I am pretty sure they are only allowed at certain camp sites. From allears
Does FW allow pets?
Yes. In fact, Fort Wilderness is the only pet friendly resort on Disney World property. Request a pet site when making reservations. Pets are allowed in Premium, Preferred and Full Hook-Up campsites in loops 1600 through 1900, 300, 700 and 800, but must be kept in those areas. Depending on the season and demand, Fort Wilderness might also temporarily designate certain loops as pet loops. There is an additional charge of $5 per day.