Gasoline is a mixture of the alkanes and unlike many chemicals, can be stored for long periods and transported without problem. It is only when ignited that it has enough energy to continue reacting. This property makes it difficult for alkanes to be converted into other types of organic molecules.
Recovery from being spayed is usually around 10 days. My kitten was back to her usual self in three days but it took 10 days for the incision to heal enough for the stitches to come out.
The Humane Societies and Shelters tend to spay and neuter once a dog or cat weighs two pounds or more. The primary reason this is done so early is that, though there may be health costs to the pet, the overall balance of saved lives outweighs the individual health concerns. It's the 'Greater Good' concept.