Hello, my name is***** and I have over 20 years of experience as a veterinarian.
I am sorry to hear that Jake is drinking and urinating a significant amount more then usual, and is unable to hold his urine.
Is he eating less then usual?
A normal dog needs to take in 1 to 2 ounces of fluid per pound of body weight in a 24 hour period. That includes what he drinks as well as water found in his food. Dogs that eat canned food therefore need to drink less. Of course in hot weather they drink more.
So for example a 75 pound dog will usually drink 75 to 150 ounces in a 24 hour day (roughly 2-4 quarts of water). They drink more when eating all dry food and less with all canned because canned food is primarily water.
I would measure the amount of water he drinks in a 24 hour period for a couple days to see if he truly is drinking too much. Put out a measured amount and then keep track of any added and subtract what is left at the end of a 24 hour period.
If he is eating dry food and it is warm where you are and he is drinking more then 2 ounces per pound of body weight over a 24 hour period or if he is drinking more then 1 ounce per pound of body weight and he is eating canned food and the weather has been cool then he is drinking more than he should need.
It is a good idea to have a measurement of how much he is truly drinking to know how concerned we need to be. Depending upon his weight theoretically he may not be drinking an excessive amount for his size, but since there has been a change in the amount he is drinking and he is having trouble holding his urine I am concerned.
I would be concerned about internal organ disease (especially kidney disease, but liver disease is possible too especially because he is a Doberman and they are prone to liver disease) or an infection, especially in his urinary tract (if he is not neutered a prostatic infection would be a concern) as well as ketoacidotic diabetes or some types of cancer that cause increased water consumption and thus increased urination.
If his appetite is off his loss of appetite can be due to increased organ waste causing gastrointestinal irritation or by products of an infection suppressing his appetite or a mass taking up abdominal space and putting pressure on his stomach and intestines such that he doesn't want to eat.
I highly recommend that Jake see his veterinarian for an examination, complete blood count and biochemistry profile as well as a urinalysis and maybe abdominal radiographs or an ultrasound to diagnose his condition.
If he has pale gums and tongue or a bloated looking abdomen I recommend that he been seen as soon as possible as that could indicate internal bleeding or a large abdominal mass.
In the meantime do not restrict his water, as tempting as that may be to do, let him have as much as he wants. Just get him out to urinate as often as possible. If we restrict water in dogs with underlying internal organ disease or an infection we risk permanent organ damage.
Please let me know if you have any further questions.