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OBJECTIVE To develop 3D models of larynges to compare arytenoid abduction measurements between specimens and models, and to investigate the anatomic feasibility of placing an implant across the cricoarytenoid joint (CAJ) with or without arthrotomy. SAMPLES Cadaveric equine larynges (n = 9). PROCEDURES Equine larynges underwent sequential CT scans in a neutral position and with 2 arytenoid treatments: bilateral arytenoid abduction (ABD) and bilateral arytenoid abduction after left cricoarytenoid joint arthrotomy (ARTH). Soft tissue, cartilage, and luminal volume 3-dimensional models were generated. Rima glottidis cross-sectional area (CSA) and left-to-right quotient (LRQ) angles were measured on laryngeal specimens and models. Arytenoid translation, articular contact area, and length of modeled implants placed across the CAJ were measured on models. Data were analyzed using paired t test or ANOVA and Tukey’s post hoc test or non-parametric equivalents (P < .05). RESULTS ARTH CSA was larger for laryngeal specimens than models (P = .0096). There was no difference in all other measures of CSA and LRQ angle between treatment groups or between specimens and models. There was no difference between ABD and ARTH groups for arytenoid cartilage translation, contact area, and implant length. The articular contact area was sufficient for modeled implant placement across the CAJ with a narrow range of implant lengths (17.59 mm to 23.87 mm) across larynges with or without arthrotomy. CLINICAL RELEVANCE These results support further investigation of a CT-guided, minimally invasive surgical procedure. Future studies will evaluate the outcomes of the new procedure for technical precision, biomechanical stability, and post-operative success rates for horses with recurrent laryngeal neuropathy (RLN).

In collaboration with the American College of Veterinary Pathologists

Background: Cranial luxation of the scapulohumeral has been rarely reported in dogs and there is limited information available regarding surgical management of this condition, particularly with respect to long-term functional outcomes.Case Description: This report describes the successful resolution of a chronic traumatic cranial scapulohumeral joint luxation in a dog that was stabilized by cranial transposition of the biceps brachii tendon of origin. At surgery, an osteotomy of the greater tubercle was performed and a trough was made in the exposed bed of the osteotomy. The transverse humeral ligament was incised, and the bicipital tendon was levered into the trough and secured in that location by reattachment of the greater tubercle using multiple Kirschner wires and a figure-of-eight tension band wire. Postoperatively, the dog was maintained in a Spica splint for 2 weeks. Although surgical reduction was performed 4 months after the original injury, the luxation did not recur and the dog did not have appreciable lameness 14 months following the surgery.Conclusion: Although cranial transposition of the bicipital tendon is an invasive procedure, this dog’s scapulohumeral luxation did not recur and the procedure yielded an excellent long-term functional outcome.

In bearded dragons, aneurysms are most commonly observed on the head and neck and in the cranial coelom. A nine-year-old male bearded dragon (Pogona vitticeps) was presented for a ventral tail base swelling. Aspiration yielded frank blood, and Doppler ultrasonography confirmed an aneurysm by demonstrating pulsatile jets into the lumen. Three months later, the animal presented for acute regurgitation and tenesmus. Coelomic ultrasound showed a distended stomach and pyloroduodenal intussusception. An exploratory coeliotomy revealed a tortuous and distended ventral abdominal vein and mesenteric vasculature. The colon and cecum were markedly distended, and intracoelomic blood clots were discovered. Euthanasia was performed. Necropsy revealed a tail base aneurysm, presumably arterial. The walls of the aneurysm exhibited osseous metaplasia and smooth muscle replacement by fibrous connective tissue with no infectious organisms. This case report provides information on a differential diagnosis for tail base swellings in bearded dragons.

Case summary A 1-year-old spayed female domestic shorthair cat presented for evaluation of a non-weight bearing right pelvic limb lameness after falling from a 4 m height. On orthopedic examination there was substantial swelling and pain on manipulation of the right pes. Radiographs were obtained under sedation, and these revealed dorsoproximal luxations of the third, fourth and fifth metatarsophalangeal joints, and lateral rotation of the second digit. Closed manual reduction under sedation was unsuccessful and open reduction under general anesthesia was therefore performed. Combined transarticular pinning and external skeletal fixation were performed to maintain reduction of the third and fourth digits. Marked postoperative swelling of the distal pes and internal rotation of the third and fourth digits were noted within 24 h of surgery. Three weeks postoperatively, the cat had a persistent weight bearing right pelvic limb lameness and minor pin tract inflammation. All implants were removed and the limb was splinted for 1 week. Internal rotation and pin tract inflammation had resolved at the time of splint removal, and the lameness resolved within 6 weeks of surgery. The cat was not lame, but radiographs revealed mild-to-moderate degenerative osteoarthrosis when the cat was evaluated 6 months after surgery. Relevance and novel information There are limited reports describing metatarsophalangeal luxations in cats. Although several surgical techniques have been advocated, specific outcomes in clinical cases have not been reported. This report describes the clinical application and outcome of combined transarticular pinning and external skeletal fixation for the management of multiple metatarsophalangeal luxations in a cat.

The radiographic anatomy of the equine distal tibia is complex and is not widely described in the current literature. Superimposition and radiographic similarities between the different osseous structures of the equine distal tibia can make it difficult for anatomic localization of pathology. The purpose of this prospective, descriptive, anatomic study was to detail the normal anatomy of the equine distal tibia using routine radiographic projections and CT of the equine tarsus. Radiographic identification of the different osseous protuberances of the distal tibia on three cadaveric limbs was achieved using radiopaque markers and evaluation of multiplanar and 3D CT reconstructions to create anatomical maps. It was found that the lateral malleolus is composed of cranial and caudal protuberances that are superimposed over the intermediate cochlear ridge of the distal tibia on the lateromedial, dorsal 45° lateral-plantaromedial, and dorsal 65° medial-plantarolateral oblique views, thereby hindering visualization of the cranial protuberance of the lateral malleolus. The medial malleolus is a simple rounded protuberance with discrete margins. On the dorsal 65° medial-plantarolateral oblique, the medial malleolus is ill-defined due to superimposition with the talus. The intermediate cochlear ridge of the distal tibia extends in a craniolateral to caudomedial direction, with its cranial protuberance largely superimposed with the calcaneus and talus on the dorsoplantar view. In summary, the distal tibial anatomy is complex and a thorough anatomical reference is necessary when reviewing radiographs of the equine tarsus for pathology. A plantaro 15° distal 85° lateral-dorsoproximomedial oblique projection is proposed to isolate all distal tibial protuberances.

Objectives The purpose of this study was to establish a method for feline splenic measurement on abdominal radiographs and evaluate for correlation between the radiographic measurements and ultrasonographic measurements. Methods One hundred cats with normal abdominal radiographs and ultrasound (US) studies of the spleen were evaluated. The hypothesis was that the measurement of the spleen on the radiographs would correlate with the measurement of the spleen on US. The radiographic and ultrasonographic measurements were tabulated and compared using linear regression and t-tests using unequal variances. Results The measurement of the spleen on the ventrodorsal projection was characterized as one of three shapes (A, B or C), and thereby based on the thickest part of the spleen (when corrected for radiographic magnification: A = 9.9 ± 2.2 mm; B = 8.1 ± 1.8 mm; C = 8.0 ± 2.3 mm). There were 48 cats where the head of the spleenwas seen on the right lateral (n = 10), the left lateral (n = 24) or both (n = 14) projections. On one left lateral, both the head and tail of the spleen were seen. There was weak correlation between the radiographic and US measurements(R ⩼0.6). Splenic thickness of shape A on the ventrodorsal projection was significantly greater than categories B and C. Conclusions and relevance Radiographic measurement of the spleen is not a reliable indicator of its ultrasonographic measurement. The ultrasonographic measurements seen in this study (mean of 8.0 ± 1.6 mm) were similar to measurements of the spleen reported in previous studies. It is rare to see the tail of the spleen on lateral feline abdominal radiographs.

Primary hyperparathyroidism is rare in large animal species, and little is known regarding its pathophysiology, endocrine and electrolyte derangements, diagnosis, medical management, and prognosis. This report describes the clinicopathologic diagnosis of a parathyroid (PT) gland chief cell adenoma in a 12-year-old Quarter Horse mare, including PT hormone (PTH) and electrolyte disarrangements associated with the neoplasia, the surgical removal of the adenoma, and medical management of the case. This report also describes for the first time the use PTH immunohistochemistry to confirm the nature of this neoplasia in a horse.

The diagnostic accuracy of contrast-enhanced CT for detection of cervical lymph node metastasis in dogs is unknown. The purpose of this retrospective, observational, diagnostic accuracy study was to assess the efficacy of CT for detection of mandibular and medial retropharyngeal lymph node metastasis in dogs. Histopathology of dogs with cancer of the head, CT and bilateral mandibular and medial retropharyngeal lymphadenectomy was reviewed. A single radiologist measured lymph nodes to derive short axis width and long-short axis ratios. Two blinded radiologists separately assessed lymph node margins, attenuation and contrast enhancement and each provided a final subjective interpretation of each node site as benign or neoplastic. Where radiologists' opinions differed, a consensus was reached. Sensitivity, specificity and accuracy were calculated for mandibular and medial retropharyngeal sites. Agreement between radiologists was assessed. Fisher's exact test and the Kruskal-Wallis H-test were used to assess associations between variables. Forty-one primary tumours were recorded in 40 dogs. Metastasis to mandibular or retropharyngeal lymph nodes occurred in 16 out of 40 dogs (43/160 nodes). Agreement between radiologists was almost perfect for margination, attenuation and enhancement, strong for interpretation of mandibular lymph node metastasis, and weak for interpretation of medial retropharyngeal lymph node metastasis. Sensitivity of CT was 12.5% and 10.5%, specificity was 91.1% and 96.7%, and accuracy was 67.5% and 76.3% for mandibular and medial retropharyngeal lymph nodes respectively. No individual CT findings were predictive of nodal metastasis. Given the low sensitivity of CT, this modality cannot be relied upon alone for assessment of cervical lymph node metastasis in dogs.

Summary A 9-year-old Warmblood gelding underwent magnetic resonance (MR) imaging of the carpal and proximal metacarpal regions for evaluation of prolonged right forelimb lameness. Magnetic resonance findings were indicative of desmopathy of the right lateral carpometacarpal ligament and the interosseous ligament between the third and fourth metacarpal bones. Based on the MR findings and lack of response to conservative therapy, surgery using a drilling technique was performed to facilitate fusion of the right carpometacarpal joint. After surgery and a 6-month rest and rehabilitation programme, the horse returned to soundness. This case report describes a unique combination of lateral carpal/proximal metacarpal soft tissue injuries that resulted in prolonged lameness and were treated with facilitated arthrodesis of the carpometacarpal joint. These soft tissue injuries should be considered as a differential diagnosis in horses with lameness localised to the proximal metacarpal/distal carpal region.

This article addresses the clinical application of magnetic resonance imaging (MRI) and computed tomography (CT) as applied to the standing equine patient. This discussion includes the logistics, advantages, disadvantages, and limitations of imaging a standing horse. In addition, a brief review is given of the physics of these modalities as applied in clinical practice, and the currently available hardware and software required by these techniques for image acquisition and artifact reduction. The appropriate selection of clinical cases for standing MRI and CT is reviewed, focusing on cases that are capable of undergoing standing surgeries following lesion diagnosis.

SummaryScapular luxation is an uncommon cause of forelimb lameness in dogs and cats. Traumatic rupture of the serratus ventralis muscle allows the scapula to displace dorsally during weight-bearing. Specific documentation regarding clinical presentation and surgical techniques is limited, with no medium- to long-term results of surgical intervention in dogs described. Presented here are three cases of scapular luxation in dogs, treated with a modified surgical technique. Clinical outcome was considered good to excellent, with resolution of lameness and abnormal scapular motion in all three dogs. Medium-and long-term outcomes were assessed in two of the dogs, with an excellent outcome in both cases.Supplementary Material to this article is available online at https://doi.org/10.3415/VCOT-16-05-0066

Osteoarthritis of the metacarpophalangeal joint is common cause of lameness in equine athletes, and is hallmarked by articular cartilage damage. An accurate, noninvasive method for measuring cartilage thickness would be beneficial to screen for cartilage injury and allow for prompt initiation of interventional therapy. The objective of this methods comparison study was to compare computed tomographic arthrography (CTA), magnetic resonance imaging (MRI), and magnetic resonance arthrography (MRA) measurements of articular cartilage thickness with gross measurements in the metacarpophalangeal joint of Thoroughbred horses. Fourteen cadaveric, equine thoracic limbs were included. Limbs were excluded from the study if pathology of the metacarpophalangeal articular cartilage was observed with any imaging modality. Articular cartilage thickness was measured in nine regions of the third metacarpal bone and proximal phalanx on sagittal plane MRI sequences. After intra-articular contrast administration, the measurements were repeated on sagittal plane MRA and sagittal CTA reformations. In an effort to increase cartilage conspicuity, the volume of intra-articular contrast was increased from 14.5 ml, to maximal distention for the second set of seven limbs. Mean and standard deviation values were calculated, and linear regression analysis was used to determine correlations between gross and imaging measurements of cartilage thickness. This study failed to identify one imaging test that consistently yielded measurements correlating with gross cartilage thickness. Even with the use of intra-articular contrast, cartilage surfaces were difficult to differentiate in regions where the cartilage surfaces of the proximal phalanx and third metacarpal bone were in close contact with each other.

SummaryA five-week-old American Quarter Horse colt was presented for evaluation of a left hindlimb deformity and lameness. Radiographs of the left hindlimb revealed a varus deformity with recurvatum originating in the middiaphysis of the third metatarsal bone. Surgical correction was undertaken by performing an osteotomy through the centre of rotation of angulation located within the mid-diaphysis of the third metatarsal bone, and a fourring hinged circular external fixator construct was applied. Distraction of the osteotomy site was performed over an 11 day period. Notable complications included failure of a fixation pin, infection of the surgical site, and temporary laxity of the supporting tendons and ligaments of the contralateral metatarsophalangeal joint. The fixator was maintained until there was sufficient bone formation to allow frame removal, 152 days after the initial surgery. Use of a hinged circular construct allowed for partial correction of the deformity with resultant lengthening and resolution of the lameness in this colt.