Abstract

Koi (Cyprinus carpio koi) are common pet fish kept in outdoor ponds. There are many cases of chronic spinal disorders in koi, mainly caused by suspected congenital, nutritional, or environmental (i.e., lightning strikes) influences.^1-3 Corrections to these cases have been attempted by physical therapy, relocation, and stabilization surgery.⁴ However, in the case of sudden spinal trauma, these cases present suddenly, often causing great alarm and distress to the fish’s owner.

Koi fish are bred from brightly colored common carp (Cyprinus carpio). Their bodies are made up of a collection of red (slow-twitch) and white (fast-twitch) muscle fibers, which can provide short bursts of speed to evade predators or catch prey.⁵ Koi are also prey animals and make easy pickings for common backyard predators, including large fish-eating birds (i.e., blue heron), raptors (i.e., red-tailed hawk), large cats (i.e., bobcat), river otters and even bears. It is up to koi owners to provide as much protection as possible to their animals, but this will vary on the owner, season, and location of the pond. When startled by a possible predator attack or a perceived one, koi will spook and put on a short burst of speed to escape. Unfortunately, in small, confined ponds, this can have disastrous consequences when a koi comes up against a solid wall.

Three recent cases that presented to our mobile aquatic veterinary practice involved koi with suspected wall-related trauma. All three koi presented with sudden loss of swimming ability and laying on the bottom of their ponds. Fish were gently removed from their pond and placed in a solution of pond water plus 80 mg/L MS-222 and 80 mg/L sodium carbonate for 10–15 minutes. During this time, a physical examination was performed, including skin mucus and gill biopsies plus two-view radiographs (dorsoventral and right lateral).⁶ Two of the three fish received radiographs while still submerged underwater to limit stress on the spinal column from the fish being out of water. All biopsies and physical exams were unremarkable, but all three sets of radiographs showed signs of various compression trauma of the vertebral bodies.

Treatment varied for the three case examples, depending on the availability of follow-up care and changes in behavior and body position from the initial presentation to our veterinarian. The first case received one injection of meloxicam (0.1 mg/kg IM) and one injection of antibiotic (enrofloxacin 22.7 mg/ml 2:1 with sterile saline ICe). This fish recovered within 2 weeks to normal activity but re-presented with similar symptoms 2 months later. This fish was euthanized without being examined again for the presence of the same or another injury. One koi received no treatments, given that they were already showing signs of marked recovery. The third koi received one injection of antibiotic (enrofloxacin 22.7 mg/ml 2:1 with sterile saline ICe) and three injections of meloxicam (0.1 mg/kg IM). Both fish have gone on to make complete recoveries.

*Presenting author

Literature Cited

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