Pregnancy Diagnosis in Horses
by Robert N. Oglesby DVM
Introduction
Introduction
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Experience Counts
»
Ultrasound
»
Pregnant Mares Do Not Return to Heat (Usually)
»
Rectal Palpation
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Hormonal Changes
»
Visual Assessment
»
More Info & Discussions
The determination of pregnancy in a broodmare is an important aspect of any breeding program. With natural service these are fairly easy to determine, on most mares. But with the increase of artificial insemination (AI) many breeding mares today are on farms where there is no stallion on site to constantly tease mares. Even when there is a stallion and good teasing practices are used, a percentage (appx. 10%) of normal mares may be difficult to tell if they have come back into heat following breeding. Because a mare only ovulates once every 21 days the accurate timing of insemination and the early detection of non-pregnant mares helps prevent a late season foal or missed season all together. This article discusses the various techniques available, including hormonal changes for checking miniature horses, to the horseman and veterinarian for a pregnancy diagnosis in equines and their relative advantages and disadvantages. Links to related articles and scientific reports are also present.
Note: the following article discusses different ways to determine if a mare is pregnant. The techniques are presented roughly in order of how early they can detect pregnancy.
Experience Counts
Introduction
»
Experience Counts
»
Ultrasound
»
Pregnant Mares Do Not Return to Heat (Usually)
»
Rectal Palpation
»
Hormonal Changes
»
Visual Assessment
»
More Info & Discussions
No matter what technique is used in reproductive work, experience is an important factor in the accuracy of the assessment. For most people it still requires years of experience to become proficient at rectal palpation. Cornell University believes it takes 100 mentor-guided rectal palpations to become minimally proficient. You would be surprised at the variations you run into commonly with mares whether you are discussing heat, ovulation, or pregnancy.
"Days Pregnant" are Calculated from the Day of Ovulation
When you talk about how old is a fetus the most reliable date is counting forward from the day of ovulation. Now most people do not get to observe this event so it is very important to remember:
ovulation generally occurs the day before a mare goes out of heat. This should be counted as day one. The most important exception to this rule is when you have a double ovulation which may throw calculations off as much as three or four days. The only way you might know this is through palpation and ultrasound during extrus.
Ultrasound
Introduction
»
Experience Counts
»
Ultrasound
»
Pregnant Mares Do Not Return to Heat (Usually)
»
Rectal Palpation
»
Hormonal Changes
»
Visual Assessment
»
More Info & Discussions
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