Our customer asked:
Our cat has been loosing weight gradually, he's 15, but the vet can't find anything wrong with him. Can you recommend a supplement? He's eating well and is perky but perhaps he cannot digest and absorb as he used to.
There are lots of reasons why an older cat can lose weight. Something must be not quite right, or he would not be losing weight. So far your vet has not been able to identify the cause, and indeed it might not be feasible to try and do so, but there will of course be a cause. This means that any attempt at treatment is just a shot in the dark and may well be missing the point completely. As long as you try things which are not going to do any harm, it is quite OK to try things.
Poor absorption of nutrients can occur because of poor digestion (breaking down of proteins etc) or it can result from poor absorption of perfectly well digested foods. The two categories are medically completely different. It is not uncommon to add some pancreatic enzyme supplement to the food for cats like this, to see if it will help. Sometime it does. For other cats, it can be purely a mal-absorption problem. These cats will sometimes respond best to a fundamental change in diet, with the new diet not containing any of the carbohydrate and proteins found in the old one. (Often this means gradually switching to a diet with no cereal in it and no chicken, lamb, etc. A fish based diet might work, or one based on venison or duck etc.) Probiotic preparations, such as Protexin Professional can also help in these circumstances.
For other cats, the weight loss is due to a metabolic problem and nothing to do with the above. That is where your vet is even more important. You could however try Pancreatic Enzyme Powder (it is quite pungent, but lots of cats actually like it), or Pro-Kolin Enterogenic, or a diet such as Ziwi Peak Venison and Fish. You can actually combine these ideas if you wish.