Tuesday, March 3, 2009

Options To Prevention Of Twin Conception

Options To Prevention Of Twin Conception

Avoid mating mares with two follicles; then use prostaglandins to shorten the interval to the next oestrus. Remember the mare may not be examined regularly enough for detection of two follicles the mare may produce two follicles again at the next heat (this is common) it may be too late in the breeding season to miss mating at this heat. Detection of two follicles may be difficult by rectal palpation alone because;

Two follicles close to each other may feel like one large follicle on palpation, but these can be easily recognised by ultrasound examination) a follicle deep in the ovary may not be detected by palpation (but would be seen imaged by ultrasound examination) a second follicle, unsuspected by palpation or ultrasound, may develop and ovulate during early dioestrus; if the mare was mated close to the first ovulation by a stallion with good semen longevity a second pregnancy could occur.

Try to mate between two anticipated ovulations, on the assumption that the ovum released before mating is unlikely to be fertilised. Remember mating within 12 hours of an ovulation can still result in a conception both ovulations may occur between successive examinations ,the mare may go out of season before she has been mated such timing requires regular repeated examinations.

Diagnosis Of Twins Manual Palpation, When twin pregnancies are in the same horn, they produce a single swelling at its base. This swelling often feels no bigger than a single pregnancy of the same age. Twins which are located in separate horns are easier to detect as two distinct swellingsEven under ideal conditions this can be no more than 50% accurate, as in about one-half of twin pregnancies both conceptuses are in the same uterine horn.

Remember, pregnancy examination at 21 days may miss these bicornual twins (in separate horns) as the younger conceptus may not yet produce a palpable swelling bicornual twins may be more difficult to detect in the post-partum uterus, The latest time for identification of bicornual twins by palpation is about 60 days - after this the two swellings become indistinguishable. However, if twin pregnancy is to be terminated to give the mare a second chance to conceive during the current breeding season, diagnosis should preferably be before day 30.

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