Friday Abstinence: Dispensations
"In individual cases, for a just reason", a parish priest can dispense one of his parishioners from the Friday abstinence (canon 1245).
In addition, an illness requiring meat sustenance could dispense someone from the Friday abstinence, however, if non-meat food could also adequately nourish then the exemption would not hold. Similarly, if it is 'physically or morally impossible' to fulfil the law then the law does not bind (this being a standard principle of moral theology). Obviously, an overly slack application of this principle would be an abuse rather than a 'just cause'.