# First Assessment of Oral Iron Chelator HBED Increases Iron Excretion in Black Rhinoceros (Diceros bicornis minor)

## TL;DR

An oral iron chelator called HBED increases iron excretion in black rhinoceros, offering a potential treatment for iron overload disorder.

## Contribution

This study is the first to demonstrate the efficacy of the oral iron chelator HBED in black rhinoceros.

## Key findings

- HBED administration increased urinary iron excretion in black rhinoceros compared to control treatment.
- One rhino experienced a hemolytic event after stopping treatment but fully recovered.
- HBED showed potential for safely aiding iron excretion in black rhinos under human care.

## Abstract

Black rhinoceros under human care develop iron overload disorder (IOD) which is associated with negative health consequences. Management of IOD involves minimizing iron into the body with diet and pulling iron out through either large-volume blood collection or a specialized iron binder known as a chelator. A cross-over study design in which three black rhinoceros were dosed for 10 days with the oral iron-specific chelator HBED resulted in increased urinary iron excretion compared to the control treatment. While all rhinos remained healthy during testing, one individual had a hemolytic event after stopping treatment, but she fully recovered. Tapering of the HBED dose before ending treatment would be recommended to avoid this complication. Overall, the chelator showed promise in aiding iron excretion in critically endangered black rhinos under human care.

Black rhinoceros (Diceros bicornis) face threats to survival due to poaching in the wild and an incomplete understanding of preventive health monitoring under human care. Black rhinos under human care develop iron overload disorder (IOD) which is associated with predisposition to other disease, compromised immune function, hemolytic crisis, and death. Management of IOD is challenging but has been mitigated in some cases with dietary intervention and phlebotomy and documented through serum biomarker evaluation. Chelation therapy to reduce iron is rare in rhinos partially because of limited product availability and route of administration. An iron-specific chelator HBED (N,N’-Di(2-hydroxybenzyl)ethylenediamine-N,N’-diacetic acid) was investigated for oral use in southern black rhinos (n = 3) after successful testing was performed with equids as a model. Using a cross-over design, we tested the efficacy of short-term HBED administration. HBED was dosed at 40 mg/kg body weight for 10 days and resulted in increased urinary excretion of iron but unaltered fecal iron excretion in rhinos compared to control trials. Two rhinos maintained blood chemistry and cell distribution considered normal for the species. The third rhino experienced a hemolytic event after stopping HBED administration in the same time frame and at the same dose as the two conspecifics but fully recovered. Careful monitoring and tapering the drug at the completion of treatment is warranted, especially if the rhino’s iron load is considered high. HBED’s potential to induce iron excretion safely, as well as prevent excessive dietary iron uptake, may significantly benefit the black rhino population under human care.