Hi Kelly,
Although cots are available at most Walt Disney World resort hotels at a cost of $15/night, Animal Kingdom Lodge is not one of the properties which have them.
Bed rails are indeed available at not extra cost, and should be requested in advance on your reservation.
You may also find it useful to know that complimentary Pack 'n play Playpens are also available in all rooms which provides another sleeping option for your toddler.
In addition, one of a limited number of cribs may be available for your stay. This again, should be added as a note to your reservation in advance, and requested again upon arrival for check-in since they are given out on a first come, first served basis. There is also an outside company, recommended by Disney, through whom you can rent infant and toddler necessities for your stay. Visit their website all-about-kids.com or contact them at 1-800-728-6506 to inquire about products and rates.
If you'd like to contact me again and let me know what room type you're staying in at Animal Kingdom, and whether you're at Jambo house or Kidani Village, I may be able to assist you with some further suggestions to ensure your toddler has a safe and comfortable place to sleep during your stay!
Did you know that Walt Disney World rents strollers right in the parks? I've attached a link to the
Stroller Rentals information for you in case you'd prefer this option to bringing a stroller from home.
Thanks for visiting me at the Moms Panel with your question.
Wishing you a Magical time at Walt Disney World Kelly!
Kirsten