Hi can I just clarify things first and ask some questions
Thanks for the additional information.
Because she is neutered and because the liquid has no odour (or colour?) it is almost certainly urine. This is a common problem in dogs and it’s quite common for owners to not feel it’s urine. If you needed to be sure you could take a sample to your vet who will confirm it.
The only other source that we might consider would be a vaginal discharge as with vaginitis but this is usually thick and minimal or an anal sac discharge which is also minimal and very smelly.
So this will be urinary incontinence and it's quite a common problem in middle aged female dogs. Almost always it is due to a loss of tone (strength) in the bladder sphincter muscle. This is a circular muscle that sits at the neck of the bladder and is normally active, keeping the bladder closed. Sometimes it loses tone, mainly in female dogs and this is called urethral sphincter mechanism incompetence (USMI). It occurs more commonly is spayed dogs and is thought to relate to the loss of female hormones. Up to 20% of spayed female dogs will develop this problem. In some dogs it will be intermittent, often occurring when the dog has been stressed by exercise, heat, illness or anxiety but in most cases it becomes a permanent issue and is not associated with any other problem. There is usually a good response to one or both of two types of medication. 1. Hormone therapy. Estrogen hormone supplementation can be quite effective. 2. Alpha agonists. This refers to a group of medications that stimulate the sphincter muscle directly. This is the preferable treatment and phenylpropanolamine (Proin) is the most commonly prescribed medication. Less commonly, ephedrine and pseudoephedrine are used. In order to obtain a treatment you will need to see your vet. I would advise you take a urine sample with you as occasionally urinary tract infections can cause the incontinence. Your vet will be also be able to confirm that it is urine of course.
I hope I have been of assistance. Kindest regards, Peter