It is classic for diabetes, so it's worth a check with the vet.
Well, I had a similar thing going on with my dog, but it appears to have resolved itself right now.
If you have hot weather, and your dog has also been exercising hard, then you can expect she will drink more. Also if she has been fed anything which is salty.....
BUT...suddenly drinking a lot more can be a sign of many things. Has she been spayed? If not, it can be a sign of the dreaded Pyometra. Unusual, but not impossible in a 4 year old.
Or it can be a sign of (please don't let me scare you here. I am just reeling off all the possibles!) -Sugar Diabetes, Diabetes Insipidus ("Water Diabetes"), Hypercalcemia, Cushing's....to name but a few possible problems. If it is Diabetes Insipidus, this can be managed quite well, and even moreso if the dog is an outdoor type.
Take her in to be checked over. Take a fresh urine sample with you. An early morning urine sample is best, as the urine will also be checked for "specific gravity", and that can increase and decrease throughout the day depending on fluid intake. The early morning urine sample will give the specific gravity at its stable level.
If the urine sample shows all is normal, the vet may suggest waiting a few weeks to see if the drinking/urinating steadies out -as it can sometimes. And if not, may recommend a blood sample be taken to get a better view of what is going on with her organs. Or the vet may suggest a blood sample be taken straight away.
Usually the urine will show if there are any imbalances happening, as many things show up in thew urine, but for more detailed diagnosis, a blood sample will be better.
With my dog, she had been playing in the sea, catching the frisbee time and time again, and started drinking more water after that. This went on for a few weeks! The vet said she could have been flushing the salt out of her system. It did appear to be that way as she is not drinking as much now.
The average dog drinks 3 to 4 cups of water per 20 pounds of body weight per day. So as a simple example, a 60 pound dog would drink between 9 and 12 cups a day. If your dog is drinking way more than he should be and you find yourself filling his water bowl several times a day, a visit to the vet is DEFINITELY in order since polydipsia (increased thirst) is a symptom of several very serious diseases.
Increased water consumption is usually the first symptom noticed in diabetic dogs. Kidney disease, liver disease or pyometra, a potentially fatal infection of the uterus in unspayed females also cause increased thirst. If it's diabetes that is causing the increased thirst, depending on how long your dog has had it, you may also see her exhibiting a HUGE appetite but in spite of how much she may eat, she will continually lose weight. The appetite can get so out of control that a dog that is normally not given to tearing into trash bags or raiding peoples' plates will start doing just that, and other things that are grossly out of character for her in order to get food, ANY food.
I would definitely make an appointment with the vet ASAP to have bloodwork done. While the word diabetes strikes fear in our hearts, it is no longer as scary as it used to be. It can be managed quite easily with diet and medication and your dog can have a normal lifespan and lead a normal life. If it's kidney disease or liver disease, your vet would have to advise you on which course he or she felt would be in the best interest of your dog. In any case, it would be best to make an appointment first thing tomorrow morning! And PLEASE keep us posted as to the outcome of your visit!
Cushing disease also leads to the dog being thirsty and urinating all the time not to mention the ravenous hunger all the time. My dog has this disease and I feel so helpless seeing the downward trent in his health. I had him tested for diabetis, but was told it was Cushings. If there is anyone out there who had a dog with Cushings and is using the alternative medicine to treat it, please let me know how it works. I would definitely like try it on Boxy.