Migraines and blurry vision

Does an employee have a disability as defined under the Americans with Disabilities Act when she is allergic to rabbit fur which causes her painful migraines and blurry vision? Also, was the employer required to assign her to the open position as an accommodation under the ADA? Can the employer use their policy of hiring the applicant with the best qualifications for the job as a reason to refuse to provide reassignment to an open position as a reasonable accommodation?

Cases from MA or 1st circuit or another Federal circuit court.