Diagnostic Performance of Multi-Detector Computed Tomography Arthrography and 3-Tesla Magnetic Resonance Imaging to Diagnose Experimentally Created Articular Cartilage Lesions in Equine Cadaver Stifles.

BACKGROUND: The purpose of the study was to determine the diagnostic performance of computed tomographic arthrography (CTA) and 3-Tesla magnetic resonance imaging (MRI) for detecting artificial cartilage lesions in equine femorotibial and femoropatellar joints. METHODS: A total of 79 cartilage defects were created arthroscopically in 15 cadaver stifles from adult horses in eight different locations. In addition, 68 sites served as negative controls. MRI and CTA (80-160 mL iodinated contrast media at 87.5 mg/mL per joint) studies were obtained and evaluated by a radiologist unaware of the lesion distribution. The stifles were macroscopically evaluated, and lesion surface area, depth, and volume were determined. The sensitivity and specificity of MRI and CTA were calculated and compared between modalities. RESULTS: The sensitivity values of CTA (53%) and MRI (66%) were not significantly different (p = 0.09). However, the specificity of CTA (66%) was significantly greater compared to MRI (52%) (p = 0.04). The mean lesion surface area was 11 mm2 (range: 2-54 mm2). Greater lesion surface area resulted in greater odds of lesion detection with CTA but not with MRI. CONCLUSIONS: CTA achieved a similar diagnostic performance compared to high-field MRI in detecting small experimental cartilage lesions. Despite this, CTA showed a higher specificity than MRI, thus making CTA more accurate in diagnosing normal cartilage. Small lesion size was a discriminating factor for lesion detection. In a clinical setting, CTA may be preferred over MRI due to higher availability and easier image acquisition.

Ex vivo comparison of 3 Tesla magnetic resonance imaging and multidetector computed tomography arthrography to identify artificial soft tissue lesions in equine stifles.

OBJECTIVE: To determine the diagnostic performance of computed tomographic arthrography (CTA) and 3 Tesla magnetic resonance imaging (MRI) for detecting artificial meniscal, meniscotibial ligament (MTL) lesions and cruciate ligament (CL) lesions in horses. STUDY DESIGN: Ex vivo controlled laboratory study. ANIMALS: Nineteen stifles from adult horses. METHODS: Stablike defects (n = 84) (16 mm long, 10 mm deep) were created in the menisci (n = 35), CLs (n = 24), and MTLs (n = 25) via arthroscopy prior to MRI and CTA (80 mL contrast at 85 mg/mL per joint). Two radiologists, unaware of the lesions, reached a consensus regarding the presence of lesions, based on 2 reviews of each study. Sensitivity and specificity of MRI and CTA were determined using arthroscopy as a reference and compared with McNemar's tests. RESULTS: The sensitivity and specificity of MRI (41% and 86% respectively) and CTA (32% and 90% respectively) did not differ (P = .65). The sensitivity (MRI: 24%-50%; CTA:19%-40%) and specificity (MRI: 75%-92%; CTA 75%-100%) of imaging modalities did not differ when detecting lesions of the menisci, MTLs, and CLs (P = .1-1.0). The highest sensitivities were achieved when MTLs were evaluated with MRI (50%) and CLs with both modalities (40%). CONCLUSIONS: The diagnostic performance of CTA was comparable with that of MRI, with a low to moderate sensitivity and high specificity. CLINICAL SIGNIFICANCE: Computed tomographic arthrography should be considered as an adjunct to diagnose CL injuries. This is important for equine clinicians, as the CL cannot be visualized adequately using basic imaging techniques preoperatively.

Outcome and complications following transrectal and transabdominal large intestinal trocarization in equids with colic: 228 cases (2004-2015).

OBJECTIVE: To describe outcome and complications after large intestinal trocarization in equids with colic and identify factors associated with nonsurvival and clinically relevant peritonitis (CRP). ANIMALS: 228 (198 horses, 24 ponies, and 6 donkeys and mules) equids with colic that underwent large intestinal trocarization. PROCEDURES: Medical records from 2004 through 2015 were reviewed for equids with colic that underwent large intestinal trocarization. Factors associated with nonsurvival in all (ie, surgically and medically treated) equids and with CRP in medically only treated equids were identified. Medically only treated equids with a high peritoneal fluid cell count (ie, > 10,000 cells/µL) after large intestinal trocarization were classified as having CRP if they met ≥ 2 of the following clinical criteria: anorexia, fever, lethargy, abnormal oral mucous membrane color, abnormal WBC count, or high blood fibrinogen concentration (> 5 g/L). RESULTS: Transabdominal large intestinal trocarization was performed in 190 (83%) equids, transrectal trocarization in 17 (7%), and both procedures in 21 (9%). Of 228 equids, 167 (73%) survived to hospital discharge. None died or were euthanized because of complications from large intestinal trocarization. Nonsurvival was associated with an increasing number of trocarization procedures and diagnosis of a large intestinal strangulating lesion. A diagnosis of nephrosplenic ligament entrapment of the large colon decreased the odds of nonsurvival. Twelve of 60 (20%) equids that received medical treatment only had CRP following large intestinal trocarization. CONCLUSIONS AND CLINICAL RELEVANCE: Large intestinal trocarization could be considered for equids with colic and large intestinal gas distension. More than one trocarization procedure was associated with an increase in nonsurvival, which should be considered for equids for which consent for surgery has been obtained.

The Risk of a Shod and Unshod Horse Kick to Create Orbital Fractures in Equine Cadaveric Skulls.

OBJECTIVE: The aim of this study was to compare the potential of an unshod and shod hoof to cause an orbital fracture in the event of a kick. MATERIALS AND METHODS: Thirty-four equine cadaveric orbitae were exposed to a steel or horn impactor in a dropping test set-up. An impactor velocity of 7 m/s was used for both materials. Testing was repeated on the same orbit at a velocity of 10 m/s with the horn impactor if no damage occurred. A high-speed camera was used to analyse the impact process. Physical parameters (peak force and impact duration) were calculated based on quantitative video-tracking. Computed tomographic (CT) scans were generated and fracture configurations described. RESULTS: At 7 m/s, the fracture probability was lower for horn (23.5%) than for steel impactors (70.6%, p = 0.015). On CT-images, damage of the frontal, temporal, zygomatic and lacrimal bones was detected. Furthermore, the orbital socket (17.2%), the supraorbital foramen (34.5%) and the temporomandibular joint (58.6%) were involved. The frequency of affected orbital bones was not significantly different between fractures generated by steel and horn impactors, but the fracture severity was subjectively greater when fractures were generated by steel impactors. CLINICAL SIGNIFICANCE: The orbital fracture probability was significantly higher when a kick of a shod versus unshod horse was simulated. This indicates that keeping horses unshod would decrease the injury risk of neighbouring horses when considering group housing systems.

Comparison between magnetic resonance imaging, computed tomography, and arthrography to identify artificially induced cartilage defects of the equine carpal joints.

While articular cartilage changes are considered to be one of the initial events in the pathological cascade leading to osteoarthritis, these changes remain difficult to detect using conventional diagnostic imaging modalities such as plain radiography. The aim of this prospective, experimental, methods comparison study was to compare the sensitivity of magnetic resonance imaging (MRI), magnetic resonance arthrography, computed tomography (CT), and CT arthrography in the detection of artificially induced articular cartilage defects in the equine carpal joints. Defects were created in the antebrachiocarpal and middle carpal joint using curettage by a board-certified equine surgeon. Normal articular cartilage thickness varied from a maximum of 1.22 mm at the level of the distal aspect of the radius to a minimum of 0.17 mm in the proximal articular surface of the third carpal bone. Regarding cartilaginous defect measurements the remaining cartilaginous bed range from a maximum of 0.776 mm in the partial thickness defects, and 0 mm (defect reaches the subchondral bone) when total thickness defect were made. Computed tomography and magnetic resonance imaging were performed followed by CT arthrography and magnetic resonance arthrography after antebrachiocarpal and middle carpal intraarticular contrast administration. All images were reviewed by two board-certified veterinary radiologists, both of whom were blinded to the location, presence of, and thickness of the cartilage defects. A total number of 72 lesions in nine limbs were created. Mean sensitivity for localizing cartilage defects varied between imaging modalities with CT arthrography showing the best sensitivity (69.9%), followed by magnetic resonance arthrography (53.5%), MRI (33.3%), and CT (18.1%) respectively. The addition of contrast arthrography in both magnetic resonance and CT improved the rate of cartilage lesion detection although no statistical significance was found. Computed tomographic arthrography displayed the best sensitivity for detecting articular cartilage defects in the equine antebrachiocarpal and middle-carpal joints, compared to magnetic resonance arthrography, MRI, and CT.

Use of a 3-Telsa magnet to perform delayed gadolinium-enhanced magnetic resonance imaging of the distal interphalangeal joint of horses with and without naturally occurring osteoarthritis.

OBJECTIVE To characterize delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) features of healthy hyaline cartilage of the distal interphalangeal joint (DIPJ) of horses, to determine whether dGEMRIC can be used to differentiate various stages of naturally occurring osteoarthritis of the DIPJ, and to correlate relaxation times determined by dGEMRIC with the glycosaminoglycan concentration, water content, and macroscopic and histologic findings of hyaline cartilage of DIPJs with and without osteoarthritis. SAMPLE 1 cadaveric forelimb DIPJ from each of 12 adult warmblood horses. PROCEDURES T1-weighted cartilage relaxation times were obtained for predetermined sites of the DIPJ before (T1preGd) and after (T1postGd) intra-articular gadolinium administration. Corresponding cartilage sites underwent macroscopic, histologic, and immunohistochemical evaluation, and cartilage glycosaminoglycan concentration and water content were determined. Median T1preGd and T1postGd were correlated with macroscopic, histologic, and biochemical data. Mixed generalized linear models were created to evaluate the effects of cartilage site, articular surface, and macroscopic and histologic scores on relaxation times. RESULTS 122 cartilage specimens were analyzed. Median T1postGd was lower than the median T1preGd for normal and diseased cartilage. Both T1preGd and T1postGd were correlated with macroscopic and histologic scores, whereby T1preGd increased and T1postGd decreased as osteoarthritis progressed. There was topographic variation of T1preGd and T1postGd within the DIPJ. Cartilage glycosaminoglycan concentration and water content were significantly correlated with T1preGd and macroscopic and histologic scores but were not correlated with T1postGd. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dGEMRIC relaxation times varied for DIPJs with various degrees of osteoarthritis. These findings may help facilitate early detection of osteoarthritis.

Clinical comparison of dexmedetomidine and medetomidine for isoflurane balanced anaesthesia in horses.

OBJECTIVE: To compare the effects of two balanced anaesthetic protocols (isoflurane-dexmedetomidine versus medetomidine) on sedation, cardiopulmonary function and recovery in horses. STUDY DESIGN: Prospective, blinded, randomized clinical study. ANIMALS: Sixty healthy adult warm blood horses undergoing elective surgery. METHODS: Thirty horses each were sedated with dexmedetomidine 3.5 µg kg-1 (group DEX) or medetomidine 7 µg kg-1 (group MED) intravenously. After assessing and supplementing sedation if necessary, anaesthesia was induced with ketamine/diazepam and maintained with isoflurane in oxygen/air and dexmedetomidine 1.75 µg kg-1 hour-1 or medetomidine 3.5 µg kg-1 hour-1. Ringer's lactate (7-10 mL kg-1 hour-1) and dobutamine were administered to maintain normotension. Controlled mechanical ventilation maintained end-tidal expired carbon dioxide pressures at 40-50 mmHg (5.3-6.7 kPa). Heart rate, invasive arterial blood pressure, inspired and expired gas composition and arterial blood gases were measured. Dexmedetomidine 1 µg kg-1 or medetomidine 2 µg kg-1 was administered for timed and scored recovery phase. Data were analysed using two-way repeated-measures analysis of variance and chi-square test. Significance was considered when p≤0.05. RESULTS: In group DEX, significantly more horses (n=18) did not fulfil the sedation criteria prior to induction and received one or more supplemental doses, whereas in group MED only two horses needed one additional bolus. Median (range) total sedation doses were dexmedetomidine 4 (4-9) µg kg-1 or medetomidine 7 (7-9) µg kg-1. During general anaesthesia, cardiopulmonary parameters did not differ significantly between groups. Recovery scores in group DEX were significantly better than in group MED. CONCLUSIONS AND CLINICAL RELEVANCE: Horses administered dexmedetomidine required more than 50% of the medetomidine dose to reach equivalent sedation. During isoflurane anaesthesia, cardiopulmonary function was comparable between the two groups. Recovery scores following dexmedetomidine were better compared to medetomidine.

Evaluation of the optimal plate position for the fixation of supraglenoid tubercle fractures in warmbloods.

OBJECTIVES: To determine scapular cortex thickness, distal scapular bone density and describe the exact suprascapular nerve course to evaluate the best plate position for the fixation of supraglenoid tubercle fractures in horses. METHODS: Twelve equine cadaveric shoulders were examined with computed tomography. Computed tomography morphometry and density measurements (Hounsfield units [HU]) of the scapula were recorded. Statistical comparisons were made between the cranial and caudal aspects of the scapula. Dissection of each shoulder was performed and the suprascapular nerve course was described morphometrically and morphologically. RESULTS: The suprascapular nerve was found on the periosteum and embedded in connective tissue at the cranial aspect of the scapula. It ramified proximally and distally into the supraspinatus muscle, coursed caudolaterally at a median of 2 cm (1-2 cm) distal to the scapular spine and ramified proximally and distally into the infraspinatus muscle. The scapular cortex measurements (HU) cranially were significantly larger than caudally at most levels of the scapula. The bone density of the distal scapula cranially (651.3 ± 104.2) was significantly lower than caudally (745.7 ± 179.1). CLINICAL SIGNIFICANCE: For surgical access to the supraglenoid tubercle, knowledge of the anatomy is important. It is easiest to avoid the suprascapular nerve at the most cranial aspect of the scapula, where it has not yet ramified. For a stable fixation, knowledge of the characteristics of the equine scapula, such as scapular cortex thickness, is important.

Fixation of supraglenoid tubercle fractures using distal femoral locking plates in three Warmblood horses.

Three horses that were presented with supraglenoid tubercle fractures were treated with open reduction and internal fixation using distal femoral locking plates (DFLP). Placing the DFLP caudal to the scapular spine in order to preserve the suprascapular nerve led to a stable fixation, however, it resulted in infraspinatus muscle atrophy and mild scapulohumeral joint instability (case 1). Placing the DFLP cranial to the scapular spine and under the suprascapular nerve resulted in a stable fixation, however, it resulted in severe atrophy of the supraspinatus and infraspinatus muscles and scapulohumeral joint instability (case 2). Placing the DFLP cranial to the scapular spine and slightly overbending it at the suprascapular nerve passage site resulted in the best outcome (case 3). Only a mild degree of supraspinatus and infraspinatus muscle atrophy was apparent, which resolved quickly and with no effect on scapulohumeral joint stability. In all cases, fixation of supraglenoid tubercle fractures using DFLP in slightly different techniques led to stable fixations with good long-term outcome. One case suffered from a mild incisional infection and plates were removed in two horses. Placement of the DFLP cranial to the scapular spine and slightly overbending it at the suprascapular nerve passage prevented major nerve damage. Further cases investigating the degree of muscle atrophy following the use of the DFLP placed in the above-described technique are justified to improve patient outcome.

Optimal tension, position, and number of prostheses required for maximum rima glottidis area after laryngoplasty.

OBJECTIVES: To evaluate the effect of 3 laryngeal prostheses alone or in combination on rima glottidis area in horses. STUDY DESIGN: Experimental randomized design. SAMPLE POPULATION: Cadaveric equine larynges (n = 22). METHODS: Three prostheses were preplaced in each of 14 larynges. Rima glottidis area was measured after loading each suture in 5 Newton (N) increments from 0 N to 35 N. In 8 larynges, the 3 prostheses were tied alone or in combination at a fixed load of 15 N and rima glottidis area measured. RESULTS: Rima glottidis cross-sectional area increased as the load on each prosthesis increased with maximum area reached at 20 N for each prosthesis. At a fixed load of 15 N, tying 2 and 3 prostheses in combination resulted in a larger rima glottidis cross-sectional area than achieved with each prosthesis alone. CONCLUSIONS: A combination of 2 or 3 prostheses tied at a fixed load of 15 N optimized rima glottidis cross-sectional area irrespective of the anatomic location of the prosthesis.

Effect of age and prostheses location on rima glottidis area in equine cadaveric larynges.

OBJECTIVE: To determine the effect of horse age and laryngeal prosthesis location on rima glottidis area in cadaveric larynges. STUDY DESIGN: Experimental study. ANIMALS: Cadaveric equine larynges (n = 40). METHODS: Specimens were grouped by age: group 1, ≤5 years (n = 18); group 2, >5 to ≤10 years (n = 12); group 3, >10 years (n = 10). A cranial prosthesis was placed through the dorsal cricoid spine at 70% of the distance of the total cricoid length measured from the caudal rim. A dorsal prosthesis was placed through the caudal rim of the cricoid on the dorsal midline. A lateral prosthesis was placed 1.5 cm lateral to the dorsal prosthesis. All prostheses passed through the muscular process. Rima glottidis area was determined after progressively tightening each suture in 5 N increments from 0 N to 35 N using a tensiometer. RESULTS: There was no significant effect of age on the area of the rima glottidis at any load for any of the three prosthesis locations. CONCLUSIONS: Age did not affect the area of the rima glottidis when prostheses were loaded between 5 N and 35 N.

The effect of short- and long-term treatment with manuka honey on second intention healing of contaminated and noncontaminated wounds on the distal aspect of the forelimbs in horses.

OBJECTIVES: To compare the effects of manuka honey and manuka honey gel on second intention healing of noncontaminated distal limb wounds and those contaminated with feces. STUDY DESIGN: Experimental study. ANIMALS: Standardbred horses (n = 10). METHODS: Five full-thickness wounds (2 × 2 cm) were created on both metacarpi. Wounds on 1 forelimb were covered with horse feces for 24 hours. Wounds on the contralateral limb were left uncontaminated. Wounds were assigned to the following 5 different treatments: manuka honey, manuka honey gel or gel applied for 12 days, manuka honey gel applied throughout healing and untreated control. Wound area was measured on day 1 then weekly until day 42 and time to complete healing was recorded. RESULTS: Wounds treated with manuka honey gel throughout healing healed faster than all other wounds (P < .05). Wounds treated with manuka honey and manuka honey gel for 12 days healed faster than gel control and untreated control wounds (P < .05). Wounds treated with manuka honey and manuka honey gel for 12 days and throughout healing were smaller than gel control and untreated control wounds until day 35 (P < .05). Wounds contaminated with feces had greater retraction for 7 days, but healed faster than noncontaminated wounds (P < .05). CONCLUSIONS: Treatment of wounds with manuka honey and manuka honey gel reduced wound retraction and overall healing time compared with gel and untreated control wounds.

A preliminary study on the effect of manuka honey on second-intention healing of contaminated wounds on the distal aspect of the forelimbs of horses.

OBJECTIVE: To determine the effect of manuka honey on second-intention healing of contaminated, full-thickness skin wounds in horses. STUDY DESIGN: Experimental. ANIMALS: Adult Standardbred horses (n = 8). METHODS: One wound was created on the dorsomedial aspect of the third metacarpus in both forelimbs, contaminated with feces, and bandaged for 24 hours. Bandages were removed and wounds rinsed with isotonic saline solution. Wounds on 1 limb had manuka honey applied daily (n = 8) whereas wounds on the contralateral limb received no treatment (n = 8). Bandages were replaced and changed daily for 12 days, after which treatment stopped, bandages were removed, leaving wounds open to heal. Wound area was measured 24 hours after wound creation (day 1), then weekly for 8 weeks. Overall time for healing was recorded. Wound area and rate of healing of treated and control wounds were compared statistically. RESULTS: Treatment with manuka honey decreased wound retraction and treated wounds remained significantly smaller than control wounds until day 42; however, there was no difference in overall healing time between treatment and control wounds. CONCLUSIONS: Treatment with manuka honey reduced wound area by reducing retraction but did not affect overall healing time of full-thickness distal limb wounds using this wound-healing model.

Histomorphologic evaluation of extracorporeal shock wave therapy of the fourth metatarsal bone and the origin of the suspensory ligament in horses without lameness.

OBJECTIVE: To determine via histologic examination and scintigraphy the effect of focused extracorporeal shock wave therapy (ESWT) on normal bone and the bone-ligament interface in horses. ANIMALS: 6 horses without lameness. PROCEDURE: Origins of the suspensory ligament at the metacarpus (35-mm probe depth) and fourth metatarsal bone (5-mm probe depth) were treated twice (days 0 and 16) with 2,000 shocks (energy flux density, 0.15 mJ/mm2). One forelimb and 1 hind limb were randomly treated, and the contralateral limbs served as nontreated controls. Bone scans were performed on days -1 (before ESWT), 3, 16, and 19. Histomorphologic studies of control and treated tissues were performed on day 30. RESULTS: ESWT significantly increased the number of osteoblasts but caused no damage to associated soft tissue structures and did not induce cortical microfractures. A significant correlation between osteoblast numbers and radiopharmaceutical uptake was noticed on lateral views of the hind limb on days 3 and 16 and on caudal views of the forelimb on day 3. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that ESWT has the potential to increase osteoblast numbers in horses. The correlation between increased osteoblast numbers and radio-pharmaceutical uptake 3 days and 16 days after the first ESWT suggested that stimulation of osteogenesis occurred soon after ESWT. No damage to bone or the bone-ligament interface should occur at the settings used in this study, and ESWT can therefore be administered safely in horses.