I grew up in a rural area in the woods on a pseudo farm. This situation usually equals to having many pets growing up, and this was definitely the case for me. We almost always had multiple dogs and cats at any given point. Sadly, this also means I have a lot of stories of pets dying. I'll just pick a few here.
One time we were boarding and breeding beagles for a friend of my parents'. They had a huge fenced area that was half wooded, half open field, nice big dog houses... We had one male and two females in the beginning. A few years after we had them, I came home from school one day and found out Jack, the boy, had died. My parents told me he had heartworm and died. Even though I was young, I had already had 2 pets die of heartworms, so I was sad but understood.
I found out about 2 years ago that Jack actually died because he went into cardiac arrest... Because he wouldn't stop trying to fuck everything in sight.
I had two blue tick hounds once - they were brothers named Blue and Beau. We didn't really have neighbors, but the closest person to us was across the field from my house about a mile away. He was a preacher, who's daughter lived in the other side of the field. Our dogs usually ran free, my parents didn't have an inside pet till right before I went to college. I loved those dogs. They were smart, sweet, and followed me and protected me on all my woodland adventures. One day, apparently the preacher got tired of them wandering through his yard on their treks through the property. He poisoned a piece of chicken with antifreeze and Beau ate it and died. Blue either didn't eat any, or not as much and was fine. For a time. In the following weeks, Blue never left Beau's graveside. He stopped eating, stopped drinking, and wouldn't come when called. We tried feeding him all kinds of stuff and he refused. At one point he wandered off and we couldn't find him. I'd hoped he ran away and was happy somewhere else, but a few days later, I found him dead on his brother's grave.
I had a basset hound that got run over. My parents found her. At this stage in my life, I was dealing with the idea of death in... A not so healthy way. When I came home from school and found out she had died, I got upset that I didn't get to see her and say goodbye, so I went outside and tried to dig her up. But nothing was in the grave. I don't remember how my parents smoothed it over then, but yet again a few years ago the story came up. The dog was in too bad a shape to even... "collect" to bury, so my parents had faked a little grave for me to go to.
I finally had a dog die of old age 5 years ago. Her name was Fearless. She was the dog I grew up with. She went into her dog house and died in her sleep. She was my best friend, my companion, my protector, my therapist, my playmate. When she died, she took a large part of me with her.
Every pet I've ever owned has a piece of me with them. They were all my very best friends. I cried with them, laughed with them, hugged them, felt bad for yelling at them, talked to them, and felt like I knew them like I know any person or place. I made a place for each of them in my heart, and each of them gave me their whole entire hearts to live in.