Proposal of a putative necropsy technique for post mortem examination in Giant River Prawn (Macrobrachium rosenbergii)

Proposta de uma possível técnica de necropsia para exame post mortem em camarão-gigante-do-rio (Macrobrachium rosenbergii)

Crustacean production is a vital aquaculture activity in Brazil and worldwide, contributing to food security for various population groups. Quickly and accurately diagnosing emerging and re-emerging diseases poses a significant challenge to shrimp production. Even though several techniques can render a definitive diagnosis, the initial step involves identifying macroscopic lesions and collecting samples for testing. Standardizing a necropsy technique for shrimp is essential. This study aims to establish a necropsy protocol that can be applied orderly and systematically. Eight adult giant river prawn (Macrobrachium rosenbergii) specimens were used: six females and two males, with an average weight of 41 g ± 15 g, an average total length of 14.38 cm ± 1.64 cm, and an age of 6 months. The animals were euthanized using eugenol (100 mg/L) and potassium chloride (100 mg/100 g of body weight) and then subjected to hemolymph collection by ventral hemolymphatic sinus puncture. The specimens were initially examined externally and subsequently sectioned into cephalothorax and abdomen, each undergoing a dorsal incision along the midline to expose anatomical structures such as the intestine, heart, gonads, stomach, hepatopancreas, and nervous tissues. Out of the eight specimens evaluated, three exhibited alterations: absence of appendages, areas of erosion and melanization, and reduced exoskeleton hardness. The technique described by the authors enabled a thorough evaluation of these animals’ main organs and can be adapted to other shrimp species, considering anatomical variations and lesion sites.

INDEX TERMS:
Necropsy technique; prawn farming; macroscopy; invertebrates