Enforcement Rules of Animal Protection Article 10

The owner shall apply for the cancellation of the registration to the original authority within one month of the death of the animals referred to the Article 7 and Article 8.For the loss of the animals referred to the Article 7 and Article 8, the owner shall report the loss to the original authority within one month of such event. Animals having been reported as missing and not found within one year shall be deemed dead, and the registration of such animals shall be nullified by the registration authority.
中文原文 動物保護法施行細則第10條
依第七條、第八條規定辦理登記之動物死亡,飼主應自動物死亡之日起一個月內,向原登記機關辦理註銷登記。
依第七條、第八條規定辦理登記之動物遺失,飼主應自動物遺失之日起一個月內,向原登記機關辦理申報;已申報遺失之動物,於一年內未能尋獲者,視同死亡,原登記機關得逕行註銷。

English translation for reference only; the Chinese text prevails. Not legal advice.