frequent urination and thirst

Question
I have a 9 year old great dane. I have had him since he was a puppy. He has started urinating about every hour or two, and drinking ALOT. He is squating to urinate. When he goes out he urinates a steady stream and pees forever. He will do this 2 to 3 times each time he is let out. I had blood work done and it is not: diabetes, Addisons disease, or renal failure.
He had blood and crystals in his urine. He has been on Keflex (1000 mg in am and another 1000 mg in PM) since Monday. He isn't getting any better at all. Should I be seeing some improvement by now?
Do you think it could be food related. He has been on Alpo Large Breed all of his life. The vet said it was O.K., but not sure. I love this dog so much and am very concerned.

Answer
Jay,

It is good to know that you have already had him to the vet. Did they do any testing for thyroid?

Polydipsia refers to an increased level of thirst in dogs, while polyuria refers to an abnormally high urine production.

The primary causes of polydipsia and polyuria include congenital abnormalities, and those associated with renal failure. Congenital diseases can include diabetes, a decrease in steroid production by the adrenal glands, and some rare psychological disorders. Kidney diseases, meanwhile, can be congenitally based, or can be linked to tumors, increased steroid production, increased thyroid hormone levels, and electrolyte or hormonal disorders.

Other potential factors behind polydipsia and polyuria are low protein diets, medications that are prescribed for removing excess fluid from the body (diuretics), and age. The younger and more active a dog is, the more likely it is that it will have intermittent increases in thirst and urination.

Taken from PetMD.

As you can see your veterinarian has already ruled out renal failure, diabetes and Addision's disease. There are a few more things you can rule out as listed above, steroid production, kidney disease, increased thyroid levels and hormonal disorders.

It could also be linked to his food, Alpo is not in any way, shape or form a balanced diet for any dog let alone a Great Dane. Below are the ingredients of your dog food:

Ground yellow corn, meat and bone meal, soybean meal, beef tallow preserved with mixed-tocopherols (form of Vitamin E), corn gluten meal, animal digest, salt, L-Lysine monohydrochloride, potassium chloride, zinc sulfate, Vitamin E supplement, added color (Red 40, Yellow 5, Blue 2, Yellow 6), choline chloride, ferrous sulfate, manganese sulfate, niacin, Vitamin A supplement, calcium carbonate, copper sulfate, calcium pantothenate, natural flavor, pyridoxine hydrochloride, Vitamin B-12 supplement, thiamine mononitrate, Vitamin D-3 supplement, riboflavin supplement, calcium iodate, menadione sodium bisulfite complex (source of Vitamin K activity), folic acid, biotin, sodium selenite. E-5020.

Ground Yellow Corn-A filler
Meat and bone meal-no specific meat a bone meal?
soybean meal-another filler
beef tallow preserved with mixed tocopherols-anything with preserves especially in the first 5 ingredients should be burned.
Corn gluten meal-oh goodness, CORN, Again...

If you want a good, and relatively inexpensive alternative you can try Walmart and get Pure Balance in either Chicken and Rice or Lamb and Rice, it is comparable to Blue Buffalo which is a 5 start rated dog food, but for half the price.

Other foods that I personally recommend is:
Blue Buffalo
Simply Nourish
Orijen
Taste of the Wild
Solid Gold
Fromm
Nature's Variety

Sorry for my late response but I do hope he is doing well on the medication, sometimes it can take up to 72 hours for it to start working. Like the portion says above, sometimes frequent urination is nothing more then the dog getting old, and it is something you will have to adjust your schedule to so that you do not have accidents in the house.