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in Journal of the American Veterinary Medical Association

Objective

To evaluate the effects of trimethoprim-sulfamethoxazole and pyrimethamine treatment on various measures of reproductive function in healthy pony stallions.

Design

Randomized complete block study.

Animals

12 healthy, mature pony stallions.

Procedure

Stallions were assigned to treatment and control groups balanced for age and various characteristics of reproductive function. The treated group received trimethoprim-sulfamethoxazole and pyrimethamine for 90 days during summer and fall; the control group was not treated. Semen characteristics, sexual behavior, testicular volume, and sperm production efficiency were evaluated before treatment started and at 30-day intervals until 60 days after treatment ended.

Results

Effects of treatment were not detected for semen characteristics, testicular volume, sperm production efficiency, libido, erection, and quantitative measures of ejaculatory efficiency. At 30, 60, and 90 days, 4 of 6 treated stallions had unsteadiness upon mounting, clumsy or weak thrusting, failure to flex the back, and thready or inapparent ejaculatory pulses that resulted in dribbling of semen rather than forceful expulsion.

Conclusions and Clinical Relevance

Although treatment with trimethoprim-sulfamethoxazole and pyrimethamine may not affect semen quality, testicular volume, sperm production efficiency, erection, or libido of healthy stallions, treatment may induce changes in copulatory form and agility and alter the pattern and strength of ejaculation. Stallions that develop neurologic signs during treatment should be used with caution for breeding. (J Am Vet Med Assoc 1999;215:1317–1319)

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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the efficiency of foal production following intracytoplasmic sperm injection (ICSI) and blastocyst culture of oocytes from mares that died or were euthanized under field conditions.

Design—Prospective case series.

Animals—16 mares (age, 3 to 19 years) that died or were euthanized for various causes.

Procedures—Ovaries were collected immediately before euthanasia (n = 10) or after death (6). Ovaries were transported to the laboratory for oocyte recovery (15 mares), or oocytes were recovered at a remote location and shipped to the laboratory (1). Oocytes underwent ICSI, and presumptive zygotes were cultured for 7 to 10 days. Blastocysts were shipped to embryo transfer facilities for transcervical transfer to recipient mares.

Results—Ovaries were processed 30 minutes to 12 hours (mean ± SD, 4.6 ± 3.3 hours) after mares' deaths. A mean of 14.1 ± 8.6 oocytes/mare were cultured, and 110 of 225 (49%) matured. Twenty-one blastocysts developed after ICSI and were transferred to recipient mares. Thirteen pregnancies were established; 10 healthy foals were produced from 6 donor mares. The number of blastocysts produced per mare and number of live foals produced per mare were significantly correlated with the number of oocytes recovered.

Conclusions and Clinical Relevance—Foals were produced from mares after death or euthanasia under field conditions. Proportions of foals born overall (10 foals/16 mares) and mares from which ≥ 1 foal was produced (6/16) were greater than those reported following recovery and oviductal transfer of oocytes to inseminated recipients after death of donor mares under field conditions.

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in Journal of the American Veterinary Medical Association