Definitely sounds recessive based on what we know so far. It's still probably best perform all the necessary outcrosses before writing anything in stone. There are 2 possible scenarios here...
1st) Both adult leopards are homozygous recessive for the same mutation at the same loci.
2nd) One of the adults is homozygous dominant, the other is normal.
Both of these scenarios will yield the same outward results in the F1 generation. They will be very different on the inside however. Scenario 1 will produce 100% homozygous recessive leopards, scenario 2 will produce 100% heterozygous dominant leopards. The quickest way to prove this out would be to outcross BOTH adults with unrelated stock. If BOTH subsequent litters contain all normal looking offspring then it's almost definitely simple recessive. Has this been done yet? It's always difficult to prove anything regarding mode of inheritance prior to achieving F2 status, but outcrossing BOTH parents would be a great place to start.
Great topic by the way! I've been wondering when us amazon folks would begin to show more interest in genetics. After all they are the most polymorphic boid species on the planet and their future genetic morph potential is virtually unlimited. Perhaps more so than balls & boas combined! We just all need to start paying better attention to the results of our litters to hopefully unlock some of this potential. Hats off to the Urban Jungles team for doing just that.
>>O.k. I just got off the phone with Danny of Urban Jungles and he says it is simple recessive. They bred a leopard to a normal and got all normal looking babies and they bred leopard to leopard and got all leopards.....so it would be recessive.