Is she crated? I ask because I'm wondering why she can't access water on her own during the night.

It almost sounds like she's getting her days and nights confused, so if she's physically able you might try walking her before bed time to throw her off her routine. Is she able to do any exercise?

Our elderly poodle developed dementia the last few months of his life and he had very restless nights. We had to set him up in the bathroom at night and just let him do his rambling there.

if you do crate her at night, you could get one of those bottles like they put in rabbit hutches. dogs learn to use them very quickly. if she isn't crated, can you just leave a bowl of water out for her?

What do you feed your dog at night and what time do you feed it? Have you recently changed your dogs dinner in any way.
My suggestion, check the sodium content in the food, feed earlier, walk your dog before you all go to bed, at 14 your dog should be able to hold it all night long without issue.

thanks folks, just some clarification, she isn't crated at night, she sleeps on a large dog bed in our room. She has a water bowl in the bathroom that she can get to easily but the issue is that it could have four gallons of water in it and she would empty it, ie., it's never enough. We feed her at supper hour for us, around 530 and she's been on a vet prescribed food that is sodium and fat reduced for some time, this hasn't changed in the past year. The only change is that she seems to have an unquenchable thirst at night and then the associated need to urinate but this isn't the case during the day.

well, this is VERY perplexing! if blood work and urinalysis was normal, i am baffled. even if it's a case of "old dog" dementia, that doesn't explain WHY she seems so thirsty. hmmm....

Assuming she also has access to water during the day, are you sure that she IS drinking during the day? If she's an only dog, it would be easy to measure her intake.

How long do mini schnauzers live? I know the little ones last longer, but I think I'd let her drink as much as she wants while you're figuring this out. Maybe gate her in the bathroom with some pee pads. At her age I would just be all about comfortable for her. Is she losing any weight?

I'm still suspicious of a medical issue... renal? I'd definitely get a second opinion from another vet before restricting her water.

Mini schnauzers can live to around 16 years anyway. Ours did. If she drinks amazing levels of water any time she is awake that doesn't sound right. There are some conditions where the causes for excessive thirst are endocrine and the tests in the more common panels might not show abnormalities. I'm thinking things like diabetes insipidus. I would also want a second opinion before restricting water.

thanks so much folks, your feedback is very helpful to us......it's just so odd that it's mainly at night that this thirst gets the best of her......she sleeps soundly during the day and plays as usual, bunks down at night as normal then it starts.....pacing, pacing, back and forth to the water bowl till it's empty, then growling like crazy to get some more, then she needs to go out right away and in many instances she didn't make it to the door and ends up making a puddle in the hallway.....she then comes back in, settles for a bit (and I do mean a bit as it's about 45 min at max) then it starts all over again, then by about 630 she's sleeping soundly well into that later part of the am......during the day, she will drink but no where near as much as she seems to want at night. The vet did feel the two differential diagnoses were that it was psychogenic or diabetes insipidus but she felt the latter was very unlikely......I hate the thought that she has a clear medical issue and we're not helping her and we also know that being up all night every night isn't good for any of us........I've started to put a diaper on her as a safe guard and more than once it's soaked when i check it! think i should go back to the same vet with her and just say it's not feeling "right" that it's completely in her head?

diabetes insipidus........you don't hear about it everyday......and I'm wondering if that's why she'd think it unlikely? It can be temporary or permanent and it can come on as sequelae to other underlying issues like injuries or cancers. There are some relatively straight-foward tests around to confirm or rule out that diagnosis.

If a simple test can make that differentiation, I'm wondering why it isn't done.

Agree with Calliope, if the vets have ruled out the common, they need to test for the less common before labeling this as behavioral. Since standard blood and urine tests would not show D.Insipidus, talk with your vet about the testing for that. If not supportive, go get that second opinion.

A little story for you. I have NGA greyhounds, and volunteer a bit for the breed. I drove down on a Saturday afternoon this spring to pick up an 11 yo dying dog whose adopters were no longer able to care for him. He was peeing in the house constantly, and had lost 20% of his weight, could barely support himself to stand. I lifted him into the car and honestly didn't think he'd be alive when I got back to my house with him. When we got home, he wanted only to drink and pee drink and pee. If I had filled the bathtub with water, he would have drank it all.

At midnight, I put comforters in a crate and lined the front with as many bowls of water as would fit and went to bed. That comforter was saturated and heavy the next morning. I had to put it through the spin cycle before I could wash it. Took him to the vet that morning, and the urine said D.Mellitus but vet and I both said - "nah greyhounds don't get DM." Blood test confirmed DM. DM and DI are different, but it could be your vet simply thinks DI is not common in Schnauzers so not testing for it. Greyhounds rarely ever get Diabetes Mellitus, but I've got a greyhound with DM :) Maybe you've got a Schnauzer with DI. Test for it.

The death's door greyhound is regulated now, he's put his weight back on and some of his muscle. He is happy and trots a bit when my girl greys run. 11 is fairly old for a grey, but he's got more time because he has good vets and he's on insulin. The med for DI is desmopressin. Worth doing a bit more testing for your girl?

My own vet doesn't have a lot of testing equipment and sends samples off they can't do on-site. Many larger vet practises have their own equipment (quite expensive and your fees probably reflect paying for them) and might be reluctant to send samples off-site. They may also be trying to save you money because some testing can be pretty expensive. However, the definitive tests could actually be cheaper than repeated vet visits with limited results.

I'm certainly not qualified to suggest or diagnose any animal disease. My background has been in human health care, but I remember I didn't even know this condition existed until I studied it in a nursing class. Then found our family facing the possibility of it in a relative who had pituitary issues. It's not as rare as one might assume, especially if it's a secondary condition to other health issues like head injuries or neoplasms or even changes in the kidney from aging.

thanks folks, the vet mentioned that the DI test would involve leaving her there for the day and they would not give her anything to drink then at various intervals analyze her urine to see how it was concentrating to determine if in fact it is diabetes insipidus.....will call tomorrow am to get her in,