actually, apple without the seeds is a great treat, I give it to my crew all the time... just avoid the seed. That is also true for dogs (apple = great treat for dogs, but seeds are a NO-NO!) other veggies and fruits like grapes, carrots, banana.... just avoid citrics... and do NOT give them in large quantities cause they high humidity causes diarrhea. If you are afraid about the quantities, you can buy a bag of dry fruits (with no sugar added) and give them those as treats, and they love them too. Also cherios can be given as treats and yogurt drops (sold at pet stores) are really fun for them.