Let me start by telling you that I am a landlord and a dog lover. My wife and I enjoy doing dog rescue and at this time have seven dogs that we are training and fattening up for suitable adoption. SO I am no dog hater BUT I also owned a MH Park for many years and more than once had to deal with "bootlegged" pets. This is a difficult part of your business... You dont want to exclude a dog that is serving a legally defined service task, or appear to be the heartless landlord.
BUT It sounds like the tenant is abusing the ADA law to defy the terms of her rental agreement. A service dog is not primarily a protection dog. A service dog is a type of assistance dog, specifically trained to help people who have disability or disabilities ...
Under the Americans with Disabilities Act (ADA), privately owned businesses that serve the public, ...requires these businesses to allow people with disabilities to bring their service animals onto business premises in whatever areas customers are generally allowed. BUT is this a legal service dog??? what tasks is this dog trained for??
The ADA defines a service animal as any guide dog, signal dog, or other animal individually trained to provide assistance to an individual with a disability. If they meet this definition, animals are considered service animals under the ADA
What if a service animal barks or growls at other people, or otherwise acts out of control?
You may exclude any animal, including a service animal, from your facility when that animal's behavior poses a direct threat to the health or safety of others. For example, any service animal that displays vicious behavior towards other guests or customers may be excluded. You may not make assumptions, however, about how a particular animal is likely to behave based on your past experience with other animals. Each situation must be considered individually.
Source -
http://www.ada.gov/qasrvc.htm
If you have further questions about service animals or other requirements of the ADA, you may call the U.S. Department of Justice's toll-free ADA Information Line at 800-514-0301.
You must enforce the park rules or others residents will be looking for exclusion from the rules they dont like AND you could be open to liability claims. You must handle this swiftly and legally Confer with your state manufactured housing association, and visit with a lawyer. Learn the specifics of your state's service dog rules.
Although a number of states have programs to certify service animals, you may not insist on proof of state certification before permitting the service animal to accompany the person with a disability. Let a lawyer contact the resident and in view of her violation of her rental agreement, insist on written certification of her need and the dogs service capabilities.
However it turns out BE SURE the lawyer gets a signature from the resident that shows her understanding of liability and your release from liability should the dog hurt anyone. If you dont take swift action and anyone is injured, yours will no doubt appear to be the biggest pockets on the horizon. Your legal costs could be considerably higher defending yourself in court and your insurance will either go sky high or be unattainable.
Talk is cheep and not confirmable in court. Document every move with certified letters so in the event that you do end up defending yourself and your business you are prepared