Hydrocephalic fur seal undergoes brain surgery at Tufts

Ziggy Star is now home at Mystic Aquarium, recovering from her procedure at Cummings School of Veterinary Medicine

Veterinarians from Cummings Veterinary Medical Center at Tufts University and Mystic Aquarium prepare Ziggy Star, an adult Northern fur seal, for brain surgery. Photo courtesy of Mystic Aquarium.

A neurosurgical team at Cummings School of Veterinary Medicine at Tufts University has successfully performed a first-of-its-kind brain surgery on a female adult Northern fur seal in an attempt to address her worsening neurologic condition. Ziggy Star is recovering well at her permanent home at Mystic Aquarium in Mystic, Conn.

Ziggy was first seen at the Henry and Lois Foster Hospital for Small Animals at Cummings Veterinary Medical Center at Tufts University in September for a progressive condition that was causing severe neurologic episodes, difficulty moving, reduced training response, and cluster seizures. An MRI revealed an accumulation of cerebral spinal fluid in the brain—hydrocephalus.

Mystic Aquarium took in Ziggy approximately four years ago after she was found stranded on the California coast and deemed non-releasable by the federal government. At the time, she had an MRI that showed some neurologic abnormalities. She received treatment, but her symptoms continued to progress at a concerning rate, with the seizures emerging more recently.

“The MRI taken recently by our team showed that the brain was disappearing due to the excess fluid, and it was significantly worse than the last study four years ago,” said Ane Uriarte, DVM, Diplomate of the European College of Veterinary Neurology. “After discussion with Mystic’s veterinary team, we determined the best option to prevent further deterioration of the brain and to improve Ziggy’s symptoms was to surgically place a shunt to drain the excess fluid, relieving some of the pressure on the brain.”

While the procedure couldn’t reverse damage caused to the brain by excess fluid, if successful, it could stop the progression of Ziggy’s condition, improving her quality of life, level of responsiveness, and mobility.

Unable to find documented cases of hydrocephalus being surgically managed in pinnipeds, veterinarians relied heavily on their experience treating the condition in other animals, combined with extensive review of the skeletal structure of the fur seal to determine where to enter the skull and place the shunt.

The team present on the day of the surgery included veterinary anesthesiologists, neurosurgeons and zoological medicine specialists from Cummings Veterinary Medical Center, as well as zoological medicine specialists from Mystic Aquarium who serve as Ziggy’s primary veterinarians. Ziggy’s trainers helped to keep her calm and comfortable throughout transport and recovery. Mystic Aquarium brought in a boarded anesthesiologist who specializes in marine mammals. A marine mammal’s “dive reflex” can often lead to alterations in heart rate, blood pressure, and respirations when under anesthesia, which can make anesthesia more challenging than with a dog or a cat.

The surgical procedure involved placing a shunt catheter through the skull and into the brain. The catheter was then positioned underneath the skin through the neck and passed down to Ziggy’s abdomen. A valve controls the flow of excess cerebral spinal fluid from the brain to the abdomen, where the body absorbs it. Post-surgery, the veterinary team confirmed that the shunt was placed correctly via CT scan.

Ziggy had a slightly prolonged recovery after the procedure due to seizure activity that was successfully managed. She was transferred back to Mystic Aquarium once she was stable.

Ziggy is currently living in an off-exhibit habitat at Mystic Aquarium, where she is being monitored through her recovery and rehabilitation.

“We continue to monitor Ziggy very closely,” said Jen Flower, DVM, MS, DACZM, chief clinical veterinarian at Mystic Aquarium. “She is showing marked progress daily; eating a full diet; moving well within her habitat and showing normal swim patterns. No additional seizures have been noted post-operatively.”

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