BARIUM SULFATE GELATIN AS A NOVEL APPROACH TO FACILITATE GASTROINTESTINAL TRACT POSITIVE CONTRAST STUDIES IN A CAPTIVE HARBOR SEAL (PHOCA VITULINA) AND CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS) WITHOUT RESTRAINT.

Gastrointestinal tract contrast medium studies are a valuable diagnostic modality to evaluate gastrointestinal anatomy, motility, and pathology. Four positive contrast medium studies were performed twice on a harbor seal (Phoca vitulina) and once each on two California sea lions (Zalophus californianus) to evaluate for gastrointestinal abnormalities by using barium-impregnated gelatin. Because marine mammals in human care routinely receive plain gelatin as a component of their diet and as secondary reinforcement, feeding a barium gelatin mitigates the need for tube feeding or restraint. Operant conditioning was used to position the pinnipeds for voluntary radiographs. The barium gelatin permitted adequate evaluation of gastric emptying and intestinal transit times and good evaluation of the structure of the intestinal tract. Full evaluation of gastric anatomy was limited due to the gelatin blocks not conforming to the stomach in their solid form and the barium quickly exiting the stomach as barium gelatin blocks disintegrated and because orthogonal views could not always be acquired. Even with these limitations, barium gelatin resulted in diagnostically valuable contrast imaging in a stress-free patient setting with reduced risk of aspiration and eliminated the effects that anesthesia can have on gastric motility as well as other anesthesia-associated risks.

An MRI protocol for anatomical and functional evaluation of the California sea lion brain.

BACKGROUND: Domoic acid (DOM) is a neurotoxin produced by some harmful algae blooms in coastal waters. California sea lions (Zalophus californianus) exposed to DOM often strand on beaches where they exhibit a variety of symptoms, including seizures. These animals typically show hippocampal atrophy on MRI scans. NEW METHOD: We describe an MRI protocol for comprehensive evaluation of DOM toxicosis in the sea lion brain. We intend to study brain development in pups exposed in utero. The protocol depicts the hippocampal formation as the primary region of interest. We include scans for quantitative morphometry, functional and structural connectivity, and a cerebral blood flow map. RESULTS: High-resolution 3D anatomical scans facilitate post hoc slicing in arbitrary planes and accurate morphometry. We demonstrate the first cerebral blood flow map using MRI, and the first structural tractography from a live sea lion brain. COMPARISON WITH EXISTING METHODS: Scans were compared to prior anatomical and functional studies in live sea lions, and structural connectivity in post mortem specimens. Hippocampal volumes were broadly in line with prior studies, with differences likely attributable to the 3D approach used here. Functional connectivity of the dorsal left hippocampus matched that found in a prior study conducted at a lower magnetic field, while structural connectivity in the live brain agreed with findings observed in post mortem studies. CONCLUSIONS: Our protocol provides a comprehensive, longitudinal view of the functional and anatomical changes expected to result from DOM toxicosis. It can also screen for other common neurological pathologies and is suitable for any pinniped that can fit inside an MRI scanner.

Algal toxin impairs sea lion memory and hippocampal connectivity, with implications for strandings.

Domoic acid (DA) is a naturally occurring neurotoxin known to harm marine animals. DA-producing algal blooms are increasing in size and frequency. Although chronic exposure is known to produce brain lesions, the influence of DA toxicosis on behavior in wild animals is unknown. We showed, in a large sample of wild sea lions, that spatial memory deficits are predicted by the extent of right dorsal hippocampal lesions related to natural exposure to DA and that exposure also disrupts hippocampal-thalamic brain networks. Because sea lions are dynamic foragers that rely on flexible navigation, impaired spatial memory may affect survival in the wild.

LAPAROSCOPIC GASTROPEXY FOR CORRECTION OF A HIATAL HERNIA IN A NORTHERN ELEPHANT SEAL (MIROUNGA ANGUSTIROSTRIS).

A female northern elephant seal (Mirounga angustirostris) weaned pup presented with malnutrition. During rehabilitation, the seal developed regurgitation and reduced lung sounds on auscultation. Radiographs and endoscopy performed under sedation suggested a diaphragmatic hernia. A Type I (or sliding) hiatal hernia was confirmed with a positive contrast upper gastrointestinal study, revealing varying degrees of herniation of the gastric fundus through the diaphragm into the caudal thorax as well as esophageal reflux. The animal was treated preoperatively with an H2 antagonist and antinausea medication. A laparoscopic gastropexy was performed under general anesthesia. The animal recovered well postoperatively and resolution of clinical signs was achieved. The animal was released back into the wild 21 kg above admit weight. To our knowledge, we report here the first surgical correction of a hiatal hernia in a marine mammal.

Retroperitoneal hemangiosarcoma in a common carp Cyprinus carpio: a case report.

A 7.5 kg common carp Cyprinus carpio presented with prominent localized swelling in the caudal right coelomic area, identified by ultrasound as a fluid filled mass. Fine needle aspirate (FNA) and culture results suggested a sterile seroma. Centesis removed 290 ml of serosanguinous fluid that returned within days. Recheck ultrasonography revealed a solid component within the cavity. Radiography demonstrated irregular lysis and misalignment of vertebrae adjacent to the mass, most suggestive of bacterial osteitis or neoplasia. Treatment with antibiotics followed for 2 mo but failed to resolve the lesion. Repeated radiography and ultrasonography showed progressive enlargement of the mass, with vertebral lysis and invasion characteristic of neoplasia. Ultrasound-guided FNA of the solid component of the mass was non-diagnostic. Euthanasia was elected due to the poor clinical response and primary differential of neoplasia. Post-mortem MRI and CT confirmed a retroperitoneal soft tissue mass, partially surrounded by a fluid-filled cavity, causing vertebral lysis and infiltration of the spinal canal. Expansion of the mass caused severe muscle loss and an associated elevation in creatine kinase (>120000 U l-1). Necropsy results corroborated the MRI and CT findings, revealing a retroperitoneal, multilobular, red and tan mass causing dorsal displacement of the vertebral column, with vertebral lysis, pathologic fracture and invasion of the spinal canal. Histopathologic examination revealed a locally aggressive neoplasm exhibiting multiple patterns of growth, including endothelial lined vascular channels and solid areas formed by more pleomorphic polygonal and spindle cells, consistent with hemangiosarcoma.

Antemortem diagnosis of a ventricular septal defect in a California sea lion Zalophus californianus.

A yearling California sea lion Zalophus californianus stranded in poor body condition, and on physical examination a heart murmur was audible bilaterally. The sea lion was diagnosed with a left-to-right shunting membranous ventricular septal defect (VSD) using B-mode, color-flow Doppler and continuous-wave Doppler echocardiography. A left-to-right intracardiac shunting lesion was confirmed during cardiac angiographic computed tomography. The VSD defect was verified during the necropsy examination. On histologic examination concurrent mild multifocal myocarditis with focal mild ventricular free-wall myocardial necrosis were identified. A specific cause for the myocarditis and myocardial necrosis was not found, and association with the VSD and resultant myocardial dysfunction was presumed. This is the first report of the antemortem diagnosis of a VSD in a marine mammal and the first report of a VSD in a California sea lion.

An in-house phantom as an alternative to commercially available Doppler flow phantoms.

Learning the principles and application of Doppler ultrasound is difficult and requires repeated practice. Flow phantoms provide a method of teaching Doppler techniques before their application in clinical patients; however, commercially available flow phantoms are expensive. Herein we describe an easily constructed, economic Doppler flow phantom, utilizing readily available products, for use as a training aid.

Standardized protocols for plasma clearance of iohexol are not appropriate for determination of glomerular filtration rates in anesthetized California sea lions (Zalophus californianus).

Abstract: Plasma clearance of iohexol was evaluated in eight anesthetized California sea lions (Zalophus californianus), without evidence of renal dysfunction, to determine if the one-compartment model and the sample protocol used in dogs and cats could be applied to this species. Nonlinearity between samples in 75% (6/8) of sea lions voided those results. An additional two anesthetized sea lions were sampled at 5, 30, 45, 60, 120, 180, 240, and 360 min post iohexol injection and semi-logarithmic curves calculated. Plasma iohexol clearance values calculated by one-, two-, and noncompartment models were in poor agreement, suggesting that the standardized protocol described for dogs and cats cannot simply be applied to California sea lions, probably due to the effects of the dive reflex induced during anesthesia.

Evaluation of different computed tomography techniques and myelography for the diagnosis of acute canine myelopathy.

Forty-six dogs with either cervical (C1-C5 or C6-T2) or thoracolumbar (T3-L3) acute myelopathy underwent prospective conventional computed tomography (CT), angiographic CT, myelography, and CT myelography. Findings were confirmed at either surgery or necropsy. Seventy-eight percent of lesions were extradural, 11% were extradural with an intramedullary abnormality, 7% were intramedullary, 2% were intradural-extramedullary, and 2% had nerve root compression without spinal cord compression. Intervertebral disc herniation was the most frequent abnormality regardless of signalment or neurolocalization. Twenty-one of 23 Hansen type I disc extrusions but none of the Hansen type II disc protrusions were mineralized. Two chondrodystrophic dogs had acute myelopathy attributable to extradural hemorrhage and subarachnoid cyst. CT myelography had the highest interobserver agreement, was the most sensitive technique for identification of compression, demonstrating lesions in 8% of dogs interpreted as normal from myelography and enabling localization and lateralization in 8% of lesions incompletely localized on myelography due to concurrent spinal cord swelling. None of the imaging techniques evaluated permitted definitive diagnosis of spinal cord infarction or meningomyelitis but myelography and CT myelography did rule out a surgical lesion in those cases. While conventional CT was adequate for the diagnosis and localization of mineralized Hansen type I disc extrusions in chondrodystrophic breeds, if no lesion was identified, plegia was present due to concurrent extradural compression and spinal cord swelling, or the dog was nonchondrodystrophic, CT myelography was often necessary for correct diagnosis.

Effect of anesthesia, positioning, time, and feeding on the proventriculus: keel ratio of clinically healthy parrots.

Healthy, adult Hispaniolan Amazon parrots (Amazona ventralis) were imaged on three occasions to determine the effects of anesthesia, patient rotation, feeding, and short/long-term temporal factors on the proventriculus:keel ratio. Increasing rotation up to 15 degrees from right lateral resulted in increased inability to measure the proventriculus in up to 44% of birds, meaning that the proventriculus:keel ratio could not be calculated from those radiographs. There was a significant difference between the proventriculus:keel ratio for individual parrots when quantified 3 weeks apart. Despite this difference, all ratios remained within normal limits. No significant effect was identified due to anesthesia, feeding, fasting, or repeated imaging through an 8-h period. Interobserver agreement for measurability and correlation for the proventriculus:keel ratio values was high. It is recommended that the proventriculus:keel ratio be calculated from anesthetized parrots to attain images in true lateral recumbency. Ratio fluctuations within the normal range between radiographs obtained on different dates may be observed in normal parrots.

Prognostic accuracy of the proventriculus: keel ratio for short-term survival in psittacines with proventricular disease.

The proventriculus:keel ratio was evaluated as a prognostic indicator for short-term survival in parrots with proventricular disease. Measurements were made from right lateral radiographs of 41 parrots with proventricular disease. Results were compared with the previously described abnormal proventriculus:keel ratio range and to short-term clinical outcome at 1-month postdiagnosis. The ratio in all parrots was > 0.52, and 39% of parrots succumbed to their disease within 1 month of diagnosis. There was no significant association between the proventriculus:keel ratio and survival duration (P = 0.9). The proventriculus:keel ratio is a sensitive indicator of proventricular disease in parrots but is insensitive as a prognostic indicator.

Concurrent occipital bone malformation and atlantoaxial subluxation in a neonatal harbor seal (Phoca vitulina).

A stranded male harbor seal (Phoca vitulina) neonate with progressive clinical signs of ataxia, tremors, and deteriorating consciousness was evaluated using magnetic resonance imaging for suspected cerebellar brain disease prior to euthanasia because of grave prognosis. Magnetic resonance imaging identified occipital bone dysplasia with cerebellar herniation and concurrent atlantoaxial subluxation with spinal cord compression. These imaging findings elucidated the cause of histopathology changes including gliosis of the cerebellum and axonal degeneration and dilation of myelin sheaths of the dorsal funiculus of the spinal cord. Occipital bone dysplasia and/ or atlantoaxial subluxation should be considered as differentials for abnormal neurologic signs in harbor seal neonates. Magnetic resonance imaging is a valuable modality for antemortem diagnosis.

Computed tomographic imaging protocol for the canine cervical and lumbar spine.

Computed tomography (CT) has been applied previously for assessment of canine spinal disease using a multitude of different technical imaging parameters. The purpose of this study was to establish an optimized imaging protocol for the cervical and lumbar canine spine using a single-detector-row helical CT unit. Thin slice thickness (1-2mm), low pitch (axial scan mode, helical pitch <2), and medium-frequency image reconstruction algorithm significantly improved the visibility of the intervertebral disk and spinal cord. Tube current, helical reconstruction interval, and the use of an additional edge enhancement filter had no significant effect on the visibility of the intervertebral disk and spinal cord. There was also no interaction between the use of an additional edge enhancement filter and image reconstruction algorithm. Use of an additional edge enhancement filter introduced a double ring artifact in the periphery of the spinal canal lumen that did not correspond to the spinal cord or pachymeningeal margin.

Computed tomographic imaging of the normal immature California sea lion head (Zalophus californianus).

Different computed tomography (CT) protocols were tested to optimize imaging of the head of the California sea lion. Transverse mode images were superior to helical mode images. Bone structures were best imaged using 1 mm slice width combined with a high-frequency image reconstruction algorithm and best viewed using a wide window setting. Soft tissue structures were generally difficult to differentiate with the exception of the orbital region, which was best imaged using 2mm slice width combined with a medium-frequency image reconstruction algorithm and best viewed using a narrow window setting. Anatomic features specific to the California sea lion were identified on CT images and were consistent with previously published data. These included absence of the lacrimal bone, nasolacrimal ducts, and paranasal sinuses. Upon qualitative assessment of the orbit and nasal cavity, there was a triangular-shaped interorbital nasal cavity on transverse images, and extensive, highly convoluted ethmoid turbinates. The permanent dental formula was identical to previous reports. In conclusion, we provide a detailed description of the anatomy of the immature California sea lion head and a definition of two imaging protocols.

Radiographic determination of proventricular diameter in psittacine birds.

OBJECTIVE: To establish an objective method of determining proventricular diameter in psittacine birds by assessment of lateral whole-body radiographic views. DESIGN: Retrospective case-control study. ANIMALS: 100 parrots with no signs of gastric disease and 19 parrots with signs of gastric disease. PROCEDURES: Measurements were obtained for the following variables: proventricular diameter at the level of the junction between the last thoracic vertebra and synsacrum, maximum distance between the dorsal serosa of the proximal aspect of the proventriculus and dorsal border of the sternum, maximum coelomic cavity height at the level of the proximal aspect of the proventriculus, and maximum dorsoventral height of the keel of the sternum. The ratio of proventricular diameter to each of those measurements was calculated and compared among species within the group without signs of gastric disease and between the gastric and nongastric disease groups. RESULTS: No significant differences were seen among species of parrots without signs of gastric disease for any ratio, but there were significant differences between parrots with gastric signs and those without gastric signs for all ratios. Only the proventricular diameterto-maximum dorsoventral height of the keel of the sternum ratio had no numeric overlap between groups. Sensitivity and specificity of the ratio for detection of proventricular enlargement were both 100%. Six causes associated with proventricular enlargement were identified. CONCLUSIONS AND CLINICAL RELEVANCE: Evaluation of the proventricular diameter-to-keel height ratio is a new method for evaluating proventricular size in psittacines. Ratio values < 0.48 indicate normal proventricular diameter and the absence of proventricular disease.