Orthopedic Diagnostic Imaging in Exotic Pets

Osteohistological analysis of metatarsals reveals new information on pathology and life history of troodontids from the Campanian Dinosaur Park Formation, Alberta, Canada

Troodontidae is a family of small-bodied theropods known predominantly from Asia but are comparatively scarce in North America. In the Dinosaur Park Formation (DPF) of Alberta, Canada, they are known predominantly from isolated material, precluding taxonomic and ontogenetic precision for this clade. Previously never sampled histologically within the DPF, here we attempt to fill in gaps in our knowledge about the life histories of the clade in this formation by histologically surveying metatarsals, which are among the most abundant and identifiable troodontid elements in the DPF. We sampled 11 metatarsals (three metatarsal IIs, three metatarsal IIIs and five metatarsal IVs) of varying sizes and included three pathological individuals to describe the microanatomy of both healthy and pathological metatarsals, determine the ontogenetic status of each element and graph their pattern of growth. Osteohistology reveals that troodontid metatarsals grew and remodelled asymmetrically within the cortex, ceasing growth and remodelling primarily along articular surfaces and entheses. Pathological individuals ranged from displaying features of response to localised stress (chronic callus formation and avulsion/chip fracture) to extreme modification in response to trauma and inflammation at the distal joint. Only the latter appeared to be related to overall growth, suggesting the condition either developed early and stunted growth or another underlying cause was responsible for both the stunted growth and the resulting pathological features observed. Overall, tracking the growth of the specimens reveals that there are at least two growth trajectories within the DPF differentiated by the timing of major growth spurts and growth plateaus. Whether this represents sexual dimorphism, taxonomic diversity, or another form of variation warrants further investigation.

Diagnostic Approach Using Computerized Tomography and Successful Surgical Resolution of a Palatine Luxation and Entrapment in a Blue and Yellow Macaw (Ara ararauna)

A seven-month-old male blue and yellow macaw (Ara ararauna) was presented with an inability to move the maxillary beak after flying into a clothesline. Unsuccessful attempts to reduce the beak were performed, first by the owner at home and later within the same day by the referring veterinarian under general anesthesia. The patient was referred for assessment and treatment 5 days later. A palatine luxation and entrapment with a possible fissure of palatine bone was suspected based on history, a physical examination, and radiographic imaging. Another unsuccessful attempt to manually reduce the beak was performed under general anesthesia. A computed tomography (CT) scan was scheduled to evaluate the skull further. Rostrodorsal displacement and entrapment of the palatine bone on the rostral edge of the interorbital septum in the mesethmoid region were identified. In addition, the CT images provided useful information for the veterinary team to rule out other skeletal abnormalities, rendering a significantly more detailed evaluation of the skull bones before surgical intervention. Surgery was performed after the previously published pin insertion method over the dorsal aspect of the palatine bone. Pressure in the ventral direction was then applied on the pin while simultaneously further hyperextending the maxillary beak to unhook the palatine bone from the interorbital septum. The present case report describes an in vivo diagnosis of palatine luxation and entrapment in a blue and yellow macaw by means of a CT scan and successful surgical resolution.

Assessing Pubic Symphysis Evolution in Guinea Pigs (Cavia procellus): Insights From Computer Tomography on Primiparous and Non-Breeding Females

In guinea pigs (Cavia porcellus), dystocia is a common occurrence. Several factors have been identified in the literature, including the ossification of the pubic symphysis following failure to breed before 9-12 months of age. The objective of this study was to investigate the ossification of pubic symphysis and its evolution during growth in two groups of females. The first group consisted of non-breeding females, while the second group comprised females introduced to breeding at 4-6 months of age. Twelve pairs of sows were selected for comparison, with one non-breeding and one breeding sow in each pair. Symphysis width and tissue density were assessed using micro-computed tomography. Measurements included the distance between the acetabula, width and bone density of the pubic symphysis. Serial computed tomography scans were performed on each sow over several months, both before and after parturition. The results revealed a significantly higher symphysis width in females that had bred. In addition, symphysis ossification was absent in both breeding and non-breeding sows, contrary to previous descriptions of this species. Therefore, dystocia in guinea pigs may not be attributable to ossification of the pubic symphysis.

Cory's Shearwater (Calonectris borealis): Exploring Normal Head Anatomy through Cross-Sectional Anatomy, Computed Tomography and Magnetic Resonance Imaging

Cory's shearwater, or Calonectris borealis, stands out as a symbolic figure in the world of seabirds, playing a crucial role in marine ecosystems globally. Belonging to the Procellariidae family, it is singularized by its imposing wingspan and intricate migration patterns connecting it to various regions from the North Atlantic to the Pacific. Its role in the marine food chain, specialized diet and adaptation for nesting in the Canary Archipelago underscore its ecological importance. However, Cory's shearwater also faces important threats, such as the invasion of foreign species, highlighting the need for its conservation. Among the conservation issues, studies on its biology, the main threats it faces and its normal anatomy are essential to preserve marine biodiversity. Additionally, a variety of imaging techniques, such as computed tomography and magnetic resonance, facilitates the understanding of the bird's neuroanatomy and opens future research possibilities in comparative neuroscience. Moreover, this approach proves particularly relevant given the increasing attention these seabirds receive in environments such as zoos, rehabilitation centers and their natural habitat, where veterinarians play a crucial role in their care and well-being.

Cross Sectional Anatomy and Magnetic Resonance Imaging of the Juvenile Atlantic Puffin Head (Aves, Alcidae, Fratercula arctica)

The Atlantic puffin is a medium-sized seabird with black and white plumage and orange feet. It is distributed mainly along the northern Atlantic Ocean, and due, among other reasons, to human activities, it is in a threatened situation and classified as a vulnerable species according to the International Union of Conservation of Nature (IUCN). In this study, we used a total of 20 carcasses of juvenile Atlantic puffins to perform MRI, as well as anatomical cross-sections. Thus, an adequate description of the head was made, providing valuable information that could be helpful as a diagnostic tool for veterinary clinicians, who increasingly treat these birds in zoos, rehabilitation centers, and even in the wild.

Tracheal stenosis in a yellow-crowned parrot (Amazona ochrocephala) due to diffuse ossification and osteopetrosis of tracheal rings

Tracheal luminal stenosis can cause clinical respiratory distress in wild birds. We describe a case of tracheal stenosis due to diffuse ossification with osteopetrosis of tracheal rings in a yellow-crowned parrot (Amazona ochrocephala) with a history of chronic respiratory distress and death after development of marked dyspnoea. An ante-mortem radiographic examination revealed that the tracheal rings were radiopaque and that there were multiple areas of osteopenic change in long bones. At necropsy, there was stenosis of the tracheal rings characterized by complete replacement of cartilage by thickened compact bone with osteopetrosis and bone necrosis. The clinical respiratory distress and death of the parrot were associated with tracheal luminal stenosis due to thickening of the tracheal rings by diffuse ossification with osteopetrosis.

Chronic fracture and osteomyelitis in a large-bodied ornithomimosaur with implications for the identification of unusual endosteal bone in the fossil record

Paleopathological diagnoses provide key information on the macroevolutionary origin of disease as well as behavioral and physiological inferences that are inaccessible via direct observation of extinct organisms. Here we describe the external gross morphology and internal architecture of a pathologic right second metatarsal (MMNS VP-6332) of a large-bodied ornithomimid (~432 kg) from the Santonian (Upper Cretaceous) Eutaw Formation in Mississippi, using a combination of X-ray computed microtomography (microCT) and petrographic histological analyses. X-ray microCT imaging and histopathologic features are consistent with multiple complete, oblique to comminuted, minimally displaced mid-diaphyseal cortical fractures that produce a "butterfly" fragment fracture pattern, and secondary osteomyelitis with a bone fistula formation. We interpret this as evidence of blunt force trauma to the foot that could have resulted from intra- or interspecific competition or predator-prey interaction, and probably impaired the function of the metatarsal as a weight-bearing element until the animal's death. Of particular interest is the apparent decoupling of endosteal and periosteal pathological bone deposition in MMNS VP-6332, which produces transverse sections exhibiting homogenously thick endosteal pathological bone in the absence of localized periosteal reactive bone. These distribution and depositional patterns are used as criteria for ruling out a pathological origin in favor of a reproductive one for unusual endosteal bone in fossil specimens. On the basis of MMNS VP-6332, we suggest caution in their use to substantiate a medullary bone identification in extinct archosaurians.

Geriatric Hedgehogs

African hedgehogs are susceptible to aging changes like those of other small exotic mammals. Common conditions of the geriatric hedgehog include heart disease, chronic renal disease, and dental/periodontal disease. Hedgehogs are unique in that they have an unusually short life span and a propensity for neoplasia. These 2 factors make it especially common for exotic animal practitioners to encounter geriatric hedgehogs affected by one of the many conditions outlined in this article.