Sim's Dog portrait causing game to crash

@TrueMathsHi!  That's so weird.  Are you okay with using cheats?  If so, then maybe you could try these steps. 

1. Play any other household and have them travel to the offending houehold's lot (hopefully one of the sims is at home).

EDIT: Woops!  Traveling requires clicking on the lot which brings up the portrait.  So, travel to a lot near the offending household, then you should be able to visit the household 's lot from there by clicking on their lot and choosing Visit Residence.  This will not bring up any portraits.
2. Turn on testingcheats, if you haven't already (ctrl+shift+c then type or copy/paste testingcheats on in the console that pops up in the upper left and type enter)
3. Turn on full edit (in the cheat console type or copy/paste cas.fulleditmode and type enter)

4. Shift+click on the dog or any other sim in that household
5. Find and select the Modify in CAS option
6. Once in CAS you should be able to delete the dog.

Hope this helps!

@JonaO703 This isn't possible because I can't mouse over the lot without the tooltip with the family CAS portrait/household info popping up and crashing the game.  Traveling to an adjacent house and choosing to "Travel to.." also crashes when trying to load into the affected family's lot.  A few minutes ago, I backed up my saves and my sims directory, installed MCCC for the first time, and trying to get into the family's CAS by using MCCC also caused a CTD.  Same when using "Edit in CAS" with shift+left click base game cheats when the bugged dog's owner is a guest at another sim's house.

@TrueMathsDo you have a way to get to where the dog is?  MCCC has an option to delete sims in the Sim Commands menu.  If you can get to the dog, click on it and select MCCC then Sim Commands, then Delete Sim.  You'll get a "are you sure?" pop up saying this will permanently delete the sim.

@TrueMaths 

Do you ever see the dog (not the owner) when you're in live mode?  And do you know its name?  I think there may be way to get rid of the dog without opening its portrait if you can find the dog out in the world in live mode.  MCCC has an option that allows you to kill a sim immediately in live mode by clicking on the sim directly and using the option.  No portrait involved.  But I don't know if it will work on pets as I have never tried doing that.  I don't play pets, so I've never had occasion to use it.  So, you might want to see if you can get rid of the dog that way.

And, are you sure it is a dog?  If you have Cottage Living, foxes still generate weird portraits in Manage Households and can cause problems.  They look fine out in the world but the MH portraits are not normal.  It could be one of them if it is not a dog.

Hope this helps.

@CGrant56I do know the dog's name. I have not been able to get the dog to show up by giving the neighborhood park the "Dog Friendly" lot trait.  Nuking all dogs with MCCC fixed all my issues, but that's too scorched earth and I don't want any mod stuff messing up this years-old save. I have no way to use the MCCC "Delete Sim" feature on the individual  dog because I can't get to the dog without a crash. I can't access the dog by using "Edit in CAS" on her owner, I CTD just after load screen, before the sim has a chance to render. I've never had the strange fox households show up in Manage Worlds, are foxes actually dogs? Still, just the fact that I can't access the dog in her family's CAS makes me pretty sure it's this one particular dog and not a fox. 

Do you know anything about how MCCC will affect my save? If I nuke all dogs and pull the mod, will it leave vestigial traces of the mod that can cause problems in the future?

Update: It is not a fox household issue, as using the filters in Manage Worlds for 'played households' and the neighborhood with the offending dog, Henford-on-Bagley, causes a CTD.

@JonaO703Trying to access the dog in any way causes a CTD.  It is definitely this dog, nuking all dogs with MCCC resolves everything, since I don't have to directly involve or load the dog.  I am reticent to introduce mods into such an old save, though, and now all my sims' dogs are gone.

@TrueMathsI'm glad you were able to figure that out.  Too bad you had to eliminate all the dogs though.  Hopefully some new ones will generate, without that game crashing glitch though.  Regarding effects from MCCC, you may want to delete the localthumbcache.package file located in the Documents / Electronic Arts / The Sims 4 folder.  This cache file can sometimes carry some effects from mods.  Happy Simming!

@TrueMaths 

I have played the game for years with MCCC.  I play a long term save that I started in 2016 so I understand what you mean about not wanting to mess up your save.  I don't think MCCC will damage your save but tbh, I don't know for absolutely sure.  All I can say for certain is that I haven't done anything with MCCC that has damaged my save yet.  It really depends on what you do and how you use the mod as it lets you do things that the game would otherwise not let you do.  Doing some things does carry a certain amount of risk.  That can be said for a lot of mods.   The only thing I can suggest for you or anyone who uses MCCC or any mod that alters gameplay is to always make a backup of your save folder before you do some things so you can revert back to it if something should go wrong along the way.

Hope this helps.