Do guidelines for actors who do not belong to our species allow multiple individuals to be credited under one name just on account of looks?

(Pardon the lengthy subject heading of this topic.) I happened to notice that one Cujo is credited in movies filmed across a time span that vastly exceeds the average life expectancy of a Saint Bernard breed of dog (which is eight years against a 28-year-long career), so the credits seem to belong to more than one "actor". (As we know, just about all animals, if they live long enough will at least be forced into retirement due to age-related illnesses [like arthritis] or frailties, before dying.) Inasmuch, it may be proper to delete some of the credits marked as "uncredited" and to split the remaining ones by groups of years. Should we let it slide? What should be done? Mind you, it is hard to gather information about celebrities who are not human, as they might not even have birth certificates or death certificates.