How long does it take for lethal mutie cubs to die?

I got a conjoined twins cub and just wanna know how much time I have to buy gold cones before he dies. Is there a guaranteed time frame like 1-3 rollovers or can he die at a random rollover like any other puppy with low survival chance?

Also sorry if I posted this in the wrong place, this is the first time I've made a post like this

I don't think anybody knows, unfortunately. Nobody's let their lethals die yet.

On Lioden, it's a guaranteed thing after a specific number of rollovers depending on the mutation, and since they don't have art for higher stages than Puppy, I assume it's similar here (although it might be in addition to regular mortality calculations).

If it's like Lioden, you'll have a bit of time with this one. The artwork looks like an older pup than the other lethals, so I assume they naturally survive into the Young Pup/regular pup stage.

They can die sooner then they would otherwise if they aren't protected, I am pretty sure. So better make sure your baby is well protected.