American curl kittens are born with straight ears at the beginning and then begin to curl after 48 hours. After four months the ears will no longer curl, the feeling of their ears should be hard and stiff to the touch at the base of the ear with flexible tips. (the cat's ear curls between 90 and 180 degrees) American curls are susceptible to ear infections because of the unique shape of their ears which tends to trap more wax inside (Signs of ear infections in cats include an unpleasant odor, discharge, redness, and irritation of the ear), this could lead to bacteria and yeast to grow in the ear and lead to ear infections. Veterinarian-approved cleaner can help lessen the percentage of getting an ear infection (Signs of ear infections in cats include an unpleasant odor, discharge, redness, and irritation of the ear)
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