g, and 204/220 samples obtained from these mares had faecal OS concentrations >80 ng/g. Following foaling or foetal death, elevated faecal OS concentrations returned quickly to non-pregnant levels. The mean +/- s.e.m. plasma level of OS in five mares bled daily throughout one oestrous cycle was 1.7 +/- 0.2 ng/ml. Sixty-eight blood samples from pregnant mares bled up to five times between 92 days after mating and foaling all had plasma OS concentrations >30 ng/ml, with 64/68 being >50 ng/ml.

CONCLUSIONS: This study shows that measuring faecal OS concentrations by enzymeimmunoassay offers a convenient, accurate, non-invasive means of determining pregnancy status in mares from 150 days after mating onwards. Mares with faecal OS concentrations <50 ng/g can be considered not pregnant, while mares with faecal OS concentrations >80 ng/g can be considered pregnant. Those few mares returning a faecal OS concentration between 50 and 80 ng/g should be retested to obtain a conclusive result. Measuring plasma OS concentrations allows pregnancy status to be determined earlier (from 100 days after mating). Moreover, the discrimination between non-pregnant and pregnant levels is greater for OS in plasma than in faeces.

CLINICAL RELEVANCE: Measurement of OS concentrations in faeces provides an alternative and non-invasive means of determining pregnancy status in mares from 150 days after mating.

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