The mare, on the average, has an estrous period that lasts around 6.5 days. Most mares will ovulate follicles ranging between 40 and 45 mm, 24–48 h before the end of their standing heat. Therefore, mares can show strong signs of heat up to 48 h after ovulation. Although these parameters are well established for the average mare, follicle size at ovulation and the duration of estrus in mares var...

Measurements every day or every other day showed that testosterone levels ranging from 15 to 70 pg/ml were higher at oestrus in 4 of the 6 mares studied. In these 4 mares, another testosterone peak occurred 11--13 days before the next oestrus either before (3 mares) or after the fall in progesterone levels.

Pregnancy rates after frozen semen inseminations (AI), particularly in older and problem mares, are lower than after fresh semen AI. Uterine contractility and the inflammatory reaction after frozen semen insemination were studied in two groups of mares: the abnormal group comprised of 6 old barren mares categorized in biopsy category IIB or III, and the control group including 6 reproductively ...

BACKGROUND Pseudomonas aeruginosa may cause venereal disease and infertility in horses. A Pseudomonas aeruginosa - carrier stallion, often unresponsive to artificial vagina collection, was used to naturally breed mares. Semen collected from the same stallion was also used to perform artificial inseminations. Pregnancy rates, embryo quality and incidence of uterine infection were compared betwee...

OBJECTIVE To compare larvicidal regimens of fenbendazole and moxidectin for reduction and suppression of cyathostomin fecal egg counts (FEC) in a transient herd of embryo transfer-recipient mares. DESIGN Randomized, complete block, clinical trial. ANIMALS 120 mares from 21 states, residing on 1 farm. PROCEDURES An initial fecal sample was collected from each mare; mares with an FEC ≥ 200 ...

Discomfort in farm animals may be induced by inappropriate types or timing of food supplies. Thus, time restriction of meals and lack of roughage have been shown to be one source of emergence of oral stereotypies and abnormal behaviour in horses which have evolved to eat high-fibre diets in small amounts over long periods of time. This feeding pattern is often altered in domestic environment wh...

Fetal determination has been conducted for almost 20 yr. In 1989, Curran and Ginther first identified fetal gender by evaluating the location of the genital tubercle in the male and female fetus using transrectal examination between 54 and 84 days of gestation. More recently, others 4 have described fetal-gender determination in midand late pregnancy using a transabdominal technique. Knowing fe...

On February 4, 14 of 28 seasonally anestrous mares were fed .044 mg per kilogram of body weight of an oral progestin, allyl trenbolone (17a-allyl-estratriene 4-9-11, 17/3-ol-3-one) for 12 days. There was no difference (P>.05) between groups for the number of mares exhibiting estrus after treatment or follicular activity during or after treatment. After March 6, 18 mares that had not yet ovulate...

The paternal origins of Thoroughbred racehorses trace back to a handful of Middle Eastern stallions, imported to the British Isles during the seventeenth century. Yet, few details of the foundation mares were recorded, in many cases not even their names (several different maternal lineages trace back to 'A Royal Mare'). This has fuelled intense speculation over their origins. We examined mitoch...

The potency, toxicity and clinical value of two synthetic analogues of Prostaglandin F2(ICI-7()939 and ICI-8ioo8) for inducing luteolysis in mares is discussed. Measurement of peripheral plasma progestagen levels in over 4oo Thoroughbred mares has demonstrated that abnormal persistence of luteal function (prolonged dioestrus) is the major cause of the failure of nonpregnant mares to exhibit reg...