I have a six year old German Shepard, who has been acting strangly lately, such as walking backwards across a tile floor, crying when putting him to bed, acting scared and avoiding family members. A few days ago I heard a commercial that said mental disorders could be a side affect of flea preventatives. He does not take any, but has been on Interceptor Flavor Tabs for heartworm prevention. Could his new behavior be a side affect, or do you have any other thoughts?
I do not think this is a result of any of the medication you mentioned. I recommend a visit to the vet for a blood test. Good luck, vetcare