losing weight

M'Guy has lost weight in the past month. He has had a small tumor in his mouth for a long time and I was thinking perhaps that was the problem so I've switched him to soft food but he isn't interested enough to regain any weight. How can I get some weight back on him? What foods are richest, most fattening? Suggestions?

[Dean Vicksman, D.V.M.]

Thanks for coming to medhelp.org for help.  Having a 16 year old kitty that has sudden weight loss can be very concerning. It is possible that the tumor is the source of the weight loss but I am concerned that there is something more serious going on.   Several important questions need to be answered.  First is he losing weight in the face of a normal to increased appetite, or is he not eating well and losing weight?  There are many causes of weight loss in older cats.
For example there is Diabetes, Hyperthyroidism, (overactive thyroid), and Kidney Disease, just to name a few.  I would first recommend a physical exam from your veterinarian.  Based on that physical exam, hopefully your veterinarian can get an idea as to weather that tumor is a problem or not. If they feel that the problem is more then the tumor they will probably recommend more diagnostic tests like a blood tests and a urinalysis.  This will help them a good start to evaluate if there is an underlying problem besides the tumor.
Hope this helps,
Please keep me posted.
Dr Vicksman