Vitamin D Toxicosis in a Blue-Tongued Skink (Tiliqua scincoides) Presented with Epistaxis and Tongue Discoloration

Abstract

A 10-yr-old intact blue-tongued skink (Tiliqua scincoides) of unknown sex presented for epistaxis and dyspnea. On physical examination, dysecdysis, necrosis of the tip of the tail, and a pink discoloration of the proximal third of the tongue were noted in addition to epistaxis, dyspnea, and tachypnea. Clinical pathology findings included marked polychromatophilia, moderate heterophilia with signs of toxicity, a regenerative left shift, and moderate hyperglycemia. Because of the suspicion of an infectious etiology, antibiotics were prescribed. Meloxicam was also administered without clinical improvement. Swelling of the pharyngeal area was noted on whole-body computed tomographic and magnetic resonance imaging. Oro-pharyngeal endoscopic-guided biopsies were performed under general anesthesia. Histology was consistent with moderate erosion and goblet cell hyperplasia. Plasma 25-hydroxyvitamin D3 concentration was 768 nmol/L and was interpreted as possible vitamin D toxicosis. Prednisolone was prescribed to enhance calciuresis and treat potential vasculitis, but the skink was ultimately euthanized. Histopathologic examination was consistent with vitamin D toxicosis. The diet of this skink mostly consisted of greens dusted with a supplement containing calcium and vitamin D3. This case report describes the challenges associated with antemortem diagnosis of a vitamin D toxicosis, even with current imaging techniques. It highlights that specific reference intervals should be established for 25-hydroxyvitamin D3 and ionized calcium concentrations in various reptile species. Clinicians presented with a blue-tongued skink displaying a pink tongue or tail necrosis should consider vitamin D toxicosis in their differential diagnosis.