That looks fine to me, except I think that sitemap line should read:
Code:
Sitemap: http://paralyzed-dogs.askavetquestion.com/sitemap.xml.gz
Make sure the robots.txt file is in the root directory on your server, or if it's a subdomain as in your case, in the root directory of the subdomain.
Also doubt check that you used a plain text editor for editing or creating that file and that it is saved in plain text or ASCII format, not unicode or anything.