Abstract

In early 2019, a geriatric (>20 years old), male, cownose ray (Rhinoptera bonasus) was reported for concerns about progressive weight loss. On initial exam, the animal was in thin body condition (BCS 3/9), and bloodwork showed significant hyperglycemia (416 mg/dL). In spite of supportive care, weight loss and hyperglycemia both progressed rapidly, and within 2 months of initial presentation the animal had lost 25% bodyweight, with a blood glucose of 893 mg/dL. Other diagnostics, including complete blood count, plasma chemistry, and coelomic ultrasound, were non-specific or within normal limits. With concurrent profound hyperglycemia and severe weight loss, the decision was made to attempt insulin therapy. An isophane insulin suspension (NPH) was selected due to availability and dosing volumes and was administered at 0.2 U/kg of bodyweight via intramuscular injection in the pectoral fin. Serial blood glucose curves over the course of several weeks showed progressive, controlled reduction of plasma glucose levels to below 250 mg/dL, while simultaneously tracking improvements in body condition, weight gain, and reduction in appetite. Following more than 6 months of treatment, the ray remains stable and is managed with insulin injections on an every 2–4-week basis. Retrospective analysis of related parameters from this individual and non-diseased conspecifics includes fructosamine, thyroid hormone, insulin levels, and insulin antibody testing.

Acknowledgements

The author would like to thank The Florida Aquarium veterinary technical staff, Ashley and Sarah, for processing so much blood and being otherwise all-around amazing. Thanks also to the aquarium’s FINS team who take care of these and other incredible animals every day.

*Presenting author