Tail regeneration reduction in lizards after repetitive amputation or cauterization reflects an increase of immune cells in blastemas.

Lizards are key amniote models for studying organ regeneration. During tail regeneration in lizards, blastemas contain sparse granulocytes, macrophages, and lymphocytes among the prevalent mesenchymal cells. Using transmission electron microscopy to examine scarring blastemas after third and fourth sequential tail amputations, the number of granulocytes, macrophages, and lymphocytes increased at 3-4 weeks in comparison to the first regeneration. An increase in granulocytes and agranulocytes also occurred within a week after blastema cauterization during the process of scarring. Blood at the third and fourth regeneration also showed a significant increase in white blood cells compared with that under normal conditions and at the first regeneration. The extracellular matrix of the scarring blastema, especially after cauterization, was denser than that in the normal blastema and numerous white blood cells and fibroblasts were surrounded by electron-pale, fine fibrinoid material mixed with variable collagen fibrils. In addition to previous studies, the present observations support the hypothesis that an increase in inflammation and immune reactions determine scarring rather than regeneration. These new findings verify that an immune reaction against mesenchymal and epidermal cells of the regenerative blastema is one of the main causes for the failure of organ regeneration in amniotes.

Rostral mandibular fracture repair in a pet bearded dragon (Pogona vitticeps).

CASE DESCRIPTION A 2-year-old male bearded dragon (Pogona vitticeps) was evaluated because of a traumatic mandibular fracture. CLINICAL FINDINGS An open comminuted fracture of the rostral aspect of the right mandible was evident, with a fragment of bone exposed and dorsally displaced. Whole-body radiography revealed no evidence of additional injury. Other findings were unremarkable, except for moderate anemia (PCV, 19%). TREATMENT AND OUTCOME The fracture fragments were stabilized with 2 crossed 36-gauge interfragmentary wire loops. An external fixator device was fashioned from four 25-gauge needles inserted at alternating angles through the fracture fragments; plastic IV fluid line tubing filled with dental acrylic was used as a connecting bar. One day after surgery, the lizard had regained its typical activity level and appetite. Body weight was measured and the external fixator was inspected 1 week after surgery and monthly thereafter. Three months after initial injury, the fracture was stable, radiography revealed bony callus formation at the fracture site, and the external fixator was removed. Recheck radiography performed 5.5 months after initial injury revealed complete osseous union of the fracture fragments, and the interfragmentary wires were removed. CLINICAL RELEVANCE Surgical management of the traumatic comminuted mandibular fracture in this bearded dragon by means of a combination of internal and external fixation resulted in complete healing of the mandible and restoration of function. Management of this complicated fracture was achieved with the aid of readily available and inexpensive supplies in a clinical setting, which may be useful to other clinicians in the management of similar cases.

Morbidity and Mortality of Reptiles Admitted to the Australian Wildlife Health Centre, Healesville Sanctuary, Australia, 2000-13.

Medical records of 931 reptiles admitted to the Australian Wildlife Health Centre, Healesville Sanctuary, Healesville, Victoria, Australia, from 2000 to 2013 were reviewed to determine the causes of morbidity and mortality. Thirty-nine species were presented; the most common were the common long-neck turtle (Chelodina longicollis; n = 311, 33.4%), the eastern bluetongue lizard (Tiliqua scincoides; n = 224, 4.1%), the blotched bluetongue lizard (Tiliqua nigrolutea; n = 136, 14.6%), and the lowland copperhead (Austrelaps superbus; n = 55, 5.9%). Trauma was the most significant reason for admissions, accounting for 73.0% of cases. This was followed by not injured (11.7%), displacement (6.4%), snake removal (4.2%), human interference (3.1%), introduced species (1.1%), sick/diseased (0.2%), and illegal pet (0.2%). Within the category of trauma, impact with motor vehicle (41.0% of trauma cases) and domestic animal attack (33.2% of trauma cases) were the most common subcategories. Our results indicate that indirect anthropogenic factors are a significant cause of morbidity and mortality in Australian reptiles.

Compressive myelopathy of the cervical spine in Komodo dragons (Varanus komodoensis).

Cervical subluxation and compressive myelopathy appears to be a cause of morbidity and mortality in captive Komodo dragons (Varanus komodoensis). Four cases of cervical subluxation resulting in nerve root compression or spinal cord compression were identified. Three were presumptively induced by trauma, and one had an unknown inciting cause. Two dragons exhibited signs of chronic instability. Cervical vertebrae affected included C1-C4. Clinical signs on presentation included ataxia, ambulatory paraparesis or tetraparesis to tetraplegia, depression to stupor, cervical scoliosis, and anorexia. Antemortem diagnosis of compression was only confirmed with magnetic resonance imaging or computed tomography. Treatment ranged from supportive care to attempted surgical decompression. All dragons died or were euthanatized, at 4 days to 12 mo postpresentation. Studies to define normal vertebral anatomy in the species are necessary to determine whether the pathology is linked to cervical malformation, resulting in ligament laxity, subsequent instability, and subluxation.

Orthopedic radiography in exotic animal practice.

Radiographic examination of exotic animal species provides significant diagnostic information to the practitioner so long as attention is paid to positioning and radiographic detail and if variations in normal radiographic anatomy are contemplated. Fracture of pneumatic bones (humerus or femur) in avian patients often results in subcutaneous emphysema, much like an open fracture. If fracture alignment is anatomical, there is generally little callous formation visible in avian and reptile patients; however, if malunion occurs, then certainly callous can be visualized. Aggressive or excessive periosteal proliferation in exotic species often predicts osteomyelitis. Practitioners can increase their diagnostic capabilities and thereby decrease any preconceived anxiety by applying the same general interpretive concepts used in the radiography of more routine small animal patients and by evaluating the resultant radiographs in a systematic manner. With the exception of certain anatomical differences and alterations in response to injury, exotic animal species suffer the same types of orthopedic disease do dogs and cats.

Spontaneously occurring fractures of the spine in skeletally immature animals.

STUDY DESIGN: Twelve spontaneously occurring fractures of the spin in nine skeletally immature animals were investigated. OBJECTIVES: These fractures were analyzed radiographically, morphologically, and histologically. SUMMARY OF BACKGROUND DATA: The most commonly injured regions were the cervical and lumbar regions. Multiple-level fractures were noted in three specimens. METHODS: Morphologic and histologic examination invariably detected fractures in cases of spinal cord injury without radiographic abnormality. RESULTS: The end-plate physes and synchondroses were found to be the "weak links" for propagation of fractures. Radiographically benign-appearing ring apophyseal fractures were found histologically to propagate from the end-plate physis through the vertebral body via the contiguous neurocentral synchondroses. CONCLUSIONS: The observed morphologic and histologic fracture patterns should provide a better understanding of the probable comparable pathoanatomy of spine and spinal cord injuries in children.