abstract
Over a five month period, five adult cuttlefish (Sepia officinalis) housed at an oceanarium died with coccidial branchitis and enteritis. All were exhibited in an indoor 1900 liter tank of artificial sea water (Instant Ocean, Aquarium Systems, Mentor, OH 44060) with crushed shell substrate. The life support components included ultraviolet light sterilization, protein skimming, and chemical (carbon), mechanical (filter floss), and biological filtration. The diet of the adult cuttlefish consisted of frozen cut capelin pieces with occasional live penaeid shrimp or fiddler crabs. Water quality parameters over the five month period were within normal limits, except occasional elevations of nitrites from 0.002 to 0.167 ppm. All five mortalities occurred after the arrival and introduction of two new adult cuttlefish from another facility. No previous reports of coccidiosis in cuttlefish had been reported at the oceanarium.
On gross post-mortem examination, the only changes seen (in three of five cuttlefish) were small, often coalescing, granulomas in the walls of the intestinal tract. On histopathologic examination all five cuttlefish had granulocytic branchitis with few to numerous intraepithelial coccidian macrogametes. Granulomas in the wall of the intestinal tract contained sporocysts, and large numbers of variably degenerate granulocytes. These lesions were often exacerbated by a gram-negative bacterial infection (bacterial etiology not yet identified). In the intestinal mucosa, intraepithelial macrogametes and microgametes were occasionally seen. Identification of the coccidian is pending, but the organism is morphologically consistent with Aggregata spp.
Prior to placing juvenile cuttlefish on exhibit, parasite screening of the new population was attempted. Due to the difficulty in assessing the intestinal wall of a cuttlefish pre-mortem, a gill biopsy was performed on a sentinel animal to check for coccidians. The cuttlefish was anesthetized in a bath of four liter tank water, 400 ml magnesium chloride stock solution (made with one liter deionized water and 75 g magnesium chloride) and 20 ml ethyl alcohol (Absolut Vodka, Ahus, Sweden, 80 proof, 40% alcohol). Four grams of Trizma buffer (Sigma-Aldrich, St. Louis, MO 63103) was added for pH stabilization of the anesthetic water, and an air stone was used to oxygenate the bath. After 5-10 minutes, the cuttlefish could be manually restrained without inking or resistance for endoscopy. Gilling rate ranged from 24 to 60 per minute. A 2.7 mm avian laparoscope was introduced between the mantle and siphon, and passed until the gills were visualized. Endoscopic biopsy forceps were used to collect a gill tip sample for wet mount and histopathology. Tissue quality, both size and architecture, was excellent for evaluation; no coccidians were found. After 30 minutes of anesthesia, the animal recovered uneventfully. Three weeks later, the animal was euthanized to perform complete histopathology. No coccidians were found in the gill or enteric tissue. This gill biopsy method appears to be an effective collection technique for diagnostic pre-mortem gill samples in cuttlefish.
acknowledgements
The authors wish to thank the Seas Aquarium Department, Jane Capobianco, Charlene Burns, Erin Culpepper, Samantha Gallow, Vicki Sikorski, Dr. Scott Terrell, and the Disney's Animal Programs veterinary technicians for their assistance with these cases.