Editorial Type:
Article Category: Case Report
 | 
Online Publication Date: Feb 02, 2021

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

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Page Range: 224 – 231
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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.

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Figure 1.
Figure 1.

Photographic image of the tongue of an anesthetized 10-yr-old female blue-tongued skink. The proximal part of the tongue is pink, whereas the distal part of the tongue is dark blue.


Figure 2.
Figure 2.

(A) Computed tomography (CT) of the pharyngeal area sectioned at the level of the middle ear showing the reduced pharyngeal lumen (asterisk) and the narrowed auditory tube (arrowheads). (B) CT of a healthy blue-tongued skink at the same level. at, auditory tube; ph, pharynx; pp, paroccipital process; rp, retroarticular process; t, trachea; tc, tympanic cavity. (C) Transverse T2-weighted fast spin echo MRI image of the pharynx (ph) of a 10-yr-old female blue-tongued skink at the level of the middle ear (top) and caudally (bottom), showing hyperintense fluid accumulation (white arrow on both images) in the ventral aspect of the left tympanic cavity (tc) and ventrally in the right side of the pharynx at the esophagus entrance. Low signal-to-noise ratio is due to patient size and the presence of osteoderms. (D) Dorsal plane reformatted CT image of the caudal coelomic cavity with mineralized foci in bilateral kidneys (white arrow).


Figure 3.
Figure 3.

Endoscopic images of the pharynx of a 10-yr-old blue-tongued skink: general view of the pharynx (A) and biopsy site (B).


Figure 4.
Figure 4.

Histopathology lesion noted at the level of the vessels of the heart base. (A) Hematoxylin phloxine saffron stain and (B) Van Kossa stain: mineralized tissues appear black. Magnification, ×200.