Immersion anaesthesia in goldfish (Carassius auratus) with three concentrations of alfaxalone.

OBJECTIVE: To evaluate the anaesthetic effects of three different alfaxalone doses to induce anaesthesia in goldfish. STUDY DESIGN: Prospective, randomized, clinical study. ANIMALS: Thirty goldfish undergoing skin scraping, gill examination and stool collection. METHODS: Each fish was transferred to an individual 4 L induction tank and randomly allocated into one of three groups (n = 10), in which alfaxalone was administered at concentrations of 6, 7 or 9 mg L-1. The depth of anaesthesia was evaluated by approach reaction, equilibrium, opercular movement and reaction to tactile stimuli. Sedation, light anaesthesia, surgical anaesthesia and recovery times were recorded. Data were analyzed with analysis of variance. A p value <0.05 was considered significant. RESULTS: Surgical anaesthesia was achieved in all fish. Goldfish induced with alfaxalone 7 and 9 mg L-1 showed a mild excitement phase. Time to sedation of the 6 mg L-1 dose (5.89 ± 0.40 minutes) was significantly longer compared to the 7 mg L-1 (3.97 ± 0.40 minutes) and 9 mg L-1 doses (3.94 ± 0.40 minutes). Times to light anaesthesia and surgical anaesthesia of the 9 mg L-1 dose (7.65 ± 1.04 and 9.60 ± 1.84 minutes, respectively) were significantly faster compared with those of the 6 mg L-1 dose (13.79 ± 1.04 and 19.75 ± 1.84 minutes, respectively) and the 7 mg L-1 dose (13.55 ± 1.04 and 21.24 ± 1.84 minutes, respectively). No significant differences were recorded in recovery time. Cessation of opercular movement was recorded in two fish induced with 7 mg L-1 and in two induced with 9 mg L-1. No mortality occurred. CONCLUSIONS: and clinical relevance Alfaxalone is a reliable agent for immersion anaesthesia in goldfish. Immersion in water containing 6 mg alfaxalone L-1 provided smooth induction of anaesthesia, and no obvious side effects were encountered. Higher doses shortened induction time and caused respiratory depression and excitatory movements.

Cytology of a seminoma in a koi (Cyprinus carpio): a rapid diagnostic tool.

Koi(Cyprinus carpio) is an ornamental variety of common carp frequently kept as pets. Given their long lifespan, neoplasia, albeit uncommon, may occur in these animals, and only a few studies have faced their cytological diagnosis. In the present case, a koi carp was referred to the clinicians due to coelomic swelling. The carp underwent surgery, which revealed an enlargement of both testes. Testicular samples were cytologically and histologically examined. The lesion was diagnosed as a seminoma since it was composed of round, large, atypical, and often multinucleated cells with round central nuclei and moderate cytoplasm. These tumors had the same appearance as seminomas in mammals and should be considered among differential diagnoses when coelomic swelling occurs in koi carp. Seminomas in koi carp are diagnosed histologically, but cytology, a rapid and cheap exam executable in all veterinary clinical facilities, could be a relevant preliminary diagnostic tool that may influence the entire diagnostic process.

Peripheral Nerve Sheath Tumors Resembling Human Atypical Neurofibroma in Goldfish (Carassius auratus, Linnaeus, 1758).

Skin spindle cell tumors (SSTs) frequently occur in fishes, with peripheral nerve sheath tumors (PNSTs) being the most commonly reported neoplasms in goldfish. However, distinguishing PNSTs from other SCTs is not always possible when relying exclusively on routine cytological and histopathological findings. Therefore, the aim of this study is to characterize six skin nodules, resembling atypical neurofibromas in humans, found in six cohabiting goldfish (Carassius auratus), and to determine a minimal subset of special stains required to correctly identify PNSTs in this species. Routine cytology and histopathology were indicative of an SCT with nuclear atypia in all cases, with randomly distributed areas of hypercellularity and loss of neurofibroma architecture. Muscular and fibroblastic tumors were excluded using Azan trichrome staining. Alcian blue and Gomori's reticulin stains revealed the presence of intratumoral areas of glycosaminoglycans or mucins and basement membrane fragments, respectively. PAS and PAS-diastase stains confirmed the latter finding and revealed intra- and extracellular glycogen granules. Immunohistochemistry displayed multifocal, randomly distributed aggregates of neoplastic cells positive for S100 protein and CNPase, intermingled with phosphorylated and non-phosphorylated neurofilament-positive axons. Collectively, these findings are consistent with a PNST resembling atypical neurofibroma in humans, an entity not previously reported in goldfish, and suggest that Azan trichrome staining, reticulin staining, and immunohistochemistry for S100 protein and CNPase represent a useful set of special stains to identify and characterize PNSTs in this species.