You must be referring to an offline casino because an online casino will never allowed that to happen since they don't know who is using their sites and can run away when they lose. An online casino can never allow such practice or they'll be losing money in the business.
I haven't heard of an offline casino offering loan bets either, it looks possible but I haven't heard of any one and if there's one operating, we have to avoid them because we'll put ourselves in unpayable debts. Gambling is very addictive and having free money is dangerous.
You should never borrow money to gamble and you should never take loans as well. Gambling should be done with spare money because there's a high possiblity that you'll lose and it's better to lose your spare money than lose money that you still have to payback.