Equine castration: A review of techniques, complications and their management

Development and Evaluation of a Surgical Simulator and Assessment Rubric for Standing Castration of the Horse

In veterinary education, simulators are models or devices that can imitate a real patient or scenario and allow students to practice skills without the need for live patients. Castration is a common surgical procedure in all species, and the standing, open technique is frequently performed in horses. Although a simulator has been developed for equine closed castration, a simulator for standing castration in the horse has not yet been described. This two-part study focused on the design, creation, and evaluation of a simulator for teaching standing castration in the horse. A low-technology simulator was created using molded silicone testicles, cohesive bandage, stockings, and socks. A rubric was created for assessing performance using the simulator. Participants were recruited from three groups: university academic staff members (n = 12, majority equine veterinarians), equine veterinarians working in private practice (n = 9), and final-year veterinary students (n = 28). Each group tested the simulator while being graded using the developed rubric, and participants completed an anonymous online feedback questionnaire. Feedback was positive overall, with 98% of respondents (n = 48/49) stating that the model would be a useful addition to the veterinary curriculum. Furthermore, 100% of students reported that using the simulator increased their confidence in performing standing castration in horses. Evaluation of the model included assessment of responses from veterinarians and students regarding realism and usefulness of the simulator, comparison of rubric scores between veterinarians and students, and assessment of the reliability of the rubric. Median student rubric score was significantly lower than qualified veterinarians (p < .001), and Cronbach's alpha demonstrated that there was adequate internal reliability in rubric scoring (α = .85). It was determined that the simulator is effective for teaching the steps of the surgical procedure and for increasing student confidence.

Limited association between stallion-like behavior and hormonal indicators of testicular remnants in geldings

Persistent stallion-like behavior is a common sign of cryptorchidism in supposed geldings. The presence of testicular tissue can be evaluated by analyzing hormones such as testosterone and anti-Müllerian hormone (AMH). Here, we used hormonal analysis to investigate relationships between the likely presence of testicular tissue and stallion-like behavior in samples submitted from presumptive geldings (n = 1,202), retrospectively. Most geldings with stallion-like behaviors had serum concentrations of testosterone (851/1,056; 80.6 %) and AMH (682/877; 77.8 %) below the laboratory reference range for cryptorchids (< 60 pg/mL and ≤ 0.15 ng/mL for testosterone and AMH, respectively). A total of 13 samples (13/716; 1.8 %) showed AMH concentrations typical for geldings but testosterone above the cryptorchid range. Conversely, 31 samples (31/716; 4.3 %) had high AMH, suggesting cryptorchidism, but testosterone concentrations implied no testicular tissue. Among the cryptorchid stallions, the AMH and testosterone concentrations did not vary based on the season. However, age categories affected the concentration of both hormones among the presumptive true cryptorchid stallions. The results of this study demonstrate that undesirable behavior in geldings is rarely associated with the presence of testicular tissue, as assessed by these two hormonal biomarkers. This information highlights the complexity of behavior and demonstrates that persistent stallion-like behavior in geldings could be related to factors other than the presence of testicular tissue.

Evaluation of the in vitro performance of the double forwarder knot, compared to square and surgeon's knots using large gauge suture

OBJECTIVE

The aim of the study was to evaluate the strength and size of the double forwarder (DF) knot in 2 and 3 USP polyglactin 910 when used to form a ligature and to compare the knot holding capacity (KHC), size and weight of the DF knot to surgeon's (SU) and square (SQ) knots with varying numbers of throws.

STUDY DESIGN

Laboratory study.

STUDY POPULATION

Knotted suture.

METHODS

Knots were tied using 2 and 3 USP polyglactin 910 and tested on a universal testing machine under linear tension. Mode of failure and (KHC) were recorded. Knot volume and weight were determined by digital micrometer and balance. KHC, size, and weight between knot type, number of throws, and suture type and size were compared using ANOVA testing, with p < .05 as significant.

RESULTS

In both suture types, DF knots had a higher KHC than SQ/SU knots (p < .004), with the exception of SU knots with 6-8 throws in 3 USP polyglactin 910 (p > .42). All DF knots failed by suture breakage at the knot, as did all SQ/SU knots with >6 throws. DF knots in 2 and 3 USP polyglactin 910 were larger and heavier than SQ and SU knots when the same number of throws was applied (p < .003).

CONCLUSION

Self-locking DF knots provided increased strength compared to SU/SQ in large gauge suture but only when fewer than six throws are applied to SU/SQ knots.

CLINICAL RELEVANCE

The new DF knot could be an alternative for a secure ligature.

Early castration in foals: Consequences on physical and behavioural development

BACKGROUND

The impact of very early castration of foals has not yet been studied despite the many positive effects observed in dogs and cats.

OBJECTIVES

The objective of the study was to compare castration at 3 days and 18 months and assess their subsequent morphological and behavioural development.

STUDY DESIGN

This was a randomised, blinded clinical study.

METHODS

Twenty-two Welsh ponies underwent either early (3-day old, EC group, n = 11) or traditional (18-month old, TC group, n = 11) castration. Animals were followed up to 3 years of age. All ponies were castrated using a primary closure technique under general anaesthesia. Weight and morphometric measurements were monitored monthly from birth until 8 months of age in both groups. Then, measurements were taken every 3 months until 2 years of age and then every 6 months until 3 years of age. Temperament tests were performed on all animals when they were 1- and 3-years old.

RESULTS

No differences were observed between the EC and TC groups in terms of physical development from birth until 40 months of age or in terms of temperament and behaviour at either 1 or 3 years of age.

MAIN LIMITATIONS

The study included only one breed (Welsh ponies) and only 22 animals that were castrated before 2 years of age, precluding comparison with castration performed at older ages.

CONCLUSIONS

We demonstrate that early castration at 3 days does not interfere with morphological or behavioural development.

Evaluation of the subcapsular technique for primary closure castration in donkeys (Equus asinus)

This study described the subcapsular technique for primary closure castration in donkeys with special regard to its efficiency and welfare impacts. The study was conducted on twelve adult male donkeys, allocated randomly into two groups; subcapsular castration (SC) and open castration (OC) groups, whether the donkeys were subjected to surgical castration either by subcapsular or open castration techniques, respectively. Testosterone, cortisol, lactate, glucose, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), triglyceride (TG), and nitric oxide (NO) were measured before and after castration. Pain-associated behavioral activities were recorded post-castration. The SC was successfully performed in donkeys through a single paramedian scrotal incision. The SC was efficient as OC in reducing testosterone levels. The pain score decreased in the SC compared to the OC over time. The SC was an efficient and reliable technique for primary closure castration in donkeys with minimal postoperative complications and care and good cosmetic, physiological, and behavioral outcomes. It can be an alternative to other castration techniques in equines.

Inflammatory response of miniature horses subjected to open and half-closed orchiectomy techniques

BACKGROUND

This study aimed to evaluate the inflammatory response of miniature horses subjected to open and half-closed orchiectomy by physical examination, blood cell count, peritoneal fluid evaluation, total plasma protein, fibrinogen, and serum amyloid A (SAA) concentrations.

METHODS

Thirteen male healthy miniature horses were divided into two groups, according to the surgical approach: half-closed technique (HCT) and open technique (OT). The HCT group was subjected to ligation of the spermatic cord followed by its sharp incision, and closure of the vaginal tunic, and the OT group was only submitted to cord ligation. Prior to, and at 1, 2, 3 and 5 days after the surgery, a general and specific physical examination, blood cell counts, total plasma protein, peritoneal fluid evaluation, fibrinogen, and SAA concentrations were performed.

RESULTS

Higher postoperative perilesional oedema, rectal temperature, and fibrinogen were observed in the HCT group. Groups did not differ as to SAA concentrations. The evaluated local and systemic inflammatory profile demonstrated that, as expected, surgery resulted in inflammation in both groups.

CONCLUSIONS

The group subjected to the HCT showed a more intense and lasting inflammatory response. However, despite the different postoperative inflammatory profiles, both groups presented a favourable outcome and recovery.

Successful Surgical and Medical Management of a Pararectal Abscess in a Horse

Pararectal abscesses are life-threatening conditions that can rupture and cause septic peritonitis. The objective of this case report is to describe aggressive treatment of a pararectal abscess to allow a quick return to competitions. A 14-year-old pony was admitted to the Veterinary Teaching Hospital (VTH) of the University of Perugia because of a suspected intra-abdominal mass. Two weeks earlier, it exhibited clinical signs compatible with colic which was treated medically; however, because of the persistence of a firm mass on the right side of the abdomen noted on rectal palpation, the pony was admitted to the VTH. Based on rectal palpation, rectal ultrasound, neutrophilic leukocytosis, hyperfibrinogenemia, and elevated alkaline phosphatase, the diagnosis of a pararectal abscess was made. The horse was treated with ceftiofur IM and MgSO₄/paraffin oil via a nasogastric tube. Standing surgical drainage of the abscess with placement of an indwelling drain was performed, followed by daily lavages with rifampicin and acetylcysteine along with Ringer lactate solution with subsequent passive drainage. A bacterial culture revealed the presence of Streptococcus zooepidemicus that was treated with oral rifampicin. Standing laparoscopy revealed adhesions to the rectum. An epidural catheter was placed for repeated delivery of morphine sulfate. The pony was monitored daily by rectal examination, while complete blood count, fibrinogen, serum amyloid A, and abdominal ultrasound (to assess the size of the abscess) were repeated weekly. The pony progressively improved and was discharged one month later, shortly returning to competitions. This report emphasizes the importance of combining medical and surgical treatments for pararectal abscesses.

Surgical castration versus chemical castration in donkeys: response of stress, lipid profile and redox potential biomarkers

Background

Castration is a husbandry practice raising important questions on the welfare and physiological status of farm animals. Searching for effective castration methods that minimally compromise the body physiology is worthy of attention. Therefore, this study aimed to evaluate the differential response of biological systems in donkeys to surgical castration versus the chemical one by CaCl₂ with special emphasis on stress, lipid profile, and oxidative stress biomarkers. Donkeys were divided randomly and equally into two groups; the chemical (Ch) and surgical (S) groups (n = 6). The Ch group was chemically castrated by intratesticular injection of 20% CaCl₂ dissolved in absolute ethanol. Blood samples were collected prior to castration and at 15, 30, 45, and 60 days after the beginning of experiment.

Results

Surprisingly, the Ch group at the end of the experiment was characterized by significantly higher cortisol level compared to the S group. TC and LDL-C levels in the S group significantly decreased at day 45, while TG levels significantly increased at days 45 and 60 in comparison with day 0. HDL-C levels at days 30 and 60 in the Ch group significantly increased in comparison with day 0. At day 30 post-castration, HDL-C was significantly higher and LDL-C was significantly lower in the Ch group than the S group. A significant elevation in TC and LDL-C was observed at day 45 and in HDL-C at the end of experimental duration in the Ch group when compared with the S group. TPX level was significantly lower and TAC was significantly higher in the Ch group at day 45 than the S group.

Conclusion

Surgical castration evoked less stress and minor changes in lipid profile and oxidant/antioxidant balance relative to chemical castration by intratesticular 20% CaCl₂ dissolved in absolute ethanol.

Neuromas at the castration site in geldings

Background

Inguinal pain, unexplained hind limb lameness, back pain or behavioural problems in geldings could be attributable to painful neuromas that develop as a consequence of crushing and severing the testicular nerves during castration. The presence of neuroma in this anatomical location has never been reported, hence the knowledge of possible clinical relevance is limited. The aim of this study was to histologically investigate the testicular nerves at the castration site in geldings for the presence of neuromas. Proximal spermatic cord remnants were collected from 20 geldings admitted to routine post mortem examination for various reasons. The time of castration was unknown, but it had not been performed during the last year. Spermatic cord specimens were immersed in 10% formalin, trimmed, dehydrated, embedded in paraffin, sectioned and stained with haematoxylin and eosin (HE) for light microscopy. Identification of nerve tissue was done by immuno-localization of nerve specific enolase (NSE).

Results

Neuromas were found in 21 spermatic cords from 13 geldings and were bilateral in eight of the horses. The neuromas consisted of areas with small groups of non-neoplastic proliferations of peripheral neural tissue. The tissue included neurofilaments and Schwann cells, intermingled or surrounded with, epineural, perineural and endoneural fibrous tissue. The neural tissue immunostained positive with NSE.

Conclusions

This study showed neuromas of the remnant testicular nerves at the site of castration. Further studies are required to establish if these neuromas in the castration site are painful and if certain castration methods promote their formation. Future studies should also investigate the clinical consequence of these neuromas for the individual horse.

Pharmacokinetics of the anti-androgenic drug flutamide in healthy stallions

Alternatives to surgical castration are necessary for controlling the sexual behaviour of stallions with breeding potential in training and competition. Flutamide is a potent selective non-steroidal androgen receptor competitive antagonist that has been used in human beings as an anti-androgenic drug. In this study, the pharmacokinetics and bioavailability of flutamide and its main active metabolite, 2-hydroflutamide, were determined in seven healthy mature stallions. Single doses of flutamide (1mg/kg intravenously, 1mg/kg orally in fasted horses, 5mg/kg orally in fasted horses and 5mg/kg orally in fed horses) were administered randomly at intervals of 2 weeks. All horses had full physical examinations and blood samples were collected for pharmacokinetics, complete blood counts and biochemistry before and after drug administration. Administration of flutamide did not result in any abnormalities on physical examination or in blood parameters. After intravenous administration of flutamide, the volume of distribution was 0.83L/kg and clearance was 1.20L/h/kg. Flutamide and its metabolite had high protein binding values (93-97%). After oral administration, flutamide was rapidly transformed to 2-hydroxyflutamide, with areas under the concentration-time curve ratios of metabolite:drug ∼7. Oral bioavailability was 6.63% after 1mg/kg flutamide in fasted horses, 6.50% after 5mg/kg flutamide in fasted horses and 6.95% after 5mg/kg in fed horses. Half lives of flutamide were close to 1h after intravenous administration and 2h after oral administration. Half lives of 2-hydroxyflutamide were 4.79-6.84h for all routes and doses. After oral administration, oral flutamide reached plasma concentrations that could be effective as an anti-androgenic agent in horses, but further studies are needed to determine whether flutamide has clinical value as an alternative to castration for controlling sexual behaviour in stallions.