New Landlord here with a question about dogs! (Supposedly mans best friend)

[Alex Burrows]

Hey everyone, I just purchased a triplex in Toronto.  Two of the units are tenanted and I am going to live in the other.  Its a detached home with a detached garage in the rear with a descent sized backyard.  Im a brand new investor and do not have any experience with being a landlord.  I am taking possession of the property this coming up Thursday.  

When I met my tenants last week, one of them asked if they could bring their dog from Ottawa to Toronto and keep it at the home.  Their current lease states "No Pets" however their lease ends in September.  She had asked me if she could bring her dog in September and I told her that I would get back to her with an answer once I am living there next week.  I am not 100% sure how I feel about it.  I think the only hesitation is that I don't want the dog to be noisy, wreck anything or have dog poop all over my lawn.  The tenant said that the dog is well trained, 4 year old mixed lab and doesn't bark.  What should I do?  I was thinking of implementing a $25 monthly pet fee and/ or a security deposit?  Is there any terms I can put in the new lease incase the dog is a big problem? i.e. -Noisy, loads of poop, etc.

Thanks for your advice in advanced. 

Alex