Could be his sight then, just like geriatric patients, dogs can always get more restless and aggravated when they can't physically do something that would've been normal for them. I would seriously try antidepressants first for his aggressiveness before having to escalate in anything like the talk.
Also, forgot to add on my original comment, you heard about pill pockets? They worked a charm for one of my other dogs that is ironically morbidly obese but is picky about what is in her dog food to the point where she would throw it up if she felt anything off about it. https://www.amazon.com/Greenies-Pockets-Capsule-Treats-Hickory/dp/B01EJDFTGS/ref=sr_1_6?crid=2IXCTGY32K4YK&dchild=1&keywords=pill+pockets+for+dogs&qid=1609637197&sprefix=pill+pocket%2Caps%2C173&sr=8-6
Deal link: Amazon
NOTE: Are you looking for discounts on a specific product? Search for the product in our official Discord Server! We are gearing up for Black Friday and Cyber Monday! Grab the deals before anyone else! Join our Discord Server to get real-time notifications on all deals. We have category-wise Discord channels. Disclaimer: Some deal links on this sub may be affiliated