Alternative Protocol Using Imipramine,Detomidine, and Oxytocin for Semen Collection in Stallion with Ejaculatory Dysfunction

A 7-year-old Quarter Horse stallion was admitted at the hospital with a history of ejaculatory failure for 12 months. The stallion revealed no physical or psychological abnormalities, as well as, normal libido and erection. In addition, there were no abnormalities in accessory sex glands or the aorta artery detected by transrectal ultrasonography. Based on clinical findings, the stallion was diagnosed with an idiopathic ejaculatory dysfunction; therefore, alternative attempts of semen collection were performed. Thermal compress on the basis of the stallion’s penis, semen collection on the ground, and imipramine hydrochloride treatment were performed unsuccessfully. However, a protocol consisted by the association of imipramine (3 mg/kg/v.o.), detomidine (0.02 mg/kg/i.v.), and oxytocin (20 U.I./i.v.) successfully produced ejaculation in this stallion. The semen obtained from ex copula ejaculation of the stallion was collected using a collector cup lined with a plastic bag, which was positioned over the prepuce of the stallion. Semen with good sperm quality (87% of total motility) was obtained using the proposed protocol. Semen was then processed for cryopreservation and post-thawed semen samples presented satisfactory sperm parameters. In conclusion, the association of imipramine, detomidine, and oxytocin can be considered for ex copula semen collection in stallions.     

Retrograde ejaculation in a stallion

Retrograde ejaculation was diagnosed in a 10-year-old Arabian stallion. Despite behavioral signs consistent with ejaculation, the collection receptacle of an artificial vagina remained devoid of semen on numerous occasions. Catheterization of the urinary bladder yielded large numbers of spermatozoa, even when an ejaculate was obtained, whereas low numbers (< 1 X 10(6)/ml) of spermatozoa are found in the bladder of clinically normal stallions after ejaculation. Endoscopic examination of the urethra, seminal colliculus, and bladder failed to reveal abnormalities. Medical treatment with imipramine hydrochloride apparently resulted in improvement initially, but was not curative. Further diagnostic and treatment measures were declined and the stallion was castrated. For stallions that seemingly fail to ejaculate or for ejaculates that contain lower seminal volumes or numbers of spermatozoa than expected, obtaining a urine sample after ejaculation via bladder catheterization is a simple diagnostic procedure that may be used to investigate the possibility of retrograde ejaculation.     

Transrectal ultrasonography for the evaluation of stallion accessory sex glands.

This article reviews the capabilities of transrectal ultrasonography for determining the distribution of fluid and tissue within stallion accessory sex glands. Emphasis is placed on describing the normal ultrasonographic appearance of the accessory sex glands, excurrent ducts, and pelvic urethra of stallions during rest, after teasing, and after ejaculation and using this information to detect glandular abnormalities.     

Training the novice stallion for natural breeding.

There are myriad problems that can arise when training the novice stallion for natural service. Many problems can be avoided by proper early training of the novice stallion. In the final analysis, common sense should prevail. The major ally of common sense is patience. One should keep in mind that the goal is to have a stallion behave in a disciplined manner, allowing for his expression of libido and effective mounting, intromission, and ejaculation. This is accomplished through judicious training and, as with any training process, takes some time and work. Proper training will help circumvent many potential problems and make the ultimate goal of impregnating mares more efficient.     

Measurement of Concentration and Viability in Stallion Sperm

Sperm concentration and sperm membrane intactness (SMI) or viability are two measures of sperm quality that provide important but different information about a stallion's reproductive capability. Sperm concentration is a measure that, by itself, informs little about the reproductive status of either the stallion or the ejaculate. Nevertheless, it is part of the product, along with semen volume, that determines total sperm number. The correct calculation of total sperm number directly affects the number of mares a stallion can breed and therefore, fertility. If either sperm concentration or semen volume is incorrectly measured, both the number of mares that a stallion can breed and the fertility of those breedings are affected. Although considerable between-stallion variation exists, sperm concentration, semen volume and total sperm number tend to be seasonal and vary with ejaculation frequency.     

Endoscopic Laser Ablation of a Midline Cyst of the Colliculus Seminalis as a Treatment for Anejaculation in a Stallion

An 18-year-old Appaloosa stallion presented with a history of ejaculatory dysfunction, which had recently progressed to an inability to ejaculate (anejaculation). Transrectal ultrasound evaluation revealed the presence of a prominent midline cyst of the colliculus seminalis, which was compressing the most terminal parts of the deferent ducts. Both ducts were enlarged and filled with hyperechoic content. The stallion was diagnosed with a complete occlusion of the deferent ducts because of the compression from the midline cyst of the colliculus seminalis. To date, there are no established treatments for this condition in stallions, although several procedures have been successfully used in men affected by similar problems. Therefore, we proposed performing one of these procedures—a laser ablation of the cyst to collapse it and to open the ejaculatory path. The stallion was placed under general anesthesia, and an endoscopic ultrasound-guided laser ablation of the cyst was performed. No immediate or long-term complications were observed. After the expulsion of accumulated material, the stallion produced normal semen and successfully impregnated mares during the next breeding season.     

Characterization of semen collected by pharmacologically induced ejaculation from a stallion with seminal vesiculitis

The present study compared the quality of sperm collected by artificial vagina or pharmacologically induced ejaculation from a 10-year-old thoroughbred stallion with seminal vesiculitis. The pharmacological protocol involved intravenous administration of detomidine (0.01 mg/kg) and oxytocin (20 IU) and successfully induced ejaculation in all attempts of semen collection. Sperm motility, plasma membrane and acrosome integrity (PMAI), reactive oxygen species (ROS) levels, polymorphonuclear neutrophil (PMN) percentage, and bacterial profiles of fresh and cooled semen (5°C for 24 hr) were evaluated. Semen obtained by the pharmacological method presented reduced seminal volume, decreased PMN percentage and superior sperm motility in cooled samples. Moreover, higher PMAI and lower ROS levels were observed in semen collected by the pharmacological method. Therefore, pharmacologically induced ejaculation is an alternative to obtain semen with minimal contamination and with sperm of superior quality and longevity from stallions with seminal vesiculitis.     

The effect of a surgically created shunt between the corpus cavernosum penis and corpus spongiosum penis of stallions on erectile and ejaculatory function

OBJECTIVE: To evaluate the effect of a shunt created between the corpus cavernosum penis (CCP) and corpus spongiosum penis (CSP) on erectile and ejaculatory function of normal stallions and to verify persistence of the shunt. STUDY DESIGN: The capability of stallions to develop an erection and to ejaculate was evaluated before and after creation of a corporeal shunt. Persistence of the shunt was determined by dye injection into the CCP at necropsy. ANIMALS: Six stallions. METHODS: A CCP-CSP shunt was created in five stallions. Semen was collected before and 4 to 14 weeks after surgery, before the horses were euthanatized. Dye was injected into the CCP to determine persistence of the shunt. Dye was also injected into the CCP of a control stallion. RESULTS: All stallions had normal erectile and ejaculatory function before and after surgery. Dye, injected into the CCP, entered the CSP in three of five treated stallions, demonstrating persistence of the shunt, whereas in two stallions, dye was found only in the CCP, indicating closure of the shunt. No dye was detected in the CSP of the control stallion. CONCLUSIONS: Creation of a corporeal shunt does not interfere with normal erection and ejaculation of stallions. Shunt closure is not necessary for stallions to retain normal erectile and ejaculatory function. CLINICAL RELEVANCE: Failure of a stallion affected by priapism to achieve normal erection or to ejaculate after creation of a corporeal shunt would likely be because of damage to corporeal tissue than from an effect of the shunt.     

Expression of Prostate Glycoconjugates in the Stallion and Castrated Horse

This work was undertaken to determine the glycoconjugates secreted by the epithelium of the prostate in the intact stallion and castrated horse using lectin histochemical procedures in conjunction with enzymatic digestion and deglycosylation treatments. Additionally, anti‐5 and 13‐16‐cytokeratin antibodies were used to localize epithelial basal cells. In the stallion, lectin histochemistry showed the following sugar residues in the Golgi zone of the glandular cells: α‐Glu/Man, α‐Fuc and β‐Gal included in both O‐ and N‐linked oligosaccharides as well as β‐GalNAc, GlcNAc and α‐Gal, which belonged to O‐glycoproteins. β‐Gal and β‐GalNAc moieties were also noted subterminal to sialyl residues. Sialic acid specific lectins identified Neu‐5Ac(α2,3‐6)‐β‐Gal or Neu5Ac(α2,6)‐β‐GalNAc sequences in both N‐ and O‐bound glycoproteins. The prostatic glandular cells of the castrated horse expressed some of the same sugar moieties found in the stallions, such as α‐Glu/Man, α‐Gal and GlcNAc, but significant differences were also noted. In particular, β‐D‐GalNAc was only detected subterminal to sialic acid, β‐D‐Gal‐(1‐3)‐D‐GalNAc was found in N‐linked glycans, whereas β‐D‐Gal‐(1‐4)‐D‐GlcNAc and Neu5Acα2,6Gal/GalNAc were noted only in O‐glycoproteins. These results indicate that the lectin binding patterns in glandular cells may be modified by sex hormones. No specific lectin labelling of basal cells was found in either the stallion or the castrated horse even though they were immunostained with specific anti‐cytokeratin antibodies. These cells stained more strongly in the castrated horse than in the intact stallion suggesting that they are androgen responsive. The glycomolecules detected in the equine prostate secretions may contribute to the remodelling of the sperm surface, which occurs during sperm transit through the male genital tract and also after ejaculation in the seminal plasma. These changes may be important in the understanding of the stallion fertility.     

Semen collection techniques.

Semen collection techniques in the stallion have evolved considerably over the last 70 to 80 years and are used today primarily for artificial insemination. Semen can be collected from stallions that are otherwise unable to breed, allowing continued use of valuable animals. There are many options for collection of semen from stallions that present with ejaculatory dysfunction (see the article by McDonnell elsewhere in this issue.) Although there are many advantages to the use of artificial breeding, the collector must understand each step of the collection procedure as well as stallion preferences and proper use of an artificial vagina and mount source so that a representative semen sample is collected.     

Haemolytic anaemia as a complication following colic surgery in a 10‐year‐old Arabian stallion

Immune‐mediated haemolytic anaemia is rare in the horse. This case report discusses the clinical presentation and treatment of this condition in an Arabian stallion following abdominal surgery for large colon volvulus. On Day 10 of hospitalisation the stallion's PCV dropped by 10% whilst his total solids remained stable, consistent with haemolytic anaemia. The stallion was treated with whole blood transfusions and dexamethasone and recovered to be discharged on Day 42. This is an interesting example of immune mediated haemolytic anaemia associated with a complicated gastrointestinal condition. It demonstrates the wide variety of potential aetiologies underlying a haemolytic episode and the necessity for expedient treatment.     

Bacterial epididymitis in two stallions

Two stallions had unilateral bacterial epididymitis attributable to S zooepidemicus infection. Diagnosis was based on bacterial isolation, WBC in the semen, higher than normal blood fibrinogen concentration, and leukocytosis with regenerative left shift. One horse had high seminal pH. Ultrasonography of the involved epididymides revealed changes consistent with the appearance of abnormal accumulation of exudate in the tail of the epididymis. Treatment included unilateral orchiectomy and antibiotic administration. In stallion 1, the infection persisted despite treatment. Treatment result was not available for stallion 2.     

Serially determined plasma alpha-tocopherol concentrations and results of the oral vitamin E absorption test in clinically normal horses and in horses with degenerative myeloencephalopathy

Plasma alpha-tocopherol (vitamin E) values were monitored serially in 9 foals sired by a stallion with equine degenerative myeloencephalopathy (EDM) and in 5 age-matched control foals (sired by a clinically normal stallion) raised in the same environment for the first year of life. Clinical evaluation determined that 8 of the 9 foals sired by the stallion with EDM had neurologic deficits consistent with the disease on one or more occasions during the study period, whereas control foals had normal gait. From 6 weeks to 10 months of age, plasma alpha-tocopherol values in foals with signs of EDM were significantly (P less than 0.001) lower than those in control foals. An oral vitamin E absorption test was performed, and results for 8 of the affected horses and the affected stallion were compared with results for 4 of the monitored control horses and 4 additional control horses. Significant differences were not evident in any of the absorption indices. On the basis of data from this study and supported by reported prophylactic and therapeutic benefits of supplemented vitamin E, low plasma concentration of vitamin E is concluded to be a factor in the development of EDM in the first year of life of hereditarily predisposed foals. It was also concluded that the significantly lower alpha-tocopherol values seen in the foals in this study did not reflect a primary gastrointestinal tract absorption problem.     

Bilateral Testicular Mixed Germ Cell-sex Cord-stromal Tumours in a Stallion

An 18-year-old Friesian stallion was examined approximately one week after reportedly presenting scrotal swelling due to torsion of the spermatic cords. Upon presentation no scrotal swelling was noted, the testes were normally oriented, and no abnormalities of the spermatic cords were noted. However, both testes were smaller than expected for a mature stallion and deep palpation revealed that the consistency of the testes was nodular. Ultrasonographic evaluation of the testes revealed diffuse heterogeneous parenchyma with multiple hypoechoic nodular areas. Grossly, the testicular parenchyma was effaced by multiple gray-tan nodules of varying consistency interspersed with gray-white bands of tissue. Microscopic analysis revealed multiple pleomorphic neoplastic foci disseminated throughout both testes. Histological and immunohistochemical features were atypical and consistent with the diagnosis of bilateral testicular mixed germ cell-sex cord stromal tumours. Bilateral testicular tumours and testicular mixed cell tumours are extremely rare in stallions and this is the first report of bilateral testicular mixed germ cell-sex cord-stromal tumours in a stallion. Our findings indicate that certain ultrasonographic characteristics are suggestive of testicular tumour and that immunohistochemistry markers can be used to better characterize testicular neoplasms in stallions.     

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.     

Identification of degenerative germ cells in semen from a quarter horse stallion

A 3-year-old Quarter Horse stallion was presented for evaluation of potential fertility. An impairment in spermatogenesis was suspected as the stallion produced semen with reduced percentages of progressively motile and morphologically normal spermatozoa. In addition, when semen was collected daily from the stallion, daily spermatozoal output (DSO) was found to be below normal. Semen from this stallion also contained spherical cells of unknown origin. The following report describes the identification of these cells as degenerating spermatids by the use of light and electron microscopy.     

Management Options for the Aged Breeding Stallion with Declining Testicular Function

In our experience, the testicular dysfunction that develops in aged stallions is typically progressive, contributing to a gradual deterioration in sperm output and quality over 2-4 years. As the ability to produce sufficient numbers of normal sperm in ejaculates declines, so do pregnancy rates until the stallion eventually becomes so subfertile that it is no longer commercially feasible to continue breeding. However, more intensive breeding management can sometimes result in pregnancy rates (per cycle and per season) that are sufficient to justify breeding of the aged stallion to a diminishing number of mares during the period of declining fertility.     

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.     

Caspase Activation,Hydrogen Peroxide Production and Akt Dephosphorylation Occur During Stallion Sperm Senescence

To investigate the mechanisms inducing sperm death after ejaculation, stallion ejaculates were incubated in BWW media during 6 h at 37°C. At the beginning of the incubation period and after 1, 2, 4 and 6 h sperm motility and kinematics (CASA), mitochondrial membrane potential and membrane permeability and integrity were evaluated (flow cytometry). Also, at the same time intervals, active caspase 3, hydrogen peroxide, superoxide anion (flow cytometry) and Akt phosphorylation (flow cytometry) were evaluated. Major decreases in sperm function occurred after 6 h of incubation, although after 1 h decrease in the percentages of motile and progressive motile sperm occurred. The decrease observed in sperm functionality after 6 h of incubation was accompanied by a significant increase in the production of hydrogen peroxide and the greatest increase in caspase 3 activity. Additionally, the percentage of phosphorylated Akt reached a minimum after 6 h of incubation. These results provide evidences that sperm death during in vitro incubation is largely an apoptotic phenomena, probably stimulated by endogenous production of hydrogen peroxide and the lack of prosurvival factors maintaining Akt in a phosphorylated status. Disclosing molecular mechanisms leading to sperm death may help to develop new strategies for stallion sperm conservation.     

Azoospermia associated with bilateral segmental aplasia of the ductus deferens in a stallion

A 3-year-old Quarter Horse halter stallion was referred for routine semen evaluation. Physically, the stallion's reproductive organs appeared normal. Repeated semen evaluations did not reveal any spermatozoa. Because high activities of alkaline phosphatase are detected in the epididymal fluid and indicative of complete ejaculation, alkaline phosphatase activities were analyzed in several samples, which yielded activities far less than reference values and suggested a blockage of the reproductive tract. Endoscopic evaluation of the urethra and the bulbourethral, prostate, and urethral gland ducts did not reveal abnormalities. The left ductus deferens was exposed surgically, and attempts to pass a catheter through it in a normograde direction met resistance after 20 cm. Laparoscopic abdominal surgery revealed the ductus deferens tapered to a thin structure just cranial to the entrance in the urogenital fold, cranial and lateral to the bladder. Both ductus deferentia were similarly affected. The symmetry and bilateral nature of the abnormalities were strong indications of a possible congenital defect.