Cats should not be given anti-estrus powder for their entire lives. Anti-estrus powder is a type of hormonal medication, and long-term use can harm a cat's health. Specifically:
1. Damage to the immune system: Long-term use of anti-estrus powder can damage a cat's immune system, reduce its immunity, and make it more susceptible to bacterial and viral infections.

2. Endocrine disorders: Anti-estrus powder can affect a cat's hormone secretion, leading to endocrine disorders, which may in turn cause a series of reproductive system problems.
3. Infertility: Long-term use of anti-estrus powder may lead to infertility in breeding cats.
Therefore, for the sake of the cat's health, it is not recommended to use anti-estrus powder for a long time.