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Fungal diseases, despite their low incidence in sharks and rays, are considered emerging diseases in this group of animals and can lead to high mortality rates despite treatment. The information available related to the treatment of fungal diseases in elasmobranchs is limited and is frequently based on the empirical knowledge provided by the professionals and clinicians working with these species. The use of azole antifungal drugs, especially voriconazole, has shown promise as a potential treatment option for fungal infections in elasmobranchs, with favorable outcomes in some registered cases. However, scientific knowledge regarding azole pharmacokinetics (PK) in fish remains limited, and despite the recent publication of a PK study with voriconazole in rays, there are still no published PK studies for azoles in sharks. In this study, voriconazole was administered at 4 mg/kg intravenously (IV) and intramuscularly (IM) to nursehound sharks (Scyliorhinus stellaris) (n = 6). Blood samples were collected before administration and at nine predetermined time intervals afterwards (0.25, 0.5, 1, 1.5, 2, 4,8,12, 24, and 36 h). Plasma concentrations were determined using a validated high-performance liquid chromatography (HPLC) method, and pharmacokinetic (PK) parameters were estimated using a non-compartmental model. The mean peak plasma concentrations (C_max) ± SEM after IM administration was 3.00 ± 0.23 µg/mL. The volume of distribution (Vd) after IV and IM administration resulted in 1.39 ± 0.09 L/kg and 1.50 ± 0.18 L/kg, respectively, showing no statistically significant differences between the two routes. Clearance (Cl) values were 0.12 ± 0.01 mL/min after IV administration and 0.29 ± 0.05 mL/min after IM administration. No adverse effects were detected during the study or four weeks after administration. These results support the administration of IV and IM voriconazole in sharks; however, additional studies on toxicity and pharmacodynamics are necessary. Moreover, further research on the susceptibility of fungal pathogens affecting elasmobranchs is needed to establish an optimal dosing regimen for IM voriconazole in the treatment of mycosis in sharks. Full article

The nursehound Scyliorhinus stellaris is a threatened shark species and its population in the Mediterranean Sea is declining. Programs for captive breeding and repopulation in marine protected areas (MPA) are being carried out. Unfortunately, pathogens may hinder conservation plans for this species. An impactful disease of marine animals, caused by the bacteria Photobacterium damselae, has been detected with increased frequency in recent decades in both farmed and marine animals. The aim of this work was to determine the cause of a disease outbreak in eight captive nursehounds that died after 18 months of captivity. Gross necropsy observations were indicative of a presumptive diagnosis of hemorrhagic septicemia. Histological and molecular techniques were performed, to diagnose the etiological agents that could be involved in their mortality. Phylogenetic analysis indicated the presence of P. damselae, identified as subsp. damselae by PCR-duplex, and Photobacterium swingsii in the analyzed captive nursehound Scyliorhinus stellaris. Full article

The complete mitochondrial DNA sequence of the Nursehound Scyliorhinus stellaris has been determined for the first time and compared with congeneric species. The mitogenome sequence was 16,684 bp in length. The mitogenome is composed of 13 PCGs, 2 rRNAs, 22 transfer RNA genes and non-coding regions. The gene order of the newly sequenced mitogenome is analogous to the organization described in other vertebrate genomes. The typical conservative blocks in the control region were indicated. The phylogenetic analysis revealed a monophyletic origin of the Scyliorhininae subfamily, and within it, two subclades were identified. A significant divergence of Scyliorhinus spp. together with Poroderna patherinum in relation to the group of Cephaloscyllium spp. was observed, except for Scyliorhinus torazame, more related to this last cited clade. A hypothesis of a divergent evolution consequent to a selective pressure in different geographic areas, which lead to a global latitudinal diversity gradient, has been suggested to explain this phylogenetic reconstruction. However, convergent evolution on mitochondrial genes could also involve different species in some areas of the world. Full article