Tl;dr
He is and old mature male. Today I noticed this white gunk on the butt, picture related. I wonder could this just be a dirty butt that will go away, or would it be something worse that is painful and I should take some type of action? I'll add a picture and explanation of my T's history.
Longer story:
Actually my first post here about my first tarantula, after lurking for years heh.
This is my first tarantula that I adopted from its previous owner. They did not know its species or gender, but it was quite curly and had a burrow so I assumed it was a burrowing species. A year after this it started with a bunch of mating behaviour, so I realised it was a mature male and accepted in my heart it might die in a couple of weeks to a year. Well 1,5 years later this old guy is still kicking. He has though lost half of his hair, gotten whiter and scrawnier. Sometimes not eating for months and I think he will die, but then he comes back around, e.g. this week and starts eating again, keeping me on my toes lol.
Today I noticed white gunk on his butt, and I wondered is it just some poop that will wash away or is it something worse that gives him pain. He has been moving around normally, ate yesterday, drank some water today for example. He has not started pacing around or hidden away which I would think are signs of pain.
I looked through some posts on this forum about white butts and there were so many different answers, mostly saying it is something bad. I guess my main thought is, if it turns out to be something bad that would give my T lots of pain and is hard to cure, because he's so old I would probably euthanise him then, cause I don't want him to suffer.

He is and old mature male. Today I noticed this white gunk on the butt, picture related. I wonder could this just be a dirty butt that will go away, or would it be something worse that is painful and I should take some type of action? I'll add a picture and explanation of my T's history.
Longer story:
Actually my first post here about my first tarantula, after lurking for years heh.
This is my first tarantula that I adopted from its previous owner. They did not know its species or gender, but it was quite curly and had a burrow so I assumed it was a burrowing species. A year after this it started with a bunch of mating behaviour, so I realised it was a mature male and accepted in my heart it might die in a couple of weeks to a year. Well 1,5 years later this old guy is still kicking. He has though lost half of his hair, gotten whiter and scrawnier. Sometimes not eating for months and I think he will die, but then he comes back around, e.g. this week and starts eating again, keeping me on my toes lol.
Today I noticed white gunk on his butt, and I wondered is it just some poop that will wash away or is it something worse that gives him pain. He has been moving around normally, ate yesterday, drank some water today for example. He has not started pacing around or hidden away which I would think are signs of pain.
I looked through some posts on this forum about white butts and there were so many different answers, mostly saying it is something bad. I guess my main thought is, if it turns out to be something bad that would give my T lots of pain and is hard to cure, because he's so old I would probably euthanise him then, cause I don't want him to suffer.

