An interesting fact is that Data created several hundred different food supplements for Spot. Another is that a genetic disease once caused Spot to mutate into a reptile (in the Season 7 episode Genesis).
Spot originally appeared as a Somali cat, but he later became a normal house cat. Spot also changed sex from male to female, giving birth to kittens in Genesis. These inconsistencies are more likely cases of bad continuity than some science-fiction plot.