Thestrals are commonly referred to as dark omens. They are associated with misfortune, sadness, and even death. These claims are understandable (especially from those that cannot see and/or interact with the Thestrals), but they are misinformed claims nonetheless.

The Ministry of Magic considers Thestrals to be dangerous creatures. Because of the Thestrals carnivorous behavior - alongside their heightened sense of smell regarding blood - many believe they will attempt to attack and kill on sight. This is not true.

The Ministry of Magic does allow Thestrals to be kept, bred, and tamed. However, proper permissions must be given by the Ministry before this is allowed, and this practice is still highly discouraged. Hogwarts was given permission to raise a herd of tame Thestrals by the Ministry. The Thestrals at Hogwarts are incredibly loyal and even assisted in the Battle of Hogwarts.

Due to International Statute of Wizarding Secrecy, Thestrals are technically illegal to use as transportation. It is a direct breach of the law. It is also discouraged - and in some cases, illegal - to own Thestrals in areas not protected from Muggles because of the International Statute of Wizarding Secrecy.

Abusing and neglecting Thestrals is also a punishable action. Though the Ministry considers them dangerous, they are also living creatures. Abuse and neglect of a Thestral can lead to a hearty fine - or even time in Azkaban, depending on the severity.