No, Au Pairs cannot have pet care responsibilities. Au Pairs can only provide child care related services and cannot be required to care for a pet.
Au Pairs can however, assist with pet care when it pertains to child care. For example, your Au Pair can assist your children who have pet care responsibilities. Some Au Pairs become so embedded into your family’s life that they voluntarily care for your pet(s) in addition to your children. Au Pairs can willingly assist with pet care, but it cannot be a formal responsibility or duty.
Au Pair applications contain information about pet restrictions the candidate may (or may not) have.