When I first started playing and because I have Pets, I was surprised there were no strays or larger wild animals running around. Figured they were not coded into IP. After several games I found 2 horses and a foal on a residential lot owned by preinstalled Sims that came with the game. They were "stuck"... along with their owners on the tiny lot. I deleted them all and bulldozed the lot. No more Horsies. That is until I put the stable in and one of my sims bought a horse. I now have some wild horses running through town and some deer. Has anyone had this happen? They are not causing any problems or getting stuck. I was just surprised to see them and wondering why?

That's why animal control in Twallan's Register is invaluable. Wait until the horse tries getting up the ladder on the houseboat. Then you'll see what stuck REALLY means.

Do you have Register, by any chance? I had wild horses in IP and had to go into the mod to disable strays.

Eskie and shadedgrey... I do have Register and will use it as soon as they become a problem. I'm still chuckling over thinking about a horse trying to get up the ladder on a houseboat! Thanks for responding!

Hah, do the horses really try going up the ladders?

I believe that Isla Paradiso has no wild horses (or tourists) out of the box, but if you install Register, it enables them (and tourists) by default... can use it to turn them off too though. Pretty sure Twallan confirmed that somewhere; and it matches what I noticed, running modless for a week after IP's release and then updating NRaas.

However, even in the vanilla game any resident including houseboat dwellers can get the pet adoption scenario; that's probably what happened to the OP. They'll get a map tag saying pets are available to adopt, and get a couple of parent pets and a baby. Could be cats, dogs or horses :/ I've seen a few horses that wound up on boats this way, and yes I think it's silly

Isla Paradiso has no deer or raccoons, but wild horses are still possible there.

Register! That explains it. Thanks Srikandi. I thought it might have been because I put the Equestrian Center in my game. And, you are correct, they can also be turned off in Register. Thanks!