Biomechanical analysis of 3 fixation techniques in rabbit radius and humerus bones.

The objective of this study was to compare the strength and stiffness of various fixation methods applied to the long bones of the rabbit forelimb. Twenty rabbit radius/ulna and 20 rabbit humeri were randomly assigned to 1 of 4 groups. Control bones remained intact, whereas all others were osteotomized to create fracture models that were fixated with locking plate and locking screws (LP), veterinary cuttable plate (VCP) with cortical screws, or external skeletal fixator constructs (ESF), and tested in 4-point bending until failure. Load/deformation curves were generated for each sample and used to calculate stiffness (slope of the curve) and strength (load to failure). Intact controls had greater strength and stiffness than any fixation techniques in the rabbit radius/ulna and humeri samples. Locking plate and VCP constructs had greater stiffness than ESF when applied to the radius, whereas locking plate constructs were stronger than VCP or ESF when applied to the humerus. Overall, the LP construct had characteristics most closely resembling those of the intact control regarding strength in the humerus. Therefore, fracture fixation with a LP would provide the greatest strength in humeral fracture repairs in the rabbit.

Analyse biomécanique de trois techniques de fixation du radius et de l'humérus de lapin. L'objectif de cette étude était de comparer la résistance et la rigidité de différentes méthodes de fixation appliquées aux os longs du membre antérieur du lapin. Vingt radius/cubitus de lapin et 20 humérus de lapin ont été assignés au hasard à un des quatre groupes. Les os témoins sont restés intacts, tandis que tous les autres ont été ostéotomisés pour créer des modèles de fracture qui ont été fixés avec une plaque de verrouillage et des vis de verrouillage (LP), une plaque vétérinaire découpable (VCP) avec des vis corticales ou des constructions de fixateur squelettique externe (ESF), et testés dans une flexion en quatre points jusqu'à la rupture. Des courbes de charge/déformation ont été générées pour chaque échantillon et utilisées pour calculer la rigidité (pente de la courbe) et la résistance (charge à la rupture). Les témoins intacts avaient une résistance et une rigidité supérieures à toutes les techniques de fixation dans les échantillons de radius/cubitus et d'humérus de lapin. Les constructions à plaque de verrouillage et VCP avaient une plus grande rigidité que l'ESF lorsqu'elles étaient appliquées au radius, tandis que les constructions à plaque de verrouillage étaient plus solides que VCP ou ESF lorsqu'elles étaient appliquées à l'humérus. Dans l'ensemble, la construction LP avait des caractéristiques ressemblant le plus à celles du témoin intact en ce qui concerne la force de l'humérus. Par conséquent, la fixation des fractures avec un LP fournirait la plus grande résistance dans les réparations des fractures humérales chez le lapin.(Traduit par Dr Serge Messier).

PROGRESSIVE SYRINGOHYDROMYELIA AND DEGENERATIVE AXONOPATHY IN A BOBCAT (LYNX RUFUS) FOLLOWING SURGICAL CORRECTION OF A CHIARI-LIKE MALFORMATION.

A 3-yr-old male captive bobcat (Lynx rufus) presented with chronic ataxia and right-sided head tilt. Magnetic resonance imaging (MRI) revealed cerebellar crowding and compression consistent with Chiari-like malformation. The clinical signs did not improve after surgical occipital craniectomy, and 2 mo postoperatively a second MRI showed hydromyelia and continued cerebellar compression. The bobcat was euthanized, and necropsy showed chronic focal cerebellar herniation and chronic multifocal atlanto-occipital joint osteophyte proliferation. Histology confirmed the presence of a thick fibrous membrane along the caudal aspect of the cerebellar vermis, suggestive of postoperative adhesions, and axonal degeneration of the cervical spinal cord, even in sections without a central canal lesion. These lesions appear to have been complications associated with surgical correction of the Chiari-like malformation.

Pericardial Mesothelioma in a Yellow-naped Amazon Parrot (Amazona auropalliata).

A 37-year-old female yellow-naped Amazon parrot (Amazona auropalliata) was presented with a history of lethargy, inappetence, and decreased vocalizations. On examination, the coelom was moderately distended and palpated fluctuant, and the heart was muffled on auscultation. Coelomic ultrasound, coelomocentesis, and radiographs were performed and revealed an enlarged cardiac silhouette and marked coelomic effusion. Pericardial effusion was confirmed by echocardiography. A well-circumscribed, hyperechoic soft tissue density was observed at the level of the right atrium on initial echocardiography; however, a cardiac mass was not identified by computed tomography scan or repeat echocardiograms. Ultrasound-guided pericardiocentesis was performed under anesthesia, and cytology results were consistent with hemorrhage; no neoplastic cells were identified. A repeat echocardiogram 4 days after pericardiocentesis revealed recurrence of the pericardial effusion. Due to the grave prognosis, the owners declined endoscopic pericardiectomy, and the patient died the following day. On postmortem examination, the pericardial surface of the heart was covered in a white to yellow, multinodular mass layer. Histologic analysis revealed a multinodular mass extending from the atria, running along the epicardium distally, and often extending into the myocardium. Neoplastic cells present in the heart mass and pericardium did not stain with a Churukian-Schenk stain, and thyroglobulin immunohistochemistry was negative. Cytokeratin and vimentin stains showed positive expression in the neoplastic cells within the mass. These results are consistent with a diagnosis of mesothelioma. This is the first report of mesothelioma in a psittacine bird.

Branchial Cyst With Carcinoma in an Umbrella Cockatoo (Cacatua alba).

A 16-year-old female umbrella cockatoo (Cacatua alba) was presented for a fluctuant, right-sided cervical mass that extended from the caudolateral edge of the right mandible to the coelomic inlet. Results of initial diagnostic tests were consistent with a cystic mass containing hemorrhage. Surgical exploration and removal of the mass was done, but because the hyoid apparatus was incorporated in the base of the cyst, complete surgical excision was not possible. Histopathologic results were consistent with a branchial cyst with carcinoma. Five months after surgery, the cockatoo exhibited intermittent periorbital swelling and epistaxis, and cytologic results of a fluid aspirate from the right infraorbital sinus were consistent with carcinoma. Results of magnetic resonance imaging revealed extensive abnormal T2 and short-tau inversion-recovery hyperintense tissue associated with the right side of the head and neck, infiltrating between muscle planes and extending into the right retro-orbital tissue and nasal cavity. At 7 months after surgery, the bird was severely dyspneic and was euthanatized. To our knowledge, this is the first report describing the diagnosis, management, and histologic characteristics associated with a branchial cyst with carcinoma in an animal.

Maxillary Ameloblastoma in an Asiatic Black Bear (Ursus thibetanus).

An approximately 30-year-old intact female Asiatic black bear (Ursus thibetanus) was presented for annual examination and a history of ptyalism. A large 9.5 cm × 5 cm × 5 cm, firm, round mass was identified attached to the hard palate on physical examination. A computed tomography scan was performed, and the heterogeneous, mineral-attenuating mass was seen arising from the right aspect of the palatine bone and extending rostrally to the level of the last maxillary molars, caudally into the oropharynx, and dorsally into the nasal choana. Surgical debulking was performed to remove the portion of the mass within the oral cavity. Histopathologic analysis was consistent with a keratinizing ameloblastoma. Nine months postoperatively, the patient was asymptomatic for the tumor. The patient was euthanized 23-months postoperatively, and severe diffuse pustular dermatitis, growth of the ameloblastoma on the hard palate, and various degenerative and aging changes were noted on necropsy at that time. This is the first report of an ameloblastoma in a member of the Ursidae family.

Comparative infectiousness of three passerine bird species after experimental inoculation with Mycoplasma gallisepticum.

Mycoplasma gallisepticum has been isolated from various species of free-living birds, and we therefore tested the hypothesis that bird species other than the main host, the house finch (Carpodacus mexicanus), could play a role in the epidemiology of the infection. We compared the disease course in the house finch, American goldfinch (Carduelis tristis) and house sparrow (Passer domesticus) after inoculation into the conjunctival sac with M. gallisepticum, and also the degree to which the three species were infectious to other naive house finches. Severity of clinical signs was least in house sparrows, intermediate in American goldfinch and the highest in house finch. House sparrows were only mildly infectious to naive house finches for a short time, whereas American goldfinches remained infectious for up to 49 days post inoculation, although by then there were no physical signs of disease. We conclude that since American goldfinches can be infectious without showing any conjunctivitis, and since they often make long-distance movements, they might play an as yet unsuspected but important role in M. gallisepticum dynamics in house finches.

Isolation and identification of Caviibacter abscessus from cervical abscesses in a series of pet guinea pigs (Cavia porcellus).

An organism reported in the early literature to be a rare cause of cervical lymphadenitis in guinea pigs, Streptobacillus moniliformis, has been reclassified as Caviibacter abscessus We describe a series of sequential cases of abscesses in guinea pigs that were presented to our clinic from which the only agent isolated was a unique, serum-requiring bacterium. Discrete colonies were not detected in 6.5% CO2 or anaerobically on routine primary isolation media containing up to 5% whole sheep blood, with and without cysteine, vitamin K, and hemin supplementation after 7 days of incubation at 37°C. Based on subsequently determined growth requirements, the organisms were best described as serum-requiring, aerotolerant anaerobes. Colonies were detectable within 24 h at 37°C in an anaerobic atmosphere on a mycoplasma agar-based medium containing 10% pig serum and reached 3 mm in diameter within 3-5 days. Microscopic appearance consisted of small gram-negative rods and coccobacilli with occasional filaments. However, in direct smears from clinical specimens and from weak or dysgonic growth on plates incubated under suboptimal growth conditions (e.g., in 6.5% CO2), irregular rods with occasional small bulbous forms or numerous long wavy filaments were observed. All of the isolates generated unique spectral profiles similar to that of C. abscessus when examined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Phylogenetic analysis of partial 16S rRNA gene sequences showed that the isolates were identical to each other and shared 99.9% sequence identity with C. abscessus.

Microsatellite development suggests evidence of polyploidy in the social sponge-dwelling snapping shrimp Zuzalpheus brooksi.

We isolated and characterized 33 novel, polymorphic microsatellite loci from the social sponge-dwelling snapping shrimp Zuzalpheus brooksi. We screened all 33 loci in approximately 31 individuals from a population of Z. brooksi from the Florida Keys, USA and found an average of 16 alleles per locus. Approximately 25% of the loci showed more than two bands per individual, suggesting evidence of high gene duplication, or more likely, polyploidy, which is common in crustaceans. The 25 disomic loci had an observed heterozygosity of 0.57 (range = 0.03-1.00) and will be useful for studying the social organization in Zuzalpheus shrimp.

A complete species-level molecular phylogeny for the "Eurasian" starlings (Sturnidae: Sturnus, Acridotheres, and allies): recent diversification in a highly social and dispersive avian group.

We generated the first complete phylogeny of extant taxa in a well-defined clade of 26 starling species that is collectively distributed across Eurasia, and which has one species endemic to sub-Saharan Africa. Two species in this group-the European starling Sturnus vulgaris and the common Myna Acridotheres tristis-now occur on continents and islands around the world following human-mediated introductions, and the entire clade is generally notable for being highly social and dispersive, as most of its species breed colonially or move in large flocks as they track ephemeral insect or plant resources, and for associating with humans in urban or agricultural landscapes. Our reconstructions were based on substantial mtDNA (4 kb) and nuclear intron (4 loci, 3 kb total) sequences from 16 species, augmented by mtDNA NDII gene sequences (1 kb) for the remaining 10 taxa for which DNAs were available only from museum skin samples. The resulting mitochondrial gene tree embedded within a multilocus framework shows that the well-studied taxa S. vulgaris/unicolor are the sister lineage to the remaining members of the radiation, from which other relatively early lineages gave rise to forms that are now nomadic or locally migrant in Africa (Creatophora) and western Asia (Pastor). The remaining taxa form a clade with a complicated biogeographic history primarily in central and eastern Asia; this group contains a range of sedentary to highly migratory taxa, as well as widely distributed species and single-island endemics such as the highly endangered Bali myna (Leucopsar). Several groups of species in the genus Acridotheres have low magnitudes of within-group divergence and likely diversified via their respective colonization of islands. The taxonomy of this entire group has remained highly volatile over the past century; we propose dividing these 26 species among 11 reciprocally monophyletic genera (Acridotheres, Poliopsar, Temenuchus, Sturnornis, Leucopsar, Gracupica, Agropsar, Pastor, Creatophora, and Sturnus).