Abstract
Hydrocephalus is a common neurological disorder in all species and ages that is characterized by enlargement of the cerebral ventricles and often increased intracranial pressure. There are two types of hydrocephalus: acquired hydrocephalus which is the type of hydrocephalus that develops at birth or in adulthood and is typically caused by injury or disease and congenital hydrocephalus which is present at birth and may be caused by events that occur during fetal development or because of genetic abnormalities. At present, treatment is limited to surgical diversion (shunt treatment) of cerebrospinal fluid (CSF) from the cerebral ventricles to alternative absorption sites or to endoscopic third ventriculostomy (ETV) with or without choroid plexus cauterization (CPC). Functional outcomes are problematic, with residual neurological and cognitive deficits prevalent in 25–80% of patients.4 A primary barrier to progress in improving treatments for hydrocephalus in larger species is a lack of large animal models of this disorder to elucidate the multifactorial pathophysiology of hydrocephalus and evaluate the effects of suboptimal therapeutic treatments.5
Reports of hydrocephalus in cetaceans are still uncommon with a very high mortality in either form.1,2 Overall, most of the literature involving hydrocephalus in cetaceans is diagnosed from stranded animals2,3 or stillborn calves’1 postmortem. A few clinical cases of hydrocephalus in cetaceans under managed care have also occurred, but none have survived. A common cause of hydrocephalus in cetaceans is neurobrucellosis, but it also can be caused by meningitis, brain trauma, hemorrhage, or tumors.2,3
This is the case of Lotus, a 14-year-old, female bottlenose dolphin that was born at her current home at Island Dolphin Care in the Florida Keys. This is a not-for-profit dolphin therapy organization providing life-changing solutions for children and families with special needs, as well as veterans living with mental and physical challenges. In early May 2023, Lotus began to have decreased energy, seemed slightly “wobbly,” and had a mildly decreased appetite. Routine diagnostics included blood, ultrasounds, microbiome assessments, cytology of sputum, feces, and gastric fluid. Essentially, all parameters were within normal range. Treatment included antibiotics, antifungals, GI support, and fluids. A CT performed 10 days from initial clinical signs revealed bilateral moderate hydrocephalus. All other results of thorax and neck were WNL. In a previous CT performed in 2016, her brain ventricles were normal. We began intense infectious disease testing, and all results were negative. We discussed anesthesia, MRI, CSF taps, etc. with leading anesthesiologists and neurologists, and she was deemed too high risk for these diagnostics overall at this stage. Steroids were implemented along with increased GI support to avoid causing gastritis. Over the next few weeks, her CNS clinical signs worsened to include stiff swimming gait, swimming off balance, jerky movements, and wobbly when “head up” to eat. The social dynamics of the group of dolphins changed and she spent more time apart from the group. We performed a follow up CT with contrast in mid-July which revealed persistent but decreased moderate generalized hydrocephalus with dilation and rounding of the lateral ventricles. We began weaning steroids and discontinuing antibiotics. We continued antifungal medications. Then, another CT performed in early November revealed worsening of the fluid buildup in her ventricles. However, her clinical signs were extremely mild revealing that her nervous system and brain seemed to be adjusting to her abnormalities.
In late January 2024, Lotus started exhibiting signs of lethargy and inappetence. At this time, she had been receiving low-dose prednisone and voriconazole and had been fairly stable for months. One day later, Lotus had what appeared to be a grand mal seizure and passed away. To date, this is the only known case of hydrocephalus in a cetacean that has survived this long.
Cytology of her CSF revealed branching fungal hyphae and conidia (Candida albicans), but these were not found in her brain. She also had a pyometra, which was diagnosed via ultrasound the day of her death. To date, this is the only known case of hydrocephalus in a cetacean that has survived for 8 months.
Acknowledgements
The authors wish to thank Luke Bullen, executive director of Island Dolphin Care and the trainers and staff at IDC for their unwavering dedication to Lotus’s case and commitment to give her the best quality of life.
*Presenting author
Literature Cited
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