Overweight Shihtzu

I just adopted a 5 yr old Shih Tzu named Roxy from a rescue shelter a few days ago. She has been without a home for almost 4 years. She is so amazingly cute and loving.. Only thing is that she is 25 lbs. The owner of the shelter mentioned that she should probably be closer to 15 to 18 lbs. I am trying to wean her off the wet food that they have been giving her at the shelter. But she is constantly running back to her food bowl to see if there's more. Does anyone have any ideas as to how much dry food is enough to meet her daily requirements? And also she can't get enough to drink. She is constantly going out to pee. I can't get in to see my vet for a few weeks.
   
Thanks..

She should be eating 1/2 ounce (28.4 grams) of food per pound that she weighs.
   
However, she is overweight so obviously if you use her true weight you are making her fatter.
   
Start at 12 ounces per day and then try to cut back little by little.
   
She could just be drinking a lot because she is used to eating like a pig and now she has to do something to fill herself because you aren't letting her gorge herself.
   
If there is no food in her bowl but there is water, that is her only choice so she is taking it.
   
It probably isn't all bad for a fat dog to drink a lot of water since, as with humans who are dieting, it will help 'flush out' her system and will make her feel full without adding a single calorie.
   
However, overdrinking can lead to problems and can also be a sign of diabetes so be sure to bring this to the vet's attention.
   
Also if she is permitted to drink late into the evening she may eventually start to pee herself in the night so be sure to cut off the water early in the evening and give her a good last potty break (making sure she actually pees).
   
Try to exercise her as much as possible to burn off the fat, of course, and no treats or snacks for an overweight dog is just common sense.
   
If you really want to treat her try carrots. We had a dog who would absolutely do a backflip for a carrot and of course that is not fattening.
   
Apples (carefully cored and seeded or else they are a choking risk) and sweet potatoes (cooked and served either mashed or cut up) are also low-cal snacks you can try.
   
No raisins, grapes or avocado (all toxic).
   
If you decide to try fruits and veggies, try them in blocks, i.e. start with carrots and use just carrots for a week.
   
This way if the dog has an allergy or the chosen food gives her the runs you will know which food is causing the problem.
   
Good luck!
   

Thanks so much for your quick reply.. That helps so much.. I will try that.
   
I never would have thought about carrots or apples as a treat.. as I am trying to train her as well to sit and stay, so I will definitely try those rather than doggie treats.
   
Thanks..