Thanks Engram, I was sure I was way under the limit. At the time it happened I had 2 adult sims (pregnant mom), 1 teen and the 2 critters. Then Sarah had her pups and the trouble began. The pup didn't really "disappear" so to speak. I was able to follow it (one of the times) and it seems that it was being called to leave the lot; it went through rabbit hole

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I knew the anticipation thing was a little far-fetched but I couldn't figure out why it corrected after I used the cheat file. Now I hope the families I gave the pups away to don't have issues.
The problem seemed to have been solved but I haven't played that house lately. I will keep an eye out as you suggest.
