Impairment and non-human organisms

Consider a horse with three legs, a bird with one wing, an oak tree without bark, and a yeast cell unable to reproduce. There is something that all four have in common with each other, and which they also have in common with the human who has only one leg. And it seems to me to be important for an account of disability to acknowledge that which all these five organisms have in common. If the right account of disability is completely disjoined from anything that happens in non-human organisms—or even from anything that happens in non-social organisms—then there is another concept in the neighborhood that we really should also be studying in addition to disability, maybe “impairment”.

Moreover, it seems clear the thing that the five organisms in my examples have in common is bad as far as it goes, though of course it might be good for the organism on balance (the one-winged bird might be taken into a zoo, and thereby saved from a predator).