Pets such as cats and wolves do not teleport to the player before a chunk is unloaded.

This can happen before using commands such as /tp or /home (the latter being from EssentialsX) or when a player is moving quickly via horse or boat. The latter is much more noticeable when exploring new territory and new chunks are being generated and much more of an issue as it can be harder to locate where the pet stopped following you.

Ideally, before a chunk unloads the server should teleport the pets to the player before unloading the chunk (assuming the pet meets the TP requirements of course).