Renji is getting Prozac today. While we are hoping it will help with anxiety and aggression, there is also concern that the SSRI will make things worse. We were told to expect about six weeks for improvement but I've ran into a few articles that said negative impacts could be seen far quicker. For those of you who have used Prozac (fluoxetine) on your dogs, what have you noticed? Prescription mood-altering medication is mostly uncharted territory for us; he did react very poorly to Anxitane. Rescue Remedy and Springtime's Stress Free Calmplex do help but not nearly enough.