In most countries, it is legal to use a GPS tracker on a pet. However, it is always a good idea to check local laws and regulations. Some areas may have specific rules about the use of GPS trackers on pets, and it is important to comply with these regulations to avoid legal issues.
Additionally, it is important to consider the privacy of others when using a GPS tracker on a pet. This can be an issue if you have a dog walker, or if you leave your pet with friends or in pet hotels during trips. Some people may feel uncomfortable if they believe their location is being tracked without their consent. It is important to use pet surveillance devices responsibly and to respect the privacy of others while ensuring the safety and well-being of pets.