Abstract
An adult approximately seven to eight year old male white tipped reef shark (Triaenodon obesus) was reported to be inappetant on display in a public aquarium for a two week period. At this time staff reported seeing material protruding from the gill slit that resembled silicone. This shark shared the 100,000 gallon marine exhibit with four other white tipped reef shark, two nurse sharks (Ginglymostoma cirratum), two zebra sharks (Stegostoma fasciatum), one black tipped reef shark (Carcharhinus melanopterus), and two Crevalle jack (Caranx hippos), a large whip tailed stingray (Dasyatis americana) and an adult loggerhead sea turtle (Caretta caretta). The shark had been acquired from a nearby facility one year prior to reports of inappetence and no prior problems had been noted since arrival.
The shark was hand restrained to allow veterinary inspection and treatment. On inspection of gills and the oral cavity, oral ulcers were identified in the pharyngeal area and base of the tongue. Rough fibrinous type material was removed from the lesions. This material was thought to be sloughed mucosa from the pharyngeal region. No hemorrhage was noted in the ulcerated areas. Radiographs were non-diagnostic. The animal received sodium bicarbonate IV and ceftazidime IM.
In the weeks and months that followed, the animal was treated with antibiotic injections. The shark remained inappetant. However, several times this animal was seen grabbing at food but would promptly spit it back out and then stop feeding. This was a consistent behavior for many months. Due to concerns about the animal's health, condition and concern of the amount of handling required to care for this animal, it was relocated to a hospital holding tank off display.
Antibiotics, anti-inflammatory, and tube feeding were continued to varying degrees, in various combinations for over one year. Ascorbic acid was added to the feeding formula to prevent deficiency and aid in healing. Multivitamin supplements were added into the tube feeding formula. (Mazuri Vita Zu® Shark/Ray tablets, Mazuri Purina Mills, St. Louis, Mo) Several medical assessments were performed over the course of over one year. These assessments included endoscopy early on, confirming esophageal damage, ulceration, lacerations but of unknown etiology.
Histological evaluation of the sloughed/debrided material described mineralization with necrosis and bacterial colonization of the esophagus. Bacterial culture during one of the exams yielded Vagococcus salmonarum and another gram-positive organism not identified. Both organisms were sensitive to enrofloxacin, Clavamox, erythromycin, kanamycin and Romet. These organisms showed resistance to cephalosporins. Fungal culture was negative at this time. Antibiotic therapy was adjusted accordingly.
Various diagnostic procedures were performed with this animal under general anesthesia using MS222 at 90 ppm buffered with 180 ppm sodium bicarbonate. Supplemental sedation was also provided by increasing the dissolved oxygen in the water to 120%. Endoscopy was performed several times with this anesthetic regimen. Magnetic resonance imaging was performed at a local facility. This study identified what appeared to be a plastic disc shaped foreign body lodged in the dorsal esophagus. This object was not identified by manual palpation or endoscopy on follow up examination.
The most effective overall assessment method involved manual inspection of the entire affected area by the veterinarian placing an ungloved lubricated hand into the oral cavity and throat of the animal to palpate the affected region, debride sloughing tissue as needed and to locally medicate the lesions when possible. The animal recovered from these episodes each time without complications.
After several months of manual and histological evaluation, bacterial cultures and antibiotic therapy based on sensitivities, along with supplements, antifungal medication, pain management and tube feeding, this animal began to make a rapid recovery as the throat lesions healed. Almost one full year after the initial signs of inappetence in the animal were noted, the lesions in the throat were completely healed leaving normal mucosa in the esophagus (based on manual palpation).
After almost one full year of not being able to swallow, and not eating on its own this shark began to eat fish as an overjoyed staff watched. Once this animal started to eat small fish its appetite grew and this male soon developed a normal appetite and normal feeding behaviors. Overall its condition rapidly improved and veterinary care and monitoring was discontinued within a week of this male eating on its own. This shark was reintroduced into the display within one month of returning to normal feeding behavior.
Acknowledgements
The authors express gratitude for the multitude of staff and volunteers of The Florida Aquarium who devoted their time, energy and resources to the treatment and care of this animal. Thanks to marketing manager Tom Wagner for helping to get the message out about the plight of sharks. Most importantly thanks to White Tip #3 for being an amazing ambassador for his species and all shark species in the oceans.