Pitbulls and other dangerous breeds will require risk insurance at a higher premium and will open you up to legal problems if the harms someone. 

A dog on a restricted breed list? 

If you do, then you can only charge for your actual out-of-pocket losses due to the tenant breaking the lease, plus reasonable advertising fees, normally.Google the state where the property is, and "landlord duty to mitigate damages," to find out if you can keep the money if they bail.You can't in CA, but I think you can in FL and other states, and even those states have some rules that say - but you can't take possession of the property, etc.  

Then find the best mentor or expert you can in that kind of investing.

To make matters worse, one is a Scottish Deer Hound, a huge breed.

@Kryssy Griffin  If the insurance bans certain breeds, then regardless of her reason she can't have it. 

@Randy Lehey we filter based on breed and weight of the dog.

My agent (with Allstate) says their policies exclude any dog with a known bite history, but no specific breed restrictions.The agent strongly encouraged me to require tenants to carry their own renter’s policy that includes a minimum $200,000 liability.

For the liability aspect, obtain  a renters insurance policy which covers the breed of dog you have.

Karma is rewarding you for doing the right thing and taking care of your folks.There is no cap on how many of your and your spouse's combined four parents you can do this for, but if you try using it multiple times be prepared to prove to a skeptical underwriter that mom did indeed actually move in, and that you are not collecting rent from her (according to your accurate Schedule E).Also, because this is a principal residence per Fannie's definition, and not a second home or investment property, that means it can in theory be an 11th financed property.