Being rejected for jobs after interview, discrimination?

I live I Australia, Queensland to be specific, and I have interviewed for 4 jobs past couple of months. Of course I take my Assistance Dog (service dog) with me. She is fully certified with Guide Hearing and Assistance Dogs Queensland, undergone training and 3 yearly public access tests. They never ask anything about my dog however I always get rejected with near to the same reasons along the lines of "The decision was based on a careful evaluation of your qualifications and experience, as well as a comparison with other candidates. While you have many strengths, we felt that another candidate was a better fit for our current needs and goals."

One of the jobs I applied for I held the same position when I was a student as a casual 3 years ago and only left as it a short-term parental leave contract.

I feel as if I'm being discriminated against as i I have an Assistance Dog. How do I prove this? I've been struggling getting a job.