My smartest rat easily had high dog-level intelligence, and after being trained to not chew electrical cords or furniture, and not to hoard food, was given full run-of-the-house privileges. She had a regular routine of ‘tucking me in’ at night, snuggling up to me from the time I turned off the lights until I fell asleep. When I caught a cold or flu, she’d continually check on me and spend lots of time grooming me.

All the rats shared a large cage on a table. Since only one rat had passed all my requirements for freedom, I trained her to be able to go to and from the cage at will, while training all the others to fear leaving the table on which the cage sat (mild aversion training, nothing traumatic).

The Sprague-Dawley lab rats (I forget the strain code) were only capable of minimal training, and also were minimally interactive or affectionate with me, though they were never hostile, and the other rats clearly loved them. The lab rats were also the shortest-lived, succumbing to respiratory infections at about 1 year of age.

The other rats lived longer, were better able to beat the respiratory infections, and lived long enough to get multiple mammary tumors (which are common in female rats) and survive surgery.

While all my rats did their best training while young, all but the lab rats continued to learn throughout their lives, though at diminishing rates. In particular, they became more social with me as time progressed. It was especially joyful for me when I came home from work to see them lined up on the edge of the table eager to greet me!

What was most amazing to me was their behavior when near death. When they became too weak for surgery and/or drugs failed to work, I would euthanize only those who were in obvious pain. While I could detect some of the pain on my own, such as while handling them, the clearest indication was the behavior of the other rats. A rat that was infirm but was in no pain would receive occasional grooming and food from the other rats. A rat in pain would be surrounded by the other rats, snuggled together.

I loved having rats as pets, but the frequent tiny deaths took their toll on me, and after the first 5 deaths I decided I would not replenish their population. When my last rat started to fail, I took time off work to be with her, holding her continually. I’m absolutely certain she sensed my melancholy mood, for she kept trying to groom me right up to the end, despite being tumor-ridden and blind herself.

The notion of rat empathy(and intelligence) is no secret to those of us who have shared our lives with them.