In vitro evaluation of a closed-bowel technique for one-layer hand-sewn inverting end-to-end jejunojejunosotomy in the horse

OBJECTIVE: To report a technique for closed-bowel 1-layer inverting end-to-end jejunojejunal anastomosis in horses. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Fresh cadaveric jejunal segments from 12 horses. METHODS: For each bowel segment a 1-layer closed and a 2-layer inverting end-to-end jejunojejunosotomy was created. Anastomosis construction time and anastomotic bursting pressure were measured and compared. RESULTS: Closed-bowel anastomosis was significantly faster to create than a 2-layer technique. Luminal narrowing (<30%) was similar with both techniques and comparable with other inverting techniques. Bursting pressure was significantly higher for the 2-layer technique, although all anastomoses resisted pressures higher than those reported for other jejunojejunal anastomosis techniques. CONCLUSIONS: A 1-layer hand-sewn, closed, inverting jejunojejunosotomy using a modified Doyen clamp was easy and faster to perform, and resulted in functional characteristics similar to, a 2-layer hand-sewn inverting technique. CLINICAL RELEVANCE: A closed, 1-layer inverting technique could be considered for equine jejunal anastomosis but requires in vivo evaluation before recommendation for clinical use.     

Mediastinal lymphoma with complete atrioventricular block in a horse

A 15-year-old, neutered-male pony presented with a history of weight loss during 4 months. Clinical evaluation revealed severe bradycardia and complete atrioventricular block. At necropsy, a lobulated mass in the anterior mediastinum and moderate enlargement of the superficial cervical lymph nodes were observed. The vagus nerve and the brachiocephalic trunk were embedded in this anterior mediastinal tumor. Histologically, the mass was composed of sheets of neoplastic lymphoid cells expressing CD3, with a low mitotic rate. To the best of our knowledge, this is the first reported case of mediastinal lymphoma associated with complete atrioventricular block in horses.     

A technique for assessing hoof function in the horse

This paper describes the application of foil strain gauges to the hoof wall, and the use of measuring equipment to monitor weightbearing and changes in hoof shape in shod and unshod horses. It concludes that the systems can detect hoof movement and that results are reproducible. It is also concluded that the use of a conventional nailed on iron shoe restricts flexion and spreading of the hoof wall at the ground surface, but has little effect on the degree of expansion of the heels of the foot.     

A technique for pelvic radiography in the standing horse

REASONS FOR PERFORMING STUDY: An alternative technique of radiographing the pelvis in the standing horse is required, to avoid the risks associated with general anaesthesia. HYPOTHESIS: That lateral oblique radiography in the standing horse would be a useful technique in the investigation of pelvic injury. OBJECTIVES: To describe the technique of lateral oblique pelvic radiography in the standing horse and demonstrate the feasibility and usefulness of this technique. METHODS: A technique for lateral oblique radiography in the standing horse was devised and retrospective review made of radiographic findings in 18 clinical cases. RESULTS: The caudal iliac shaft, greater trochanter of the femur, femoral head, acetabulum and coxofemoral articulation on the side under investigation were visualised consistently using this technique. Of the 18 cases, 3 iliac shaft fractures, 1 acetabular fracture, 2 coxofemoral luxations and 4 horses with new bone formation around the coxofemoral joint and/or proximal femur were identified. CONCLUSIONS: Lateral oblique radiography in the standing, conscious horse can be used to investigate conditions affecting the caudal iliac shaft, coxofemoral articulation and proximal femur in the horse. POTENTIAL RELEVANCE: The technique is straightforward, noninvasive and useful in the investigation of horses with suspected pelvic injury. However, not all pelvic injuries would be identified, and normal radiographic findings do not rule out injury or fractures elsewhere in the pelvis.     

Atlanto-axial approach for cervical myelography in a Thoroughbred horse with complete fusion of the atlanto-occipital bones

A 2-year-old Thoroughbred gelding with clinical signs localized to the first 6 spinal cord segments (C1 to C6) had complete fusion of the atlanto-occipital bones which precluded performing a routine myelogram. An ultrasound-assisted myelogram at the intervertebral space between the atlas and axis was successfully done and identified a marked extradural compressive myelopathy at the level of the atlas and axis, and axis and third cervical vertebrae.     

Technical note: a 2-stage cecal cannulation technique in standing horses

Cecal cannulation is necessary for sampling of intestinal contents for a variety of nutritional or digestive physiology studies. This report describes a 2-stage technique for permanent cecal cannulation in standing horses. For the first procedure, a right flank laparotomy is performed and a small pouch of the cecal base exteriorized and sutured to the body wall. The second procedure is performed approximately 1 wk later. During the second procedure, the exposed cecal pouch is removed and the cannula inserted. Ten horses were cannulated using this technique. After the first procedure, 1 horse developed a cecal impaction unresponsive to medical therapy and ruptured its cecum, whereas 2 other horses developed mild transient colic that responded to medical management. Insertion of the cecal cannula after creation of the stoma in the second procedure resulted in transient colic in 4 of 9 horses, but they responded to analgesic therapy in less than 24 h in all instances. The time to complete healing of the cannula site was approximately 30 d. The technique described in this report decreases the risk of peritonitis due to intestinal leakage and is technically easier to perform than previously described techniques.     

Use of computed tomography angiography for the evaluation of a cutaneous haemangioma in a Standardbred horse

Cutaneous haeangiomas are benign vascular neoplasms that arise from endothelial cells of blood vessels. Haemangiomas account for 0.6%–4% of all equine cutaneous neoplasms and the fetlock is the most commonly affected site. We describe the use of computed tomography angiography (CTA) for the evaluation of a cutaneous haemangioma located on the plantarolateral aspect of the left hindlimb fetlock of a 9-month-old Standardbred colt. Computed tomography angiography of the affected fetlock was performed under general anaesthesia. The medial plantar artery was catheterised and a total volume of 50 ml of iodinated non-ionic contrast medium (Iopamidol, 300 mg I/ml, Bracco Imaging Canada) was injected at a rate of 2 ml/s. Following contrast medium administration, the dorsal metatarsal artery and branches including the lateral and medial digital arteries were well demarcated. Two smaller lateral and medial arteries were also identified, forming the vascular network of the metatarsophalangeal joint. At the level of the haemangioma, two tortuous arteries arising from the lateral digital artery were identified, in addition to multiple small branches from nearby cutaneous arteries. These vessels supplied the homogeneously strongly contrast-enhancing cutaneous mass. The initial goal of the CTA study was to map the vascular anatomy for arterial embolisation in conjunction with pharmacological therapy. Considering the involvement of multiple small arterial branches, complete surgical excision along with ligation of the two main supplying arteries was alternatively elected, resulting in a successful long-term outcome.     

A new technique for accessing the cerebral ventricles of the horse

A technique is described for catheterisation of the ventricular recess within the olfactory bulb of the horse. Twelve adult horses were used. The olfactory recess is in the frontal region, 42±3 mm below the skin, on the line joining the supraorbital foramina, and approximately 18±2 mm from the midline. The approach is relatively easy under normal experimental conditions.     

Treatment of granular cell tumor via complete right lung resection in a horse

A 7-year-old warmblood mare was referred because of a respiratory tract disorder; pulmonary granular cell tumor was diagnosed. Pulmonary granular cell tumor is a locally invasive but rare type of tumor with low metastatic potential. The entire right lung was resected to ensure removal of all neoplastic tissue. The horse recovered well and has minimal difficulties functioning with one lung. Most of these tumors are diagnosed during postmortem examination. To our knowledge, this is the first report of pulmonary granular cell tumor treated by complete lung resection in a horse.     

Validation of a cranial injection technique of the medial femorotibial joint in the horse

A cranial technique for entry of the medial femorotibial (MFT) joint in the horse was validated. It was hypothesised that the frequency of correct placement into the MFT joint using the described cranial technique would be similar to using a standard medial approach. Twenty‐four limbs from 15 horses were injected with a latex mixture. Limbs with stifle joint effusion and/or known stifle pathology were grouped separately to those without. When effusion/pathology was not present the medial technique (93%) was almost twice as successful as the cranial technique (53%), including when extremes of size were removed from the population. With the presence of femoropatellar or medial femorotibial effusion, the cranial technique (20%) was 5 times less successful than using the medial technique (100%). When extremes of size were removed from the population of horses with effusion, the success of the cranial technique was marginally improved (33%). When an ‘average size’ of horse is used with or without joint effusion, the cranial technique is successful in entering the MFT joint in approximately 50% of cases, and may hence be of use in a fractious animal without sedation, a stallion, or in the presence of a wound/skin infection at the site of the medial needle entrance.     

Dental dolorimetry for the evaluation of an analgesic agent in the horse

A monopolar electrode was implanted surgically in the canine tooth dentine layer to evaluate pain threshold responses of horses. A constant-current stimulator was used to deliver a known electrical current to the tooth pulp nerve. A single stimulus of 2-ms duration, repeated at greater than or equal to 20-s intervals, was used to elicit a head lift response. The lowest current level that produced 3 positive head lift responses was recorded as the pain threshold of the horse. The testing technique, dental dolorimetry, was easily performed. Tooth pulp pain thresholds (TPPT) were established on 8 nonmedicated adult male horses. Electrodes were nonreactive and remained functional for up to 98 days. Base-line TPPT values were consistent with repeated measurements on the same day and measurements on subsequent test days. The quantity of electrical current necessary to elicit the TPPT was increased after administration of xylazine HCl as a test analgesic.     

Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse

Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These periods of profound bradycardia were corrected by temporary right ventricular pacing until spontaneous conduction resumed. It is concluded that temporary right ventricular pacing should be available during electrical cardioversion of atrial fibrillation in horses.     

A simplified surgical technique for correction of orbital adipose prolapse in the horse

A Quarter Horse gelding underwent standing surgical correction of an orbital adipose prolapse through a subconjunctival approach removing the prolapsed fat without use of electrocautery or closure of the conjunctiva. This technique provided an acceptable long‐term cosmetic outcome. There was no recurrence of orbital adipose prolapse up to 15 months post operatively. The surgical procedure performed in this case is a simple technique, which could be performed in the field under sedation and local anaesthesia.     

Computed tomography and scintigraphy for evaluation of dental disease in the horse

Computed tomography (CT) uses x‐ray beams and reconstructive computer technology to create tomographic slices (sections) of the area being imaged. Computed tomography has higher contrast resolution than conventional radiography allowing for more accurate differentiation of soft tissues and fluids. This form of 3D imaging removes problems caused by superimposition of multiple anatomical structures, which is a major impediment when viewing radiographs of the equine head. Once the images are acquired, multi‐planar and 3D reconstructions can be performed to view different teeth or associated structures in an optimal way. Anatomical and pathological changes in the dental tissues, periodontal tissues, alveolar bone and adjacent sinuses can then be assessed. Scintigraphy with 99^m technetium methyl‐diphosphate (methylene‐diphosphonate) can detect changes in bone that precede radiographic changes, and this makes it a very useful imaging modality for diagnosis of early periapical infection of the equine cheek teeth. Additionally, it is invaluable for imaging suspected infections of supernumerary or dysplastic teeth where the results of radiography or even CT may be equivocal. Periapical infections of the cheek teeth typically result in focal and intense increased radionuclide uptake located over the apical region of the affected tooth.     

A tracheal tube-in-tube technique for functional separation of the lungs in the horse.

The tube-in-tube technique for the functional separation of the lungs in intact anaesthetised adult horses is based on fibre-optic-guided left-sided endobronchial intubation avoiding tracheostomy. It facilitates a valid separation of the two lungs despite variability in bronchial and carinal anatomy. No clinical complications that could be related to its use have been seen.