Spayed & neutered pets still having offspring?

[commasplice]

Sooooo, in another of my games (thankfully not my rags to riches one), my sim's female cat who has been fixed keeps going off and coming back with kittens.

Bug? Birth control in the Sims is not 100% effective for pets? Something else?

[MrsFlynn]

This may be a bug.

[OPEN] [CD] Spayed cat gone into labor
https://answers.ea.com/t5/Bug-Reports/TO-ADD-CD-Spayed-cat-gone-into-labor/m-p/6463025#M53612