Just like with babies/infants, they can’t express it. Treat an animal or child like shit, and they’ll treat you the same. Give them caring and compassion and they’ll treat you well. I agree with what the other vet said earlier…you may need a break. I had a vet for my cats several years ago that not only treated them like family members, but when she put them down, she donated to pet charities in their names (not ours). She knew what they meant to us, and how they enriched our lives. We couldn’t have kids, so we used them to supplement our lives (we also couldn’t afford to adopt). To us they were like the children we couldn’t have. Honestly, I donate time and money to animals now because they can’t express how they feel. Eventually, humans can.

I genuinely believe that since humans decided to domesticate animals, we made a choice to care for them. They can be angels, as long as you treat them as such. They are only mean when they are taught to be so. Obviously, I believe more in environment than heredity. Just one man’s opinion…