Atypical Histiocytosis in Red Squirrels ( Sciurus vulgaris )

Cutaneous Histiocytosis in an Eastern Gray Squirrel (Sciurus carolinensis)

A free-ranging Eastern gray squirrel (Sciurus carolinensis) was presented for ulcerated cutaneous masses at the base of both pinnae in July 2021. Diagnosis of cutaneous histiocytosis was achieved by histologic and immunohistochemical examination of one excised mass and supported by spontaneous resolution of the contralateral mass before the squirrel's release.

Head arteries of the red squirrel (Sciurus vulgaris)

The red squirrel (Sciurus vulgaris) is a medium-sized rodent protected in most of Europe. The present study aimed to investigate and describe the arterial vascularization of the head of the adult red squirrel. In the study, 48 specimens of adult red squirrels were used. The first preparation method used in the study was corrosion casting using a stained solution of the chemo-setting acrylic material injected into bilateral common carotid arteries resulting in corrosion castings of the vessels on a bone scaffold. The second method was injecting liquid-stained latex into both common carotid arteries. It resulted in a stained arterial vessel on fixed soft tissue preparations. The main vessels providing blood to the head were paired with common carotid arteries that divide into external and internal carotid arteries. The internal carotid artery passes into the stapedial artery. After giving its branches, the stapedial artery exits the cranial cavity through the sphenofrontal foramen and enters the orbit. The suborbital and the mandibular regions were supplied by the maxillary artery, linguofacial trunk, and their branches. Description of the detailed anatomy of the head arteries in red squirrels may contribute to establishing diagnostic and treatment protocols for wildlife rehabilitation centers, which may be crucial since red squirrels are endangered by the spreading of invasive Eastern gray squirrels (Sciurus carolinensis) in Europe. It may also contribute to veterinary care for other members of the Sciuridae family kept as pets.

DIAGNOSING AND CATEGORIZING LEPROSY IN LIVE EURASIAN RED SQUIRRELS (SCIURUS VULGARIS) FOR MANAGEMENT, SURVEILLANCE, AND TRANSLOCATION PURPOSES

The presence of Mycobacterium lepromatosis and Mycobacterium leprae in Eurasian red squirrel (Sciurus vulgaris, ERS) carcasses throughout the British Isles, and leprosy as a disease, have recently been reported using histological and molecular diagnostic methods. In 2016, the first longitudinal study of ERS affected by leprosy was initiated. One of the main challenges was the reliable diagnosis of leprosy in live ERS, which is important for (a) welfare and case management and (b) surveillance or pretranslocation screening efforts. We explored diagnostic methods ranging from detailed clinical assessment and informative categorization of observed lesions, thermal imaging, serology (antiphenolic glycolipid-I antibody [αPGL-I] detection) to molecular methods (polymerase chain reaction [PCR]). For PCR the ear was established as the optimal sampling site. Based on the experiences from this 2-yr study we propose an objective categorization system for clinical lesions and a diagnostic framework for the combination of the diagnostic tools we found to be effective in live ERS: clinical assessment, αPGL-I serology, and PCR. Thermal imaging did not offer additional information for leprosy diagnostics in ERS. We propose an amended definition of leprosy lesions in ERS as "skin areas of local hair loss, in which a firm-rubbery, glossy swelling develops, that may ulcerate" and standardized terminology for describing ERS leprosy status. The information presented forms the basis of a consistent, reliable diagnostic and reporting system for leprosy cases in ERS.