>>So they are only useful as immediate food or "lab rats."<<

Of course, thus means they'd need to run their experiments quickly, during the early days of a societal collapse. Not an ideal scenario.

>>You need a mammal near or above human adult weight to test for the Grunge.<<

So ideally bigger than me. (I'm toward the smaller end of adult size, but I don't count as tiny.)

>>I'm not sure if the Grunge would kill reptiles.<<

So they become guilt-free gatorskin and snakeskin leather. And fried-meat-onna-stick. And I'm sure gator teeth are good for something...bragging rights?

>>Those breeds need too much food to survive well in the Aftermath.<<

A handful of heritage breeds may be useful. To be fair, they may top out at something under a hundred pounds. (It looks like Huskies are about 75 pounds.)