Lisa ends up adopting a lot of animals.
The animal joke actually was rather amusing, but it is a joke that has never been played out extensively as Homer or Bart's stupidity have been done, which is a shame.
There could be an entire episode of how LIsa can't save all the animals but the show has never done it.
It's really getting very difficult to even focus on episodes of this show anymore, they are so repetitive and predictable.
The Simpsons is essentially doing what Scooby Doo or the Flintstones did, but while those two shows would leave the air and be retooled in a later incantation, The Simpsons has just made one very long run.
It seems unlikely that there will be a rediscovery of this show by future generations, because #1, the jokes will have to be explained when they are from movies and TV shows or dealing with current events, and #2, 'suggestive' material will be deleted left and right.