Dog bedwetting (need advice please)

How old is he?
I would say a vet check is definitely in order, especially if this is a male dog as it could be prostate related.

My little dog, a female, started getting incontinent around 14 years old.

It's possible that this was related to something happening in the dog's sleep but not probable.

What you describe is called incontinence and happens when a dog urinates without realising it. The main giveaway is the absence of any pre-pottying behaviour - circling, sniffing, squatting (obviously).

Dogs are inherently clean animals and will not pee where they sleep or eat if they can possibly help it. A sign of incontinence is when a dog will pee where they are and continue to lie in it - they don't even know they've done it.

There are a variety of reasons for incontinence and it is more common in bitches than male dogs. Usually it is because of a urinary tract infection but can be due to cystitis or post-spay incontinence in bitches.

I would take him to the vet, because he could have a festering infection that may lead to all kinds of other problems such as struvite crystals if not treated. Also, your friend may not know if this is the only time it has happened, and when a UTI leads to incontinence (if that is the primary cause) then it's far gone enough to warrant a course of antibiotics.