Pets are a big issue for both landlords and tenants. They can also cause a big problem between one tenant and another tenant if the animal isn't particularly well-behaved.
If you love your pet and want to avoid a problem, this is what you need to keep in mind:
Your lease controls your agreement with your landlord
If your lease says "no pets," it means "no pets." You can't rely on the word of a resident manager that pets are tolerated despite what the lease says. Don't sign a lease forbidding pets if you have one.
Make sure that you retain a copy of any lease that does permit pets. If your landlord changes, you may need it to prove your right to have the animal on the property.
If your pet is also a service animal, make sure that you provide the landlord with documentation
Service animals are given considerable leeway under the law if they're trained to help with a disability. However, there's been a rising problem with "fake" service animals. People can go online and get a quick certification for their pet, then use that certification to claim all the exemptions real service animals are due -- including the right to live in residences that normally forbid pets.
If your service animal is trained to assist you, provide your landlord with documentation of your disability and documentation of your animal's training -- not just the certification. Detail exactly what your pet does to assist you.
Don't allow your animal to create problems
If you have a dog, make sure that you keep the animal on a leash when you're in the hallways or other common areas of your building. If your dog is potentially aggressive, consider the use of a muzzle.
You also need to control your pet's general behavior. Keep your pet quiet and make sure that you promptly clean up any messes. That can keep you off the neighbors' radar and stop complaints before they start.
If you believe that a landlord is illegally trying to force you to get rid of your pet, an attorney who handles landlord/tenant disputes can explain your rights and help you try to resolve the issue.
Source: The Humane Society, "Information for Renters with Pets," accessed April 12, 2018