blind dogs sudden aggression

Question
I acquired a dog when I remarried that is pit bull/shepherd mix. Julius is very attached to me especially since he went blind due to a retinal disorder about 18 months ago (I call myself his seeing eye Mom). He was adopted as an adult dog from the SPCA so he's at least 10 or 11years old. He has adjusted to the blindness quite well, however, has recently shown relentless aggression towards my adult son whenever he comes over. He barks at everyone who comes to the door as he should but when my son Dan is in the house he follows the sound of his movement constantly and is visibly nervous; hair standing on back, tail etc. He has nipped him 2X in the leg leaving a mark. I don't know what to do nor how to handle his aggression. My son has been coming over to the house for about 3 years and this aggession started approximately 4-6 months ago. I've advised my son to always speak to the dog when he comes in the house. The dog never seems to get over this nervous aggression while Dan visits. Also, if Dan stays overnight and I knock on his bedroom door in the morning, Julius immediately runs down the stairs and barks.I believe Julius senses my closeness to my son and is extremely jealous but how do I handle the biting?  

Answer
Hi Marlene,

Thank you for writing to me about Julius.  I apologize for the delay.  As you may know, we had a wicked Nor'easter here and are just starting to recover from all the flooding and damage. Thank you for your patience.

When a dog suddenly has a sudden behavorial change it is imperative that a full medical exam be done by your vet, paying close attention to the thyroid and any possibly chemical imbalances in the brain.

One must also question as to whether there might have been an incident between your son and Julius that has frightened your dog.  Perhaps your son is hesitant to mention it to you for fear of upsetting you?  There may be a justifiable reason for Julius' fears, although it is never acceptable that a dog bite a human.

I would normally recommend that very serious Alpha work be done with Julius but in this case I feel that it is important to explore other avenuse such as the ones I mentioned.

After that, I would recommend bringing in a behavorist to access Julius' behavior when Dan is in the house with him.  I would be curious to know how Julius responds to your son Dan outside of the house? Have you tried taking a walk with both Julius and your son with you holding the leash and after awhile when you are all into the same walking rhythm, gently handing the leash over to Dan? If Julius and Dan can be on the same wave length and Dan shows that he is a firm and fair leader, Julius may respond in a positive way.

I wish you the best of luck.  I can tell how much you love both your dog and son and want them to get along harmoniously.

Best Regards,
Shelley Davis