Thanks for the questionCustomer
In direct answer to your question : While I cannot diagnose this over the internet I can tell you that a dog which is drinking excessively is always a cause for concern and this is something you should have checked out at the next opportunity. The excessive drinking is likely to be the clue to what is going on and the panting and weight loss could well be related as well.
From my past experience I can give you a list of the conditions which might make a male dog in your one's age group drink excessively and you can see that some of these are serious conditions :
1. Diabetes mellitus
- sugar diabetes - easy diagnosis via blood test
2. Diabetes insipidus - rare but does happen - catches vets out !
3. Kidney problems - diagnosed by blood tests
4. Chronic hepatitis - diagnosed via blood tests
5. Cushings syndrome
There are many more conditions but the above are the common ones.
Here is a good link on the subject so you can look at things in depth : LINK
I am sorry I cannot offer any home remedies here as I usually like to do, the diagnosis is so wide ranging I would be concerned I might get it wrong. Accordingly all I can suggest is that you have your vet check your dog out as soon as is practicable, it would be helpful if you take a fresh urine sample with you as there are stick tests which might help your vet pin down the diagnosis. Once you know what is going on you can then start to make any decisions as to treatment etc.
If I have not answered your question fully enough or if you would like to ask more I will be on line for the next hour or so and I will be pleased to discuss your question further.
Scott Nimmo BVMS MRCVS