There is r/petloss for that. I lost my dog Nike (image link) in 2019, and it devastated me. About a week later, I posted her with this image (ext link: imgur) to petloss.

I don't think these folks are disgusting for venting about their lost loved ones. It is hard losing a pet. I guess at that time, I wanted someone else in the world to know about her, the life she lived with us, how dearly we loved her, and how much she's missed. It was a pretty long-winded eulogy. Conciseness was never my strong suit. Different people grieve differently.

But I do believe that you should look for the relevant subs/communities to post about losing a pet and refrain from making that kind of post on those for more general pet posting. At the same time, I think awareness is key. I'd reckon if you're posting to r/cats or r/dogs instead of r/petloss, you're probably not aware of it. I tend to assume grieving pet parents aren't trying to karma farm.

The world is already shitty enough, and I don't need to bring myself down with that kind of thinking anyway.