Hi, I'm Dr. Gregg and I will try to answer your questions today. Is she actively squatting and urinating in your bed or does it seem she is unaware of it, with urine just leaking out of her? Has she been spayed?
Thank you for that answer. In that case I would suspect your dog (name?) has a urinary tract infection, causing her discomfort and urgency to urinate. It is very unusual for a dog to urinate where they rest. Urinary Tract Infections (UTI's) are not uncommon in young dogs. Sometimes, young dogs coming into heat can have an increased urinary urgency as well. What I would suggest is to get a urine sample, or your dog, to your Vet for them to check for infection. If you want to try to collect the urine sample yourself you can try to collect urine with a clean ladle and transport, in a clean glass jar, to your Vet. It is best to refrigerate the urine if it is going to be more than an hour before you can get the sample to your Vet.
It is also possible that your dog could have a bladder stone causing the problem, but she is pretty young for that problem
Most UTI's can be treated with a course of oral antibiotics
If you are sure which one of the two dogs is urinating in your bed, you should not need to check the other. UTI's are not contagious. If the cause is a pending heat cycle, then it should help. Otherwise it should not make a difference. I would recommend to spay your girls to reduce the risk of breast cancer, later in life.
I suspect the urgency to urinate causes her to pee where she is rather than go outside
That's a little curious, but it may be that she gets most comfortable there, perhaps sleeping more deeply and is overcome by the urge to urinate, by "surprise". When an irritated bladder wants to empty, the urge can come quite quickly
I don't think that is the case. She must be pretty uncomfortable to "soil her nest" Hopefully this will resolve with a course of antibiotics. I wish you luck with your two girls. If I can be of further assistance, feel free to ask. If not please accept my answers. Best wishes. Dr. Gregg