In fish, ocular surgery may be warranted after trauma or because of advanced stages of infectious, inflammatory, or neoplastic disease. In some cases, particularly with invasive tumors, exenteration (ie, removal of the entire orbital contents-eye, extraocular muscle, fat, and connective tissue) is necessary. The surgical approach and technique for removing the eye in fish is relatively simple. The fish is anesthetized by immersion in an appropriate agent, is removed from the water, and the procedure, which often requires fine surgical instruments and a magnifying head loupe because of the small size of the eye, can be done within a few minutes. After the procedure the orbital socket can either be left open or packed with a waterproof paste. Parenteral antibiotics (eg, enrofloxacin 10 mg/kg) are administered immediately after surgery and continued for 10 days by immersion or in food. Postoperative analgesia is also recommended (eg, a single injection of butorphanol 0.4 mg/kg IM). Sodium chloride (1 to 2 g/L) added to the water after surgery helps to minimize wound infection and reduces the osmotic effects of exposed tissue in freshwater fish. Cases in which exenteration is being considered should be selected with care because of the poor postoperative survival rates. The procedure is useful for traumatic and noninvasive neoplastic lesions, but is less successful for other disorders-particularly uveitis, which is often associated with systemic disease.
COMMENTARY: Fish are predisposed to ocular disease because they lack eyelids and the cornea is in constant contact with the environment. Ocular diseases are relatively common in fish, and owners often do not notice a problem until it has advanced. This article provides a good overview of when and how to perform exenteration on fish. A step-by-step approach with adequate photographs helps aid practitioners in trying this relatively simple procedure. The author does add a caveat: Only a third of his cases survived for more than 6 months after the procedure. Of those, most were otherwise healthy and had localized noninvasive lesions or severe trauma to the globe. Nevertheless, this is a reasonable option for select cases.
Exenteration in fish. Wildgoose WH. EXOTIC DVM 9:27-31, 2007.