Canine idiopathic orbital inflammation: A case series of four affected dogs (five orbits).

PURPOSE: In humans, idiopathic orbital inflammation (IOI) is a diagnosis attributed to benign, inflammatory orbital conditions without identifiable local or systemic cause. We describe the clinical signs, imaging and histopathological findings, management and outcome of four dogs diagnosed with IOI. METHODS: Multicentric retrospective study. RESULTS: A total of four dogs (five orbits) of three different breeds (three cases were English Springer Spaniels [ESS] or ESS-cross) and ages ranging from 3 to 12 years were included. Initial presenting signs were unilateral and included exophthalmos, enophthalmos, globe deviation, thickening and protrusion of the third eyelid and conjunctival hyperemia. Computed tomography and magnetic resonance imaging identified heterogeneous space-occupying, contrast-enhancing orbital lesions in all cases. Sparing of the retrobulbar space was detected in four of five orbits. Histopathology revealed mixed inflammatory infiltrates of lymphocytes, plasma cells, and histiocytes. Immunohistochemistry was performed in two cases highlighting the presence of histiocytes and lymphocytes, predominantly T cells. Resolution of clinical signs was achieved in two cases managed with oral immunosuppressant medication (corticosteroids alone or combined with cyclosporine or azathioprine), one went into spontaneous remission, one resolved with topical corticosteroids, and one underwent exenteration. Recurrence occurred in two cases within 15 months of initial diagnosis and required further immunosuppressant medication. One case developed signs in the contralateral orbit within 8 months of presentation. CONCLUSIONS: IOI is an uncommon condition in dogs. Its diagnosis relies on the combination of advanced imaging and histology. As in humans, it appears that spontaneous remission and recurrence may occur requiring long-term immunosuppressant medication.

Vertebral giant cell tumour of bone in a domestic shorthair cat.

Case summary: A 10-year-old male neutered domestic shorthair cat was presented with a 5-month history of progressive non-ambulatory paraparesis. Initial vertebral column radiographs revealed an L2-L3 expansile osteolytic lesion. Spinal MRI showed a well-demarcated, compressive expansile extradural mass lesion affecting the caudal lamina, caudal articular processes and right pedicle of the second lumbar vertebra. The mass was hypointense/isointense on T2-weighted images, isointense on T1-weighted images and had mild homogeneous contrast enhancement after gadolinium administration. MRI of the remaining neuroaxis and CT of the neck, thorax and abdomen with ioversol contrast revealed no additional neoplastic foci. The lesion was removed by en bloc resection via a dorsal L2-L3 laminectomy, including the articular process joints and pedicles. Vertebral stabilisation was performed with titanium screws placed within L1, L2, L3 and L4 pedicles with polymethylmethacrylate cement embedding. Histopathology revealed an osteoproductive neoplasm composed of spindle and multinucleated giant cells without detectable cellular atypia or mitotic activity. On immunohistochemical evaluation, osterix, ionised calcium-binding adaptor molecule 1 and vimentin labelling were observed. Based on the clinical and histological features, a giant cell tumour of bone was considered most likely. Follow-up at 3 and 24 weeks postoperatively demonstrated significant neurological improvement. Postoperative full-body CT at 6 months showed instability of the stabilisation construct but absence of local recurrence or metastasis. Relevance and novel information: This is the first reported case of a giant cell tumour of bone in the vertebra of a cat. We present the imaging findings, surgical treatment, histopathology, immunohistochemistry and outcome of this rare neoplasm.

The effect of BCG vaccination on macrophage phenotype in a mouse model of intranasal Mycobacterium bovis challenge.

In order to develop improved vaccinations against tuberculosis, it is essential to understand the effect of vaccination on the immune response, and to overcome the mechanisms by which mycobacteria regulate this immune response. In this study, we examine the effect of intradermal vaccination with Mycobacterium bovis bacille Calmette-Guèrin on macrophage phenotype following intranasal challenge with virulent Mycobacterium bovis. Preserved lung tissues used in the present study were obtained from a previous vaccination trial in BALB/c mice. Vaccinated mice showed less extensive pulmonary lesions along with a significant decrease in bacterial lung burden when compared to control mice. Immunohistochemical markers of classically activated macrophages (iNOS) and alternatively activated macrophages (Arg1, FIZZ1) were applied to lung sections. Vaccination led to a statistically significant decrease in the number of Arg1+ macrophages. The presence of macrophages that expressed Arginase 1 in pulmonary lesions was much smaller than the presence of macrophages expressing iNOS. The low presence of Arg1+ macrophages induced by vaccination may be caused by Th1 polarization and may reduce alternative activation of macrophages, with an overall more effective intracellular killing of bacteria.

Rapid postoperative recurrence of a cranial multilobular tumor of bone in a young dog.

Although resection of multilobular tumors of bone can be associated with a good prognosis and long disease-free intervals in dogs, osteosarcomatous transformation should be considered a cause for rapid recurrence of clinical signs.