Does owning horses/age influence the chance of getting a loan?

... €12,000 loan, ...

Sorry, I misread that ;)
Regarding living expenses:
I earn 2000, have no hobbies and total living expenses of 800, so I can spend 1200 per month on financing.
If I take up a hobby that costs me another 500 per month, I can only spend 700. Makes sense, right? :)

ypg, yes of course that is logical. That's not what I meant ;) Rather whether the banks say: a horse is flat-rated at €500 (no matter how much it really costs), such a flat rate like with living expenses, regardless of whether you actually need the amount in full or not. That's more what I meant.

A horse is your private matter and therefore a hobby. Banks are not interested in your hobby. You have to convey your living expenses to them so they can see how much is left at the end for financing. There are also flat rates for this (e.g., food, hygiene, and insurance). For extras—no matter what, whether a horse, a leased Bugatti, or expensive trips... whatever you don’t want to do without—you just have to invest more of your own money.

Regarding flat rates: it is not always advantageous to rely on flat rates. Hobbies like sports activities are countered by club fees of 15 euros per month versus 50 euros for a fitness trainer. For things like horse ownership, there is no flat rate. It's just an individual hobby :)

ypg: thanks, the information really helps me! :)