overwieght pit bull

Question
i have a five year old red she is handicapped (amputated back right paw) and has severe allergies which require a daily dose of pregnazone she is 65 pounds and so over weight that she has arthritis and with the steroids she is on she will continue to gain weight (says the vet) i have cut her food in half and because of her disability she cannot exercise for more than about 10 minutes. i am worried that this is cutting her life span dramatically. can you please help.

Answer
All I can suggest is less food.  This may be a case for a light dog food.  Cutting back on a regular food too far can leave the dog short of vitamins, minerals, and protein.  

Zepher, a 4 year old Lab that returned to our daughters care weighing 92 pounds.  She has him down near the 67 pounds he was as lean one year old just feeding him less of his Pro Plan.  Your dogs sounds different.