Evaluation of common vaginal tunic ligation during field castration in draught colts

The objective of this study was to determine if ligation of the common vaginal tunic could prevent or reduce the incidence of omental herniation and eventration in draught colts undergoing routine field castration. It was found that common vaginal tunic ligation, while not completely preventing omental herniation and evisceration, significantly reduced the incidence of these complications and should be considered in those males deemed at increased risk of significant post castration complications.     

Changes in the EEG during castration in horses and ponies anaesthetized with halothane

Objective To identify changes in the amplitude spectrum of the electroencephalogram (EEG) during a standardized surgical model of nociception in horses. Animals Thirteen entire male horses and ponies referred to Division of Clinical Veterinary Science, Bristol (n = 9) and Department of Clinical Veterinary Medicine (n = 4) for castration. Materials and methods Following pre‐anaesthetic medication with acepromazine, anaesthesia was induced with guaiphenesin and thiopental and maintained with halothane in oxygen. The EEG was recorded continuously using subcutaneous needle electrodes. Additional monitoring comprised ECG, arterial blood pressure, blood gas analysis, airway gases, and body temperature. All animals were castrated using a closed technique. The raw EEG was analysed after completion of each investigation and the EEG variables median frequency (F50), spectral edge frequency (SEF) 95% and total amplitude were derived from the spectra using standard techniques. The mean values of EEG variables recorded during a baseline time period (recorded before the start of surgery) and castration of each testicle were compared using analysis of variance for repeated measures. Results Total amplitude (Atot) decreased and F50 increased during castration of each testicle compared to the baseline time period [(89.0 ± 7.8% testicle 1, 87.0 ± 7.8% testicle 2) and (110.0 ± 15.0% testicle 1, 109.0 ± 15.0% testicle 2), respectively]. Changes in SEF 95% were not significant. Conclusions De‐synchronization was identified in the EEG during the nociceptive stimulus of castration. The results suggest that an increase in F50 may be a specific marker for nociception in the horse. Clinical relevance Studies investigating the efficacy of analgesic agents in horses are limited by difficulties in peri‐operative pain assessment. This model, using EEG changes associated with nociceptive stimulation, can be used to investigate the anti‐nociceptive efficacy of different anaesthetic agents in the horse.     

Comparison of the use of a braided multifilament transfixation suture for field castration with other castration techniques

Complications with castrations occur commonly and are usually not life-threatening, with the exception of evisceration or haemorrhage, which are uncommon. Primary closure castration (closing deeper tissue layers and skin) or use of a transfixation ligature alone to prevent evisceration has been recommended. The goal of this study was to investigate the use of a closed technique with multifilament suture for transfixation of the spermatic cord alone in field castrations. The results of this study support our hypothesis that a closed castration technique with a multifilament, transfixing ligature (No. 2 polyglactin 910) did not result in additional post-operative complications when compared with a closed castration technique without ligature placement or a primary closure castration technique in a hospital setting.     

Herniation of the small intestine through the femoral canal after castration in a 3‐year‐old Thoroughbred

Complications following castration are a potential problem in equine practice. Intestinal evisceration is a life‐threatening condition requiring immediate correction. The following case report describes a rare condition associated with post castration evisceration in a 3‐year‐old Thoroughbred. Shortly after the eviscerated small intestine was repositioned in the abdomen, the horse showed signs of colic and at the second surgery a 4.5 m jejunal loop was found incarcerated in the femoral canal. After resection and anastomosis, the femoral canal was obliterated using large moistened gauze sponges. The horse made a complete recovery and returned to race training. The occurrence of femoral hernia, a condition fairly common in man, has been described but no clinical cases have been reported in horses. This is a severe, although rare, complication after castration.     

Short‐term anaesthesia with xylazine,diazepam/ketamine for castration in horses under field conditions: Use of intravenous lidocaine

Reasons for performing study: Lidocaine single boluses and/or constant rate infusions are commonly administered intraoperatively during inhalant anaesthesia to lower inhalant concentrations, promote or maintain gastrointestinal motility, and potentially supplement analgesia. The benefits of using lidocaine with injectable anaesthesia for field surgeries has not been fully explored to determine advantages and disadvantages of lidocaine as an anaesthetic and analgesic adjunct in these conditions and impact on recovery quality. Objectives: To evaluate the use of systemic lidocaine with a standard field injectable anaesthetic protocol related to the need for additional drug administration as well as overall recovery score and quality. Hypothesis: The administration of systemic lidocaine with xylazine‐diazepam/ketamine anaesthesia for castration in the field decreases the need for additional injectable doses required for maintenance, but prolong and potentially impact the overall recovery score and quality in horses. Methods: Thirty client‐owned horses underwent standard injectable anaesthesia for field castration. Fifteen horses received lidocaine 3 mg/kg bwt, i.v. as a single bolus, and 15 received saline equal volume. The horses were monitored for the need for additional injectable anaesthetics and scored for overall recovery and quality by a blinded anaesthetist. Results: There were no statistically significant differences in the overall recovery score and quality, or need for additional injectable anaesthetic between horses receiving lidocaine and those receiving saline. There was a significantly longer time for the horses to stand after induction in the lidocaine group (mean 30.7 min) vs. saline group (mean 22.5 min) (P<0.04). Conclusions: Lidocaine, 3 mg/kg bwt i.v., does not adversely affect recovery using injectable field regimes, but the overall recovery period was longer. Lidocaine does not appear to reduce the need for additional injectable administration during surgery. Potential relevance: Further research is warranted to define the benefit of systemic lidocaine with field anaesthesia in horses by exploring the ideal dose and plasma level of lidocaine with injectable anaesthesia.     

Comparison of post-operative inflammatory response in horses undergoing elective castration treated preoperatively with ceftiofur crystalline free acid or procaine penicillin G

Castration is among the most common surgical procedures performed in the horse (Equus Caballus) and a variety of post-operative complications can occur. This study aims to determine if a single dose of long-acting ceftiofur crystalline free acid (CCFA) used as a preoperative antimicrobial in equine field castrations offers any reduction in post-operative inflammatory markers when compared to procaine penicillin G (PPG). Sixty-five horses aged 8 months to 2 years were randomly assigned to the CCFA (n = 33) or PPG (n = 32) treatment groups. Horses were castrated under general anaesthesia using a closed castration technique with removal of the median raphe. Quantitative and qualitative inflammatory markers were measured and short-term complications were recorded post-operatively on Days 3, 8 and 14. No clinically significant difference in any post-operative inflammatory markers between the CCFA and PPG group was detected. In the CCFA group, 48% of horses experienced short-term post-operative complications compared to 31% in the PPG group. Regardless of the preoperative treatment, castration induced significant elevation in serum amyloid A (P<0.0001), preputial oedema (P<0.0001) and scrotal oedema (P<0.0001) at Day 3. These values returned to baseline levels by Day 8. Horses with grade 3 or above preputial oedema had elevated serum amyloid A values (P<0.001). The data from this study indicate CCFA used as a preoperative antibiotic for routine castration offers no advantages over PPG. The difference in complication rate between groups is likely of minimal clinical importance, as all complications were mild and self-limiting.     

Equine castration: review of anatomy, approaches, techniques and complications in normal, cryptorchid and monorchid horses

Complications associated with equine castration are the most common cause of malpractice claims against equine practitioners in North America. An understanding of the embryological development and surgical anatomy is essential to differentiate abnormal from normal structures and to minimise complications. Castration of the normal horse can be performed using sedation and regional anaesthesia while the horse is standing, or under general anaesthesia when it is recumbent. Castration of cryptorchid horses is best performed under general anaesthesia at a surgical facility. Techniques for castration include open, closed and half-closed techniques. Failure of left and right testicles to descend occurs with nearly equal frequency, however, the left testicle is found in the abdomen in 75% of cryptorchid horses compared to 42% of right testicles. Bilateral cryptorchid and monorchid horses are uncommon. Surgical approaches described for the castration of cryptorchid horses include an inguinal approach with or without retrieval of the scrotal ligament, a parainguinal approach, or less commonly a suprapubic paramedian or flank approach. Laparoscopic castration of cryptorchid horses has recently been described but the technique has limited application in practice at this time. A definitive diagnosis of monorchidism can only be made after surgical exploration of the abdomen, removal of the normal testis and hormonal testing. Hormonal assays reported to be useful include analysis of basal plasma or serum testosterone or oestrone sulphate concentrations, testosterone concentrations following hCG stimulation, and faecal oestrone sulphate concentrations. Reported complications of castration include postoperative swelling, excessive haemorrhage, eventration, funiculitis, peritonitis, hydrocele, penile damage and continued stallion-like behaviour.     

Acute cortisol responses and wound healing in lambs after ring castration plus docking with or without application of a castration clamp to the scrotum

OBJECTIVE: To test whether the cortisol response to ring castration plus docking is reduced by additional application of a castration clamp across the full width of the scrotum distal to the ring. DESIGN: A physiological study with controls. PROCEDURE: Lambs, 3 to 6 weeks of age, were castrated using a ring or ring plus castration clamp applied for 6 or 10 s and docked using a ring. Blood samples were taken before and regularly for about 4 h after treatment and analysed for plasma cortisol concentrations. The healing of the scrotal wounds was monitored for 6 weeks after castration. RESULTS: The plasma cortisol concentrations were lower only at 60 min after treatment in lambs castrated with a clamp placed on the scrotum for 10 s after ring castration and docking than in lambs castrated and docked by ring alone. Scrotal wounds healed more quickly after ring plus clamp than after ring only castration. CONCLUSIONS: The castration clamp had at most a marginal effect on the cortisol response to ring castration and docking of 3- to 6-week-old lambs, but it did seem to improve the rate of healing.     

Evaluation of a pinhole castration technique in ponies: Comparing single with double ligation (using silk or catgut) of the spermatic cord

The objective of the study was to evaluate a pinhole castration technique in male ponies. Adult ponies (n = 12) were randomly allotted to one of the two equal groups. Both of the groups were anaesthetised with xylazine–ketamine–diazepam and had single (SLS, SLC) ligation of the spermatic cord on one side and double (DLS, DLC) ligation on the other side using silk (Group T1) and catgut (Group T2). Single ligation whether using silk or catgut (SLS and SLC) was completed in 3.50 ± 0.34 min. DLS took 6.66 ± 0.49 min and DLC 7.16 ± 0.47 min. Scrotal oedema was noticed in all of the ponies from Day 1 to Day 15. The scrotal circumference and testicular volume in animals of both of the groups showed a significant (P<0.05) increase from Day 1 to Day 4. Orchiectomy to recover testicular remnants was performed in all of the animals on Day 41. Straw-coloured fluid accumulation was noticed in seven testicular remnants (4 T1 and 3 T2). One testicle from Group DLS showed suppuration. Multiple gross and histological abnormalities were detected in all double ligated testes. The changes were more severe in the DLS than the DLC group and their epididymis (n = 3) also showed necrosis, fibroplasia and an obstructed lumen. Severe adhesions had developed in three and one testicle only from the SLS and SLC groups respectively. The remaining testes and epididymis in both of these groups showed only mild-to-moderate adhesions. From this study, it was concluded that castration may not be achieved by percutaneous single ligation of the spermatic cord in ponies. Although double ligation induces marked gross and histopathological changes, assessments of the testosterone levels and sperm analysis are required before recommending this procedure. Use of silk for ligation of the spermatic cord is advantageous over catgut but maintenance of strict asepsis is mandatory.     

An acellular aortic matrix of buffalo origin crosslinked with 1‐ethyl‐3‐3‐dimethylaminopropylcarbodiimide hydrochloride for the repair of inguinal hernia in horses

An acellular aortic matrix (AAM) crosslinked with 1‐ethyl‐3‐3‐dimethylaminopropylcarbodiimide hydrochloride (EDC) was evaluated for the repair of inguinal hernias in 5 horses. The aorta from buffalo was acellularised using 1% sodium dodecyl sulfate (SDS) and 0.25% trypsin. The AAM was crosslinked with 1% EDC. Under anaesthesia, inguinal hernias were repaired with EDC‐crosslinked AAM graft using an inlay graft technique. Blood samples collected on Days 0, 15 and 30 post implantation, were used for SDS polyacrylamide gel electrophoresis (PAGE) analysis to assess the animals' serum protein concentration, and gelatin zymography for the identification of matrix metalloproteinases. All animals that underwent hernia repair demonstrated successful healing without clinical signs of wound dehiscence, infection or recurrence during a 6‐month follow‐up period. SDS‐PAGE analysis of serum protein concentrations revealed that, this was increased at Day 15 and had decreased again at Day 30. Gelatin zymography of serum of implanted horses expressed a band of 92 kDa, corresponding to MMP‐9 activity. The relative amount of the 92 kDa band was higher at Day 15 as compared to Days 0 and 30. It may be concluded that EDC‐crosslinked AAM of buffalo origin can be used safely in horses for the repair of inguinal hernia with adequate strength and minimal foreign body reaction.     

Effects of abdominocentesis technique on peritoneal fluid and clinical variables in horses

Eleven healthy horses underwent 5 repeated abdominocenteses, with either a sharp‐tipped spinal needle or a blunt‐tipped teat cannula to investigate possible differences in success rate, sample volume, depth at which a sample was obtained, length of procedure, complications and cytological variables. Variables were analysed with a repeated‐measures ANOVA or Fisher's exact test (α = 0.05). Success rate, sample volume, length of procedure, occurrence of haemorrhage during the procedure and incidence of grossly visible blood contamination were not different between techniques or over time. Depth at which samples were obtained was greater using a cannula than a needle (P<0.02), and samples were obtained with either technique at a greater depth than abdominal wall thickness assessed via ultrasound (P<0.014). Peritoneal fluid total and differential nucleated cell counts, and total protein concentration did not differ between techniques or over time. Red blood cell count in the least blood contaminated fraction of each sample was not affected by time, but it was lower after needle abdominocentesis than after cannula abdominocentesis (P = 0.04). Swelling of abdominocentesis sites increased with both techniques over time (P<0.05) and was more severe in horses undergoing cannula abdominocentesis (P<0.05). Enterocentesis occurred with a spinal needle in one horse, but no subsequent complications were noted. Both techniques appear to be safe and reliable for abdominocentesis in healthy horses. Using a blunt‐tipped cannula, as opposed to a needle, is likely to result in greater subcutaneous swelling. Both the cannula and needle must be long enough to penetrate well beyond the thickness of the abdominal wall to achieve successful peritoneal fluid collection.     

Tunnel grafting for wound repair in horses: a novel technique in graft production and placement

There are several skin grafting methods described in the human and animal literature. Currently, there are five types of free grafts used in horses: pinch and punch grafts, split and full-thickness sheet or mesh grafts and tunnel grafts. Published methods of tunnel grafting describe the use of alligator forceps. The alligator forceps create a poor tunnel and are excessively traumatic to the granulation bed. This technique utilised a 13G Jamshidi needle that was placed across the granulation bed and created a uniform tunnel. The Jamshidi needle was atraumatic to the granulation bed increasing the opportunity for graft survival. A twin bladed scalpel allowed for the quick creation of uniform width grafts. Removal of the overlying tunnel ‘roof’ took place 5–14 days later to allow graft expansion. This case series included five horses with distal limb wounds and one with a wither injury. Four horses required general anaesthesia for graft placement and three required general anaesthesia for the removal of the tunnel roof. The acceptance of the grafts varied from 70% to 100%. Graft expansion to cover the granulation tissue took 2–5 months. This case series demonstrates that this technique of graft production and placement is an easy method for achieving successful skin grafting. Compared to other graft types, tunnel grafts are more readily accepted. Cosmetic and functional results achieved are better than those with pinch and punch grafts. Tunnel grafting does not require expensive equipment or advanced training, and in some cases can be performed under standing sedation.     

Clinical and pharmacokinetic evaluation of S-ketamine for intravenous general anaesthesia in horses undergoing field castration

Background

Intravenous anaesthetic drugs are the primary means for producing general anaesthesia in equine practice. The ideal drug for intravenous anaesthesia has high reliability and pharmacokinetic properties indicating short elimination and lack of accumulation when administered for prolonged periods. Induction of general anaesthesia with racemic ketamine preceded by profound sedation has already an established place in the equine field anaesthesia. Due to potential advantages over racemic ketamine, S-ketamine has been employed in horses to induce general anaesthesia, but its optimal dose remains under investigation. The objective of this study was to evaluate whether 2.5 mg/kg S-ketamine could be used as a single intravenous bolus to provide short-term surgical anaesthesia in colts undergoing surgical castration, and to report its pharmacokinetic profile.

Results

After premedication with romifidine and L-methadone, the combination of S-ketamine and diazepam allowed reaching surgical anaesthesia in the 28 colts. Induction of anaesthesia as well as recovery were good to excellent in the majority (n = 22 and 24, respectively) of the colts. Seven horses required additional administration of S-ketamine to prolong the duration of surgical anaesthesia. Redosing did not compromise recovery quality. Plasma concentration of S-ketamine decreased rapidly after administration, following a two-compartmental model, leading to the hypothesis of a consistent unchanged elimination of the parent compound into the urine beside its conversion to S-norketamine. The observed plasma concentrations of S-ketamine at the time of first movement were various and did not support the definition of a clear cut-off value to predict the termination of the drug effect.

Conclusions

The administration of 2.5 mg/kg IV S-ketamine after adequate premedication provided good quality of induction and recovery and a duration of action similar to what has been reported for racemic ketamine at the dose of 2.2 mg/kg. Until further investigations will be provided, close monitoring to adapt drug delivery is mandatory, particularly once the first 10 minutes after injection are elapsed. Taking into account rapid elimination of S-ketamine, significant inter-individual variability and rapid loss of effect over a narrow range of concentrations a sudden return of consciousness has to be foreseen.     

Management and complications associated with treatment of cervical oesophageal perforations in horses

Six horses were evaluated for colic and anorexia, choke or suspected oesophageal rupture with and without tracheal laceration. Clinical findings were variable, but a painful ventral neck swelling was noted in all cases. Two of the horses had signs of dehydration and sepsis. Additional findings included evidence of previous trauma over the trachea and oesophagus, ventral neck abscessation, choke and aspiration pneumonia. A diagnosis of oesophageal perforation was made using endoscopy. Two horses were subjected to euthanasia without treatment. All horses where treatment was attempted received debridement of the oesophageal perforation and surrounding tissues with or without surgical closure of the oesophageal defect. Other therapies included broad spectrum antimicrobials, anti‐inflammatory drugs, fluid and nutritional support as well as additional therapeutics for sepsis and individual complications. Complications included diverticulum formation, thrombophlebitis, diarrhoea, laryngeal hemiplegia, azotaemia, aspiration pneumonia, oesophageal obstruction, weight loss and laminitis. All 4 treated horses recovered from the oesophageal perforation and are able to eat a normal diet. Two of the 4 horses have had infrequent episodes of recurrent choke. Oesophageal rupture should be considered as a differential diagnosis for horses with a painful swelling of the ventral neck. With surgical debridement and adequate supportive care, oesophageal perforation cases can have a fair to good long‐term survival, although chronic complications can occur, therapy is prolonged, and a significant economic commitment is required.     

Parainguinal laparotomy as an alternative surgical approach for removal of an enterolith in the small colon of a horse

This report describes the use of a parainguinal approach to the abdomen to remove an obstruction in the small colon that could not be removed using an initial ventral midline approach. The use of a parainguinal approach should be considered for removal of an obstruction in the distal portion of the small colon.     

Validation of a transendoscopic glandular and nonglandular gastric biopsy technique in horses

Reasons for performing study: In order to study the evolution of histopathological and immunohistochemical changes in the gastric mucosa of horses with EGUS (equine gastric ulcer syndrome), a feasible, useful, valid and safe in vivo gastric biopsy technique is required. Objectives: To determine the average gastric mucosal healing time following endoscopic gastric biopsy sampling, and evaluate the feasibility, safety and usefulness of samples obtained by this method for histopathological analysis. Methods: Six mature mares from the Faculté de Médecine Vétérinaire research herd were used. Transendoscopic gastric biopsy was performed on Days 0 and 9 using a flexible forceps with oval and fenestrated jaws to obtain gastric mucosal samples from 4 different sites: cardia (C), fundus (F), margo plicatus (MP) and glandular mucosa (GL). A maximum of 4 samples per site was taken and processed routinely for histopathology, evaluated by a pathologist. On Days 1–4 and 9–11 the lesions created by the biopsies were evaluated by gastroscopy. Lesions were evaluated over time based on a score from 0–4, where 4 was the most severe. Results: Biopsy samples could be obtained from all targeted sites except C. No abnormal clinical signs were observed up to 7 days post biopsy. The average biopsy lesion scores decreased significantly with time for all sites. The average lesion score was significantly higher for the MP compared to the other sites at Days 1 and 2. Samples taken from the nonglandular portion of the stomach were considered inadequate for histopathology, while those taken from the glandular mucosa were adequate. Conclusion: The transendoscopic gastric biopsy technique described here is a feasible, safe and useful technique for obtaining samples from the equine gastric glandular mucosa. Although biopsy samples could be obtained from several areas in the nonglandular mucosa, these were very small, took longer to heal and were not considered adequate for histopathological evaluation, and another technique should therefore be validated.     

Performance and rideability issues in horses as a manifestation of pain: A review of differential diagnosis and diagnostic approach

Nonspecific performance and rideability issues are more likely a manifestation of pain in the ridden horse rather than a true behavioural problem. A systematic and thorough investigation focusing on the potential presence of pain-related conditions is thus crucial in horses with such complaints. It can, however, be challenging to determine whether the complaint is indeed related to pain, where the pain is located, and what the underlying cause is. This review describes the challenges of pain recognition in ridden horses and summarises the recently developed ridden horse ethograms that might enable pain to be assessed in an objective, valid and reliable way. Furthermore, the differential diagnosis and diagnostic approach to horses presenting potentially pain-related performance and rideability issues are discussed.