Feline head and hind-limb lymphography using near infrared fluorescence with indocyanine green: an ex vivo anatomical study in 11 cats

Animal lymphatic system is a translational model for humans, nonetheless, previous researches have been conducted only on few canine cadavers and no studies included cats[1- 3] . Moreover, previous studies did not describe anatomical lymphosomes’ landmarks[1] . In this context the aim of this explorative study is to map the feline lymphatic system, focusing on head and hind-limb regions whose drainage is considered complex. Feline cadavers without neoplastic, surgical or traumatic lesion located at the anatomical region of interest were included. Topographical regions of head and hind-limb were defined based on bone landmarks. Indocyanine-green (ICG) was intradermally injected in each area. Massage and flexion-extension movements were performed to optimize the ICG migration. Near infrared fluorescence (NIRF) was used for lymphography and to guide nodal extirpation. Correspondence between detected lymphocentrum (LC) and those predicted by previous canine studies were recorded[1] . Eleven adult cats were included. All cats had body condition score <3/5 and skin thick <2 mm. One cat had pigmentated skin. A total of 16 hind-limb and 7 head regions were analysed. In 5/23 regions no LC was identified: 2 ears, 1 crural, 1 cranial-thigh, 1 finger- plantar. Six hind-limb cases drained to double lymphosome as reported in previous anatomical canine studies. In 5 cases the LC did not correspond to the expected lymphosome of those canine studies. Nineteen LCs were detected and 27 nodes extirpated. Median migration time, drainage length and nodal size were respectively 5 (1-30) min, 5 (0- 11) cm and 10 (5-22) mm Dipartimento di Scienze Veterinarie e dell’Allevamento – via dell’Università 6, 26900 Lodi – phdcourse.vas@unimi.it DOTTORATO DI RICERCA IN SCIENZE VETERINARIE E DELL’ALLEVAMENTO. The use of NIRF-ICG is feasible in feline cadavers with a low percentage of failure, probably due to cadavers’ storage and conservation, and thawing process. Anatomical landmark gives more accurate identification of the areas drained by an LC. A higher number of cases is needed to evaluate repeatability and predictability of lymphosomes.