Biomedical subjects

S M McDonnell

Publications and source records attributed to S M McDonnell.

8 recordsLinked to original sources

PubMed1992

Manually assisted ejaculation in a stallion with erectile dysfunction subsequent to paraphimosis.

A Thoroughbred stallion with erectile dysfunction following paraphimosis was managed to allow consistent ejaculation. Ejaculation was elicited in this stallion by applying manual stimulation to the base of the penis. This technique allowed consistent ejaculation, and the stallion was able to return to natural service. Historically, stallions with this degree of penile dysfunction have been considered incapable of ejaculation and unable to continue as breeding animals.

Animals↗

PubMed1992

Ejaculatory failure associated with aortic-iliac thrombosis in two stallions.

Two mature breeding stallions were evaluated because of specific ejaculatory dysfunction, and each was found to have aortic-iliac thrombosis occluding 60 to 70% of the aortic lumen. In each case, the stallion had strong libido, normal mounting, and vigorous initial thrusting. With continued exertion, thrusting became weak and dismount was awkward. Treatment aimed at maximizing sexual arousal before mounting and reducing hind limb pain and exertion during breeding allowed these stallions to continue breeding. A program of gradually increasing daily exercise also was associated with improved breeding performance during subsequent breeding seasons. In cases of specific ejaculatory dysfunction, aortic-iliac disease should be included among the differential diagnoses.

Animals↗

PubMed1992

Ejaculation. Physiology and dysfunction.

In summary, important events of ejaculation include emission of sperm and the accessory gland fluids into the urethra, simultaneous closure of the bladder neck, and forceful ejaculation of the combined semen through the urethra. Emission and bladder neck closure are primarily alpha-adrenergically mediated thoracolumbar sympathetic reflex events with supraspinal modulation. Ejaculation is a sacralspinal reflex mediated by the pudendal nerve. In stallions, the most common ejaculation disorders are emission and ejaculation failure, and urine contamination of semen. Rare disorders are azoospermia and premature ejaculation. In a large percentage of cases, an ejaculation appears to be a result of musculoskeletal disorders or to be psychogenic in nature rather than attributable to specific ejaculatory dysfunction. Traditional therapeutic approaches for accommodating deficits can extend the breeding life of many stallions. Pharmacologic aids may be useful.

Animals↗

PubMed1992

Normal and abnormal sexual behavior.

This article includes a brief description of the reproductive patterns and specific behaviors comprising courtship and copulation in equids. The author then focuses on breeding behavior of the domestic stallion. Descriptions of normal breeding behavior under a variety of domestic management systems, comments on sexual behavior of donkeys and exotic equids, and the most common types and treatments of sexual behavior dysfunction are included.

Animals↗

PubMed1991

Use of manual stimulation for collection of semen from an atactic stallion unable to mount.

A 9-year-old atactic breeding stallion was trained to ejaculate, with only manual stimulation, while standing on the ground. Ejaculates obtained yielded fertile semen with morphologic and motility characteristics within the range for normal stallions. This method extended the breeding life of a stallion unable to mount a live or dummy mare or to ejaculate into an artificial vagina while standing on the ground.

Animals↗

PubMed1991

Pasture mating behaviour of donkeys (Equus asinus) at natural and induced oestrus.

The mating behaviour of 2 jacks, each with 21 non-pregnant jennies, was studied when the jennies were in natural oestrus and simultaneously induced oestrus. The main observations were: efficient pasture breeding at natural and induced oestrus, a territorial sociosexual structure, prolonged pre-copulatory interaction, gradual increase of mating activity up to 2 days before ovulation, a copulatory sequence similar to that of horses, vocalization of the jack as a conspicuous behaviour initiating pre-copulatory interaction, frequent heterotypical behaviour of jennies and active involvement of jennies in initiating pre-copulatory interaction.

Animal Husbandry↗

PubMed1989

Gonadotropin releasing hormone (GnRH) affects precopulatory behavior in testosterone-treated geldings.

Twelve pony geldings with (n = 6) and without (n = 6) testosterone replacement (200 micrograms/kg testosterone propionate in oil, SC every 48 hours) received either gonadotropin releasing hormone (GnRH; 25 micrograms SC every 3 hours) or control treatment. Sexual behavior was recorded during 4-minute exposure to an estrous mare, 3 times weekly for 2 weeks before treatment, 3 weeks during treatment, and 3 weeks after treatment had been discontinued. The group receiving testosterone and GnRH (n = 3) exhibited significantly greater flehmen response frequency and attention duration and significantly lower vocalization frequency and erection duration than the group receiving only testosterone (n = 3). GnRH had no apparent effect on sexual behavior in geldings without testosterone replacement (n = 3). These results support an hypothesis of testosterone-dependent, CNS-mediated effects of GnRH on precopulatory behavior in the stallion.

Animals↗

PubMed1987

Pharmacological manipulation of sexual behaviour in stallions.

Series of experiments and clinical trials were conducted to evaluate the effects of psychoneurotropic agents on sexual behaviour of stallions. The benzodiazepine derivative, diazepam (Valium), effectively reversed experimentally suppressed precopulatory arousal and response. Diazepam treatment also blocked the negative effect of novel environment on sexual response. The dibenzazepines imipramine and clomipramine induced erection, masturbation, and ejaculation in the absence of a sexual stimulus.

Animals↗