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This study aimed to describe the specific localization and anatomical pattern of 24 feline lymphomas of the nervous system for which the immunophenotype was identified by immunohistochemistry investigations to support the potential specific correlation between subtypes and anatomical patterns. In total 10 tumors affected the spinal cord, eight the brain, four the peripheral nerves, one involved both the brain and the spinal cord, and one simultaneously the brain and the optic nerves. Twenty two tumors were primary lymphomas. The affected animals were 8 years of mean age. Tumors developed as an extra-axial mass (11 cases), intra-axial mass (six cases), leptomeningeal lymphomatosis (three cases), and neurolymphomatosis (five cases). One of them expressed both leptomeningeal lymphomatosis and neurolymphomatosis patterns. Two intra-axial brain lymphomas showed an angiotropic pattern. The optic chiasm was the most involved site for neurolymphomatosis. Immunolabeling was performed using anti-CD3, CD20, CD79a, PAX5, MUM-1, CD56, and anti-CD44 antibodies. In total, 12 tumors consisted of B cell lymphomas, and six of T cell lymphomas, two cases were double-reactive lymphomas while two cases consisted of non-B non-T lymphomas. B cell lymphoma affected animals of 6.4 years of mean age, while the T cell lymphoma affected older animals (mean age of 11.1 years). Extra-axial tumors mainly consisted of B cell lymphomas (8/11). Neurolymphomatosis expressed different immunophenotypes, and the B cell phenotype was the most prevalent in the optic chiasm. Two leptomeningeal lymphomatoses expressed T cell immunophenotype. For the first time, plasmacytoid differentiation was found for angiotropic lymphoma and neurolymphomatosis. All the cases, except one, were CD56-negative. CD44-expression confirmed a common malignant potential for all the anatomical patterns of the nervous system lymphoma in cats. Immunophenotype of feline lymphoma of the nervous system and its potential association with specific anatomical patterns should be strongly required in the diagnostic workup and clinical approach to this tumor especially when its primary origin is confirmed.

West Nile virus (WNV) and Usutu virus (USUV) are mosquito-borne flaviviruses that have been associated with neurological diseases in humans and wild birds. Wild bird rescue centers are potential significant hot spots for avian infection surveillance, as recognized in the Italian Integrate National Surveillance Plan for Arboviruses. Here we report the results of a post-mortem active monitoring study conducted from November 2017 to October 2020 on animals hosted in five wild bird rescue centers of Central Italy. Five hundred seventy-six (n = 576) wild birds were tested by real-time polymerase chain reaction (RT-PCR) for the presence of WNV or USUV RNA fragments. No birds tested positive for USUV RNA (n = 0; 0.00%). Evidence of WNV RNA (Ct value = 34.36) was found in one bird (n = 1; 0.17%), an adult little grebe (Tachybaptus ruficollis subsp. ruficollis), that tested WNV positive in December 2019. This study highlights the strategic role of wildlife rescue centers in monitoring both the introduction and circulation of avian emerging zoonotic diseases. In addition, the presence of WNV during the cold season evidences the possible role of birds in overwintering mechanisms in the Italian territory and requires further investigations.

The vestibular system includes different anatomical structures and physiological pathways. In the first part of this chapter, we will briefly introduce the main anatomical constituents, i.e., vestibule, semicircular canals, vestibular ganglia and nerve, vestibular nuclei, flocculo-nodular lobe of cerebellum and other structures in the brain stem. In the second parts, we will discuss the pathways generated by signals transduced by vestibular structures. Briefly, the bony labyrinth is lined with the endolymph-containing membranous labyrinth, showing two chambers (utricle and saccule) and three semicircular canals (horizontal, anterior, and posterior). Each canal contains a receptor organ called crista ampullaris, whereas receptor organs of both utriculus and sacculus are called otolithic macula. All the information transduced by receptors travels through the vestibular nerve fibers and reachs the vestibular nuclei in the pons and medulla oblongata. The axons originated here supply various CNS areas, e.g., the spinal cord, oculogyric nuclei, the reticular formation, and the cerebellum. Vestibular receptors respond to accelerations of the head in space, providing direct information about its rotations (receptors of semicircular canals), orientation with respect to gravity and linear movements (receptors of otolithic maculae). Semicircular canals are excited by rotational accelerations, converted into rotational velocity signals by the mechanical structure of the canal. Each labyrinth is excited by ipsilateral head rotation, both labyrinths are excited by purely forward or backward rotation. The utricular macula lies horizontally, whereas the saccular macula is placed vertically. When the head is still and held erect with respect to gravity, the utricular macula is not stimulated, and tilts from the erect posture will excite utricular afferents. Conversely, the saccular macula is strongly stimulated when the head is erect, and little or not when the head is lying on either side. Vestibular signals (ipsilateral rotational head velocity, head tilt, or equivalent linear acceleration) assist balance: the vestibulocervical reflex excites neck muscles via the medial vestibulospinal tract to oppose head tilt, and vestibulospinal reflexes excite ipsilateral limb extensors via the lateral vestibulospinal tract to oppose body tilt.