Predefined attributes/constants in xsd enumeration

Predefined attributes/constants in xsd enumeration

I have the following xml:
<animals>
<animal name="Pongo" animalType="Dog" />
<animal name="Marie" animalType="Cat" />
<animal name="Skippy" animalType="Kangaroo" />
</animals>
I know it is possible to restrict the type of animals using an enum like
this:
<xs:simpleType name="animalType">
<xs:restriction base="xs:string">
<xs:enumeration value="Cat" />
<xs:enumeration value="Dog" />
<xs:enumeration value="Kangaroo" />
</xs:restriction>
</xs:simpleType>
What I whould like is to know automatically, based on the animalType
value, how many shoes does the animal need, after the xml parsing.
And, when a new animal type is being added, to add also the number of
walking legs for that animal.
For instance, it would be great to be possible to define something like
<xs:simpleType name="animalType">
<xs:restriction base="xs:string">
<xs:enumeration value="Cat" nbOfShoes="4" />
<xs:enumeration value="Dog" nbOfShoes="4" />
<xs:enumeration value="Kangaroo" nbOfShoes="2" />
</xs:restriction>
</xs:simpleType>
Is it possible to achieve this using xsd, or I have to implement the
numberOfShoes logic after the xml is being parsed?
Thank you.