Retrospective analysis of detomidine infusion for standing chemical restraint in 51 horses

Objective To assess the effectiveness of a detomidine infusion technique to provide standing chemical restraint in the horse. Design Retrospective study. Animals Fifty‐one adult horses aged 9.5 ± 6.9 years (range 1–23 years) and weighing 575 ± 290.3 kg. Methods Records of horses presented to our clinic over a 3‐year period in which a detomidine infusion was used to provide standing chemical restraint were reviewed. Information relating to the types of procedure performed, duration of infusion, drug dosages and adjunct drugs administered was retrieved. Results Detomidine was administered as an initial bolus loading dose (mean ± SD) of 7.5 ± 1.87 µg kg^?1. The initial infusion rate was 0.6 µg kg^?1 minute^?1, and this was halved every 15 minutes. The duration of the infusion ranged from 20 to 135 minutes. Twenty horses received additional detomidine or butorphanol during the procedure. All horses undergoing surgery received local anesthesia or epidural analgesia in addition to the detomidine infusion. A wide variety of procedures were performed in these horses. Conclusions Detomidine administered by infusion provides prolonged periods of chemical restraint in standing horses. Supplemental sedatives or analgesics may be needed in horses undergoing surgery. Clinical relevance An effective method that provides prolonged periods of chemical restraint in standing horses is described. The infusion alone did not provide sufficient analgesia for surgery and a significant proportion of animals required supplemental sedatives and analgesics.     

The use of computed tomography to assist orthopaedic surgery in 86 horses (2002–2010)

Imaging‐assisted orthopaedic surgery is becoming part of routine orthopaedic practice in horses and several techniques have been reported. However, there are no published reports describing the use of intraoperative computed tomography (CT) for surgical guidance and immediate post operative control in the horse. This use of CT in equine orthopaedics is currently limited because of the logistic problems associated with availability of CT scans in surgical theatres as well as concerns over radiation safety. The aim of this report was retrospectively to report CT assisted orthopaedic surgical cases in our practice through identifying the types of surgery where it was used, to list the technical problems that were encountered, to describe solutions to these, and to discuss the applications of the technique. All surgical procedures were performed with the assistance of a peripheral quantitative computed tomography (pQCT) scanner. CT assisted orthopaedic surgery in 86 patients during the study period. Reasons for CT included: 1) use of CT at the beginning of the surgical procedure to document the lesion and identify surgical landmarks (n = 75); 2) pre, intra‐ and post operative use of CT in comminuted fractures of the middle or proximal phalanx to guide and control internal fixation (n = 7); and 3) post operative use of CT to monitor the results of the surgical procedure (n = 4). Proper planning in both the draping steps and the use of polyvinyl splints to stabilise the limb allowed for movements of the gantry around the limb. The time required to obtain one slice was not dissimilar to the time that is necessary to take and process a single digital radiograph. The radiation dose with the pQCT described here is <0.5 µSv and its acquisition time should be balanced against radiation risks of conventional CT systems.     

Complications associated with transurethral endoscopic‐assisted electrohydraulic lithotripsy for treatment of a bladder calculus in a gelding

A cystic calculus approximately 6 cm in diameter was diagnosed by ultrasonography and endoscopy in a 12‐year‐old Trakehner gelding with a history of haematuria and dysuria. Transurethral endoscopic lithotripsy with electrohydraulic shock waves was performed as a minimally invasive treatment option. Fragmentation of the calculus was achieved, the fragments of the calculus left in the bladder and excretion assisted by infusion of Ringer's solution. Twenty‐four hours after the third lithotripsy, the horse suffered a recurrence of dysuria and pollakiuria due to partial obstruction of the urethra by the calculus fragments. The treatment was repeated within the urethra until clearance of the fragments was achieved. The sharp fragments had produced a zone of urethral mucosal trauma, approximately 10 cm in length. At the follow‐up visit 4 weeks later, the patient had developed inflammation and swelling of the urethral mucosa, which was successfully treated with a 14 day course of anti‐inflammatory drugs. This resulted in normal urination. At the last follow‐up, the horse had been recurrence‐free for 12 months.     

Return to use and performance following exploratory celiotomy for colic in horses: 195 cases (2003–2010)

Reasons for performing study: There are few objective data on return to use and performance in horses following colic surgery. Objective: To investigate return to functional use of horses following colic surgery and factors associated with a negative outcome. Methods: The North Carolina State University Equine Colic Database was reviewed for horses that underwent exploratory celiotomy for colic (2003–2010). Horses were excluded from the study if they survived <6 months, had no intended use preoperatively, or if further data were not available at attempted follow‐up. Information retrieved included history, background, use, and selected pre‐, intra‐, and post operative factors. Telephone interviews were used to obtain follow‐up data. Logistic regression was used to investigate associations between clinical data and outcome, reported as odds ratios with a 95% confidence interval and corresponding P value. Results: Of patients surviving to 6 months, 133/195 (68%) were performing their intended use and 85/156 (54%) were at or above preoperative performance. At one year, 145/190 (76%) horses were performing their intended use and 101/153 (66%) were at or above preoperative performance. Animals were significantly less likely to return to use/performance if they had a previous celiotomy, stall rest for an orthopaedic condition, a nonstrangulating lesion type, incisional hernia, diarrhoea or laminitis. Conclusions: The overall prognosis for return to use and performance following colic surgery is fair to good. Multiple pre‐ and post operative factors may affect the likelihood of return to use and performance. Potential relevance: Targeted owner education regarding preoperative lameness, post operative rehabilitation and treatment for complications, such as incisional hernioplasty, may help inform owners about their horse's potential for return to use and performance following colic surgery.     

Standing hand‐assisted laparoscopic removal of large granulosa cell tumours in horses using a specimen retrieval bag and morcellator

This report describes a method for removal of large granulosa cell tumours through small paralumbar incisions using laparoscopic dissection of the mesovarium and subsequent removal of the ovary in a sterile retrieval bag via morcellation. Morcellation allows division of the granulosa cell tumour and subsequent reduction of incision size required for removal. The use of a specimen retrieval bag prevented contamination of the abdomen and incision with tumour cells during activation of the morcellator.     

The use of porcine urinary bladder matrix (UBM) to repair a perforated corneal ulcer with iris prolapse in a horse

This report describes the use of porcine urinary bladder matrix (UBM) to repair a full thickness defect in the cornea of a Thoroughbred racehorse. The horse presented with acute keratomalacia of the right eye of 12 h duration that had rapidly progressed to perforation of the cornea with partial iris prolapse. The cornea was surgically debrided with the horse under general anaesthesia and the defect repaired with ACell multilayer wound matrix. A temporary tarsorrhaphy was performed. The defect in the cornea was successfully repaired and the horse regained vision in the eye. Four months after surgery the defect was still undergoing remodelling and the area of opacity in the cornea was progressively reducing.     

Hormonal, metabolic and physiological effects of laparoscopic surgery using a detomidine-buprenorphine combination in standing horses

Objective To assess the hormonal, metabolic and physiological effects of laparascopic surgery performed under a sedative analgesic combination of detomidine and buprenorphine in standing horses. Study design Prospective study. Animals Eight healthy adult Dutch Warmblood horses and five healthy adult ponies undergoing laparoscopy were studied. Five healthy adult horses not undergoing laparoscopy were used as a control group. Methods The sedative effect of an initial detomidine and buprenorphine injection was maintained using a continuous infusion of detomidine alone. The heart and respiratory rate, arterial blood pH and arterial oxygen and carbon dioxide tensions were monitored, while blood samples were taken for the measurement of glucose, lactate, cortisol, insulin and nonesterified fatty acids (NEFA). The same variables were monitored in a control group of horses which were sedated, but which did not undergo surgery. At the end of the sedation period the effects of detomidine were antagonized using atipamezole. Results The protocol provided suitable conditions for standing laparoscopy in horses. Laparoscopy induced obvious metabolic and endocrine responses which, with the exception of NEFA values, were not significantly different from changes found in the control group. While atipamezole did not produce detectable adverse effects, it is possible that anatagonism may not be essential. Conclusions The technique described reliably produces adequate sedation and analgesia for laparoscopic procedures. The level of sedation/analgesia was controlled by decreasing or increasing the infusion rate. Antagonism of the effects of detomidine may not be necessary in all cases.     

Evaluation of a romifidine constant rate infusion protocol with or without butorphanol for dentistry and ophthalmologic procedures in standing horses

ObjectiveTo compare the clinical usefulness of constant rate infusion (CRI) protocols of romifidine with or without butorphanol for sedation of horses.Study designProspective ‘blinded’ controlled trial using block randomization.AnimalsForty healthy Freiberger stallions.MethodsThe horses received either intravenous (IV) romifidine (loading dose: 80 μg kg^?1; infusion: 30 μg kg^?1 hour^?1) (treatment R, n = 20) or romifidine combined with butorphanol (romifidine loading: 80 μg kg^?1; infusion: 29 μg kg^?1 hour^?1, and butorphanol loading: 18 μg kg^?1; infusion: 25 μg kg^?1 hour^?1) (treatment RB, n = 20). Twenty-one horses underwent dentistry and ophthalmic procedures, while 19 horses underwent only ophthalmologic procedure and buccal examination. During the procedure, physiologic parameters and occurrence of head/muzzle shaking or twitching and forward movement were recorded. Whenever sedation was insufficient, additional romifidine (20 μg kg^?1) was administered IV. Recovery time was evaluated by assessing head height above ground. At the end of the procedure, overall quality of sedation for the procedure was scored by the dentist and anaesthetist using a visual analogue scale. Statistical analyses used two-way anova or linear mixed models as relevant.ResultsSedation quality scores as assessed by the anaesthetist were R: median 7.55, range: 4.9–9.0 cm, RB: 8.8, 4.7–10.0 cm, and by the dentist R: 6.6, 3.0–8.2 cm, RB: 7.9, 6.6–8.8 cm. Horses receiving RB showed clinically more effective sedation as demonstrated by fewer poor scores and a tendency to reduced additional drug requirements. More horses showed forward movement and head shaking in treatment RB than treatment R. Three horses (two RB, one R) had symptoms of colic following sedation.Conclusions and clinical relevanceThe described protocols provide effective sedation under clinical conditions but for dentistry procedures, the addition of butorphanol is advantageous.     

The use of intraluminal stents for tracheal collapse in two horses: Case management and long‐term treatment

Tracheal collapse is an uncommon clinical disorder in horses but when present can be difficult to correct. Various medical and surgical procedures to correct tracheal collapse have been described in horses with variable success. Recently, the use of an intraluminal stent has been described as a treatment for tracheal collapse in a miniature horse. The long‐term management, utilising intraluminal stents, in 2 miniature horses with tracheal collapse is presented here. In particular, various complications as a result of intraluminal stent placement are described, the most persistent being the formation of granulation tissue at various regions of the stents. Multiple methods of combating granulation tissue in this situation also are discussed.     

Heterotopic polydontia as a cause for a cystic lesion in the paranasal sinus of a Thoroughbred filly

A 1-year-old Thoroughbred filly with left bony facial distortion was diagnosed with a multilobar expansile mass within the caudal maxillary and frontal sinuses on computed tomography (CT). Typical findings associated with a sinus cyst, including expression of amber fluid from the mass and a thick lining that could be peeled from the sinus walls, were found on surgical exploration of the sinus under general anaesthesia. Histological examination of firm structures within the fluid-filled cyst contained all components of embryologically normal dental tissue. The filly recovered well and entered training to race as a 2-year-old, as remodelling of the bony distortion and narrowing of the nasal passage was sufficient for airflow. Previous reports of paranasal cystic lesions in horses suggest developmental abnormalities as a causative factor, especially in young horses. Furthermore, heterotopic polydontia is reported as the underlying aetiology in some human paranasal sinus cysts. While polydontia has been reported in the paranasal sinuses and nasal passages of horses, this is the first case report that finds them associated with a cystic lesion within the paranasal sinus.     

Contemporary use of acepromazine in the anaesthetic management of male horses and ponies: a retrospective study and opinion poll

Reason for performing study: Current use of acepromazine in the anaesthetic management of male horses and ponies and associated risks are largely unknown. Objectives: To explore anaesthetic acepromazine use and related adverse effects in the male horse. Methods: Of 8533 anaesthetised horses and ponies medical records of male animals treated perianaesthetically with acepromazine were reviewed. Demographic data, time and dose of acepromazine administration, co‐administered drugs, quality of induction and recovery from anaesthesia, arterial blood pressures, and occurrence of penile dysfunction were recorded. Practising ACVA and ECVAA diplomates were polled on the use of acepromazine and its effects on blood pressure and penile dysfunction in the equine. Results: Of all animals, 12% females and 11% males (n = 575 including 42% stallions) received perianaesthetic acepromazine, predominantly for premedication. Anaesthetic induction was smooth in 566 animals. Lowest mean arterial pressures averaged 65 ± 9 mmHg. Recovery was good or very good in 70% of all animals and 74% stood after 1–2 attempts. In 14 horses (2.4%; 7 stallions, 7 geldings), penile prolapse occurred for 0.5–4 h and in one stallion (0.2%) for >12 but <18 h post recovery. Most surveyed anaesthesiologists use acepromazine in stallions (occasionally 63%; frequently 17%) but more frequently in geldings (occasionally 34%; frequently 59%) and mares (occasionally 38%; frequently 59%), primarily for premedication with other sedatives and analgesics. Persistent intraoperative hypotension was not frequently reported. Only 5% of surveyed anaesthesiologists recall penile prolapse post acepromazine administration lasting for >12 h and only one recalls 3 cases of irreversible penile prolapse in 20 years of anaesthesia practice. Conclusions and potential relevance: The extremely low risk of permanent penile dysfunction (≤1 in 10,000 cases) does not justify more restricted use of acepromazine in the intact male vs. geldings and mares.     

Evaluation of the use of an endotracheal tube as a novel method of short-term haemostasis in post-operative paranasal sinus surgery in three horses

This case series describes placement of an endotracheal tube (ETT) with an air-inflated cuff within surgically created sinonasal windows as a technique of post-operative haemostasis. A frontonasal bone flap and a sinonasal window were performed routinely in three standing horses with paranasal sinus disease. In Case 1, the fistula was initially gauze packed, which controlled haemorrhage until concerns of gauze dislodgement necessitated removal 8 h post-operatively. Severe haemorrhage ensued, requiring emergency passage of an ETT and cuff inflation for control. In Cases 2 and 3, the ETT was placed electively intraoperatively for post-operative haemostasis. The ETT was easy to use in the standing horse and no discomfort or complications were recorded. It adequately controlled haemorrhage post-operatively by application of controlled pressure to the nasal and sinus vasculature. ETT cuff placement and inflation over surgically created sinonasal windows has the potential to provide simple and reliable haemostasis following standing sinus-flap surgery without the reported complications of conventionally used methods.     

Surgical correction of entrapment of the large colon and caecum through a mesoduodenal rent with standing laparoscopic repair in a mare

A 12-year-old Tennessee Walking Horse mare displaying signs of severe colic for 48 h was found during an exploratory celiotomy to have entrapment of a cranially displaced large colon and the caecum through a rent in the mesoduodenum. The entrapment was relieved, and 24 h later, the mesoduodenal rent was closed laparoscopically, with the mare standing. The owner reported 6 months later that the mare had displayed no signs of colic since being discharged from the hospital 11 days after surgery.