I have a 10 year old Tom who is on a diet of renal sensitive food due to on-going kidney stones. Unfortunately he has now developed a sensitivity to this food and it gives him very bad diarrhea. He has lost a third of his body weight in three months. He has had blood tests, feacal matter tests and x-rays which have all come back negative. Our vet has tried anibiotics, worming and steroids but none has worked. The only option that has worked is to put him on convalesence food but he cannot stay on this because of his kidney stones. Changing the brand of food did not make a difference.

Any suggestions?

If the food is definitely the problem then there are several manufacturers of diets suitable for stones so you could try others. Do not necessarily assume the problem is the food and so I would do the following:

1. Check the cat does not have an overactive thyroid.
2: Treat for Giardia (panacur for 5 days or metronidazole for 3+ weeks) as this can be difficult to identify in faecal tests.
3. if unsuccessful test for B12/folate and fTLI to rule out gut/pancreas problems.
4. Ultrasound of the gut may be useful if these tests are normal as well as tests for FIV and FIP.