Expert: Jessica - 12/3/2009

Question
My cat is about 11 years old, I adopted him when he was about 2 years old and he has always been a BIG boy, since I moved in August he has lost weight...should I worry or is it all probably just him being emotional...even though I have moved with him many times before...it seems different this time..I don't know if I am worried for no reason or if this worry is legitimate and I need to take him to the vet...  

Answer
Hi Kelly.  I think you have reason to worry, and he should see the vet.  One of the most common reasons overweight senior kitties begin to lose weight is diabetes.  Diabetes is very common in cats, and your kitty has three strikes against him - it's more common in males, it's much more common in cats 10 years of age and older, and extra pounds are quite often the trigger of diabetes.

The first sign of diabetes in cats usually is weight loss.  But owners may notice the cat is eating more than usual.  This is because his body is unable to utilize the sugars that are in his food efficiently, so he eats more in an effort to nourish himself, but he continues to lose weight.  Additionally, the owner will eventually notice the kitty is drinking a lot of water and is also urinating in large amounts.  When the diabetes becomes advanced, the cat may have nerve damage in his hind legs, called diabetic neuropathy, which causes him to walk on his hocks (the last joint of his leg).  He may become exhausted after walking just a few steps and will be reluctant to climb or jump to places where he used to feel comfortable.

Sometimes a change in diet will help control diabetes, but most diabetic cats require insulin.  None of my diabetics even know they're getting a shot.  However you decide to proceed, through insulin or prescription diet or both, it's important to get blood sugar under control quickly to prevent damage to the kidneys, liver, pancreas and eyes (due to high blood pressure).

However, there are other possible causes of dramatic weight loss in older kitties, including overactive thyroid, which is also quite common, and kidney failure.  Hyperthyroidism can be controlled with a twice daily pill, or if he's bad at taking pills, the pharmacy can compound the medication into a cream that gets rubbed into the skin at the tip of the ear.  Kidney failure is more difficult to manage and would consist of a special diet, fluids under the skin at home and various medications.

There are less common causes of weight loss such as liver disease, pancreatitis, cancer, long-standing infection and even depression is possible.  Whatever the cause, I hope it's treatable and that he's back to himself soon!

Jessica