Accessory Antler Growing From the Left Zygomatic Bone of a Male Rusa Deer (Rusa timorensis)

Area of Science:

• Veterinary medicine
• Zoology
• Developmental biology

Background:

• Antlers are unique to cervids (deer family) and are typically grown from pedicles on the frontal bones.
• Accessory antler growth, particularly from unusual locations like the zygomatic bone, is exceptionally rare in scientific literature.

Purpose of the Study:

• To report and describe a unique case of accessory antler growth from the zygomatic bone in a rusa stag.
• To discuss the potential causes and implications of ectopic antler development.

Main Methods:

• Case report of a single rusa stag (Cervus timorensis rusa).
• Gross examination of the skull and ectopic antler structure.
• Histological examination of the pedicle-antler junction (implied by maceration results).

Main Results:

• An accessory antler (5.4 cm) covered in velvet was found growing from the left zygomatic bone.
• The antler structure was attached via a pedicle originating from a bony socket.
• Detachment during maceration suggested a cartilaginous connection at the pedicle base.
• A possible second accessory antler was observed on the right brow but was destroyed.

Conclusions:

• This is the second reported instance of antler formation from the zygomatic bone.
• Accessory antler growth is likely triggered by periosteal trauma.
• All deer skull membrane bones may have the potential for accessory antler formation under strong, abnormal stimulation.