Sue M. McDonnell

Agonistic ethogram of the equid bachelor band

An ethogram of agonistic and related behaviors among equid bachelor band members was developed. Several key English-language studies on equids were reviewed to derive a preliminary inventory of specific behaviors to be included in the ethogram. A bachelor band of domestic pony stallions pastured together was observed for approximately 50 daylight hours to obtain detailed descriptions of each behavior, enable photographic and video documentation of behaviors, and identify any behaviors to be added to the preliminary inventory. An initial draft of the ethogram was sent to 65 equine researchers for review. Twenty-eight critical reviews were received and their suggestions considered for the final draft. A total of 49 elemental behaviors including five distinct vocalizations was included in the ethogram. Three complex behavioral sequences were also included. Most of the behaviors catalogued from the direct observation of pastured pony stallions were also found in the equid literature. For many, references to these behaviors specifically among males or bachelor band members were not found. The results offer a practical tool for quantitative research and other studies of equid inter-male behavior as well as for teaching of equid behavior, and should facilitate progress toward development of a complete ethogram for the horse and other equids.

Reproductive behavior of stallions and mares: comparison of free-running and domestic in-hand breeding

Based on observational studies comparing social organization and reproductive behavior of equids breeding under feral, semi-feral, and domestic conditions, a series of comparisons and findings on reproductive physiology and behavior are presented. Simple changes in management and handling of mares and stallions that can improve reproductive efficiency and fertility or that can overcome specific breeding problems are discussed.

Color Doppler ultrasound evaluation of testicular blood flow in stallions

The objectives of this study were to evaluate the potential use of color Doppler ultrasound to characterize blood flow to the stallion testis, and to establish reference values for Doppler measures of blood flow in the testicular artery of the stallion. Both testes from each of 52 horses were examined using a pulsed-wave color Doppler ultrasound with a sector array 5/7.5 MHz transducer with a 1mm gate setting. Peak systolic velocity (PSV), end diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) of the testicular artery were measured in each of two locations, the convoluted aspect (spermatic cord) and the marginal aspect of the artery (on the epididymal edge of testis). We found that: (1) all measures were obtainable; (2) except for EDV, the majority of the measures were higher at the cord location than at the marginal aspect of the artery (P < 0.05); and (3) measures for left and right testes were similar (P > 0.10). Resulting measures from 41 of these stallions (82 testes) that appeared free of testicular pathology provide useful reference values for clinical evaluation. Evaluation of 11 cases with testicular pathology suggested further investigation of possible effects of these various conditions on testicular blood flow and testicular function.

Alkaline phosphatase in stallion semen: characterization and clinical applications

Significant amounts of alkaline phosphatase (AP) activity have been found in semen plasma from numerous species. In species in which the majority of semen plasma AP (SPAP) activity originates from the epididymis and testicle, SPAP activity can be used clinically as a marker to differentiate testicular origin azoospermia or oligospermia from ejaculatory failure. Information on SPAP activity in stallions to date has been limited. In this study, a standard clinical chemistry analyzer was used to determine AP activity in pre-ejaculatory fluid and ejaculates from groups of normal stallions. Additionally, accessory glands, epididymides, testicles and other components of the urogenital tract of normal stallions were assayed to determine which tissues contain SPAP activity. The results indicated that levels of AP activity are low in pre-ejaculatory fluid, but significantly higher in ejaculatory fluid from normal stallions. Spermatozoa were not a significant source of SPAP activity. High levels of SPAP activity were found in the testes and epididymides. These findings suggest that SPAP activity is a candidate for a sperm-independent marker for ejaculation in the stallion. Finally, AP activity was determined in ejaculatory fluid from a stallion with bilaterally blocked ampullae, both before and after relief of the blockage. While the blockage was present, AP activity in ejaculatory fluid was low. However, following relief of the blockage, AP activity in ejaculatory fluid rose dramatically, thus suggesting that AP activity will be useful as an inexpensive, simple clinical assay for differentiating ejaculatory failure or excurrent duct blockages from testicular origin azoospermia and oligospermia.

Xylazine-induced ex copula ejaculation in stallions.

This study is a part of ongoing work toward developing pharmacological methods of enhancing and inducing ejaculation in stallions with ejaculatory dysfunction. We evaluated ex copula ejaculatory response to treatment with the alpha-adrenergic agonist xylazine hydrochloride, with and without preliminary sexual stimulation. Twenty-eight mature stallions each received, in random order, one xylazine trial (0.3 mg/lb, i.v.) without preliminary sexual stimulation, one xylazine trial with 5 to 10 min of sexual prestimulation, and one control trial (equivalent volume sterile water injection). Trials were conducted in the animal stalls. Ejaculation occurred in 15 of 56 (27%) xylazine trials. No ejaculations occurred in the sterile water control trials. In trials with sexual prestimulation, ejaculation occurred in 39% compared with 14% in trials without prestimulation. This difference was significant (P<0.05). Xylazine-induced ejaculates were collected into a plastic bag attached to a girth and were similar to those obtained by artificial vagina. Nine of the 15 ejaculations occurred within 2 min of injection.

Pharmacokinetic profile and behavioral effects of gabapentin in the horse.

Gabapentin is being used in horses although its pharmacokinetic (PK) profile, pharmacodynamic (PD) effects and safety in the equine are not fully investigated. Therefore, we characterized PKs and cardiovascular and behavioral effects of gabapentin in horses. Gabapentin (20 mg/kg) was administered i.v. or p.o. to six horses using a randomized crossover design. Plasma gabapentin concentrations were measured in samples collected 0-48 h postadministration employing liquid chromatography-tandem mass spectrometry. Blood pressures, ECG, and sedation scores were recorded before and for 12 h after gabapentin dosage. Nineteen quantitative measures of behaviors were evaluated. After i.v. gabapentin, the decline in plasma drug concentration over time was best described by a 3-compartment mammillary model. Terminal elimination half-life (t(1/2γ) ) was 8.5 (7.1-13.3) h. After p.o. gabapentin terminal elimination half-life () was 7.7 (6.7-11.9) h. The mean oral bioavailability of gabapentin (± SD) was 16.2 ± 2.8% indicating relatively poor absorption of gabapentin following oral administration in horses. Gabapentin caused a significant increase in sedation scores for 1 h after i.v. dose only (P < 0.05). Among behaviors, drinking frequency was greater and standing rest duration was lower with i.v. gabapentin (P < 0.05). Horses tolerated both i.v. and p.o. gabapentin doses well. There were no significant differences in and . Oral administration yielded much lower plasma concentrations because of low bioavailability.

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.

Manual stimulation collection of semen from stallions: Training time, sexual behavior and semen

Abstract In Experiment 1, 31 pony stallions of unknown breeding history were trained to either manual stimulation (n = 20) or traditional artificial vagina (n = 11) collection of semen. For manual stimulation, 45% achieved ejaculation on the ground during the initial training session. The remaining 55% achieved ejaculation by manual stimulation while mounted during the first or second training session. For artificial vagina training, 73% ejaculated during the first training session. The mean number of training sessions required was 1.15 for the manual stimulation technique and 1.18 for the traditional artificial vagina technique. Experiment 2 was conducted to compare sexual behavior and the semen obtained by manual stimulation and artificial vagina procedures. Six stallions which had been trained for manual stimulation collection of semen in Experiment 1 were used. Semen was collected from each stallion in two replicates of four collections per replicate, during which each stallion was exposed alternately on four successive days to manual stimulation or artificial vagina technique. There were no significant differences due to the method of collection in total collection time, number of mounts required, or mount to ejaculation latency. Manual stimulation required a mean of nine thrusts, while the artificial vagina method required only six. This difference was significant (P

Oral imipramine and intravenous xylazine for pharmacologically-induced ex copula ejaculation in stallions

This study is part of ongoing work toward developing pharmacological methods for enhancing and inducing ejaculation in stallions with ejaculatory dysfunction or disabilities that interfere with normal breeding behavior. The objective was to evaluate a treatment regimen involving oral imipramine followed by intravenous xylazine that, in uncontrolled field clinical trials, had shown promise for a higher rate of ejaculation and fewer side effects using a more easily obtained and administered form of imipramine. Eight stallions each underwent eight trials in which treatment consisted of imipramine hydrochloride (3mg/kg, orally in a small portion sweet feed) followed 2h later by xylazine hydrochloride (0.66 mg/kg, intravenously). Trials were conducted with the stallion in a stall. Semen was collected using a collection bag secured over the prepuce with a girth band. Overall, 44 of the 64 attempts (68%) resulted in ejaculation. Within-stallion ejaculation rate ranged from 3 of 8 to 7 of 8 attempts. Interval from xylazine treatment to ejaculation ranged from 1.2 to 14 min. As is typical for induced ejaculations in which imipramine is included in the treatment regimen, ejaculates were of low volume, high sperm concentration, and with a higher total number of sperm than for in copula ejaculates of these stallions. These results represent a modest improvement in rate of ejaculation over previous treatment regimens.

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.