Doublecortin (DCX) and neuronal nuclear protein (NeuN) can be used as immunomarkers of neuronal progenitor cells and mature neurons, respectively. Increased DCX immunolabeling has been associated with tumor invasion in human gliomas and anaplastic canine meningiomas. These immunomarkers have not been assessed in feline gliomas. Here we characterized the DCX and NeuN immunohistochemistry (IHC) profile in 11 feline gliomas (7 oligodendrogliomas, 4 astrocytomas). Immunolabeling was classified according to intensity (weak, moderate, strong), distribution of neoplastic cell immunolabeling (1 = <30%, 2 = 30–70%, 3 = >70%), and predominant location within the neoplasm (random or at tumor margins). DCX immunolabeling was strong in 6 cases, weak in 4 cases, and moderate in 1 case. The distribution of DCX immunolabeling was characterized as 1 (4 cases), 2 (4 cases), and 3 (3 cases). DCX immunolabeling occurred predominantly in astrocytomas, which had stronger immunostaining at the tumor margins. NeuN immunolabeling was absent in all cases. Our IHC findings are similar to those reported for DCX and NeuN IHC in canine gliomas. The increased DCX immunolabeling at tumor margins is similar to labeling in invasive human gliomas and anaplastic canine meningiomas.

A 4-year-old male neutered French Bulldog was presented for progressive paraparesis. At the onset of clinical signs 2 days prior, survey thoracolumbar spinal radiographs were completed which identified multilevel hemivertebrae without evidence of aggressive bony lesions. Despite management with non-steroidal anti-inflammatories, the dog's condition progressed prompting referral. Upon referral, the dog was ambulatory paraparetic with a moderate proprioceptive ataxia, had normal spinal reflexes in all limbs, and a cutaneous trunci reflex cut-off at the thoracolumbar junction. Over 12 hours, the dog progressed to paraplegia with intact nociception and loss of the cutaneous trunci reflex. When supported, the thoracic limb stride was occasionally short and choppy. A brief electrolyte panel, packed cell volume, total solids and blood smear with a manual platelet count were unremarkable. Magnetic resonance imaging (MAGNETOM Skyra 3T, Siemens, Erlangen, Germany) revealed a focal, left sided, intraparenchymal spinal cord lesion extending from C7 to T2 occupying approximately 95% of the spinal cord's cross-sectional area (Fig 1). MRI findings were consistent with varying stages of haemorrhage ranging from hyperacute to chronic with areas of central enhancement representing active haemorrhage. T2W images of the brain, acquired to rule out possible metastasis, were normal. Given the rapid progression, euthanasia was elected.Corresponding to the MRI, intraparenchymal spinal cord haemorrhage was confirmed on autopsy (Fig 1). Without evidence of a coagulation disorder, neoplasia, vascular anomaly, or other inciting cause grossly/histologically, the dog was diagnosed with a primary haematomyelia. This case provides a description of rarely reported haematomyelia in dogs and serves as the first description of confirmed primary haematomyelia to correlate the MRI sequence characteristics with pathology. FIG 1. Magnetic resonance images, gross findings, and H&E images. Details are provided in the online Supplementary material

Severe nasal Prototheca cutis infection was diagnosed postmortem for an immunocompetent cat with respiratory signs. Pathologic examination and whole-genome sequencing identified this species of algae, and susceptibility testing determined antimicrobial resistance patterns. P. cutis infection should be a differential diagnosis for soft tissue infections of mammals.

Herein we describe a rare case of systemic Listeria monocytogenes infection with concurrent pleural mesothelioma in a stray cat that was found dead and submitted for autopsy. Gross pathology changes consisted of thoracic clear yellow fluid admixed with suspended fibrin strands; clear-to-tan, variably sized, <3 mm diameter pulmonary nodules; and enlargement of the submandibular, retropharyngeal, and prescapular lymph nodes. Histologic changes consisted of extensive areas of suppurative inflammation and necrosis with mineralization that partially effaced the pulmonary parenchyma and lymph nodes. Random, distinct necrotic foci were present throughout the hepatic parenchyma. Extending from the pleura, within perinecrotic alveolar spaces, and infiltrating the submandibular, retropharyngeal, and prescapular lymph nodes were dense sheets of neoplastic epithelioid cells with moderate pleomorphism and occasional karyomegaly and multinucleation. Neoplastic cells exhibited immunolabeling for pancytokeratin AE1/AE3 and vimentin, consistent with pleural mesothelioma. Aerobic bacterial culture of lung yielded heavy growth of L. monocytogenes. Immunohistochemistry (IHC) for L. monocytogenes revealed clusters of bacteria in the lung, lymph node, and liver. Pathologic changes were consistent with systemic listeriosis, confirmed by bacterial culture and IHC, and concurrent pleural mesothelioma.

A seven-year-old male captive Tasmanian devil was euthanased after presenting with hindlimb ataxia and generalised muscle wasting. On necropsy, an irregular, cream-coloured, firm, 1 cm mass was detected on the dorsal surface of the left olfactory bulb. The mass was composed of pleomorphic neoplastic cells arranged in nests and lobules with occasional pseudorosette formation, and evinced invasion of underlying neural parenchyma. By immunohistochemistry, neoplastic cells were strongly positive for vimentin and cytokeratin AE1/AE3, variably positive for S-100 and neuron-specific enolase, and negative for calretinin, chromogranin A, synaptophysin, glial fibrillar acidic protein and neurofilament protein. Periodic acid-Schiff and Grimelius stains were also negative. Based on histopathological and immunohistochemical findings, the neoplasm was classified as an anaplastic meningioma.