Another reason is liability and safety concerns. Many people are afraid of animals with sharp pointy teeth :)
A typical exception for allowing dogs and other animals are those animals know as "service" animals that care for thier owners, such as seeing eye dogs and "emotional support" companions.
There are quite often exceptions to rules. You could always put together a plea with your supporting documentation and present your argument.
I hope this helps. If you would like additional assistance with this or other rental properties, please feel free to contact myself or my assistant, Belinda.
407-545-6447 x 3005