Welcome to Just Answer! I would like to help you and your cat with this question, but need a bit more information in order to better assist you.
Unfortunately, FIP is hard to diagnose as test results are unreliable; by the time symptoms are identified as likely resulting from FIP, the disease has already significantly progressed.
The only way to care for an FIP-positive cat is to provide supportive care based upon the symptoms. A vaccine does exist for this virus but is quite controversial and is not frequently used. The best prevention is to minimize a cat's possibilities of exposure.
So, then we come to treating diarrhea. The things that I would try are:
1. Metronidazole -
this antibiotic kills the "bad" bacteria in the intestines and spares the good.
Here is more about metronidazole: http://www.petplace.com/drug-library/metronidazole-flagyl/page1.aspx
This would be what was in the yogurt you tried. Often, diarrhea in cats is due to an overgrowth of "bad" (anaerobic) bacteria in the intestines. If you give your cat a probiotic, it will help to re-establish "good" bacteria in her intestines. You can either get FortiFlora from your veterinarian, or you could use Culturelle (1/2 - 1 capsule per day for a cat, sprinkled on her food). You need to continue treatment for 1 month in order to have this be effective. Here is more about them: http://www.culturelle.com/ http://www.healthypets.com/fortiflora30.html
3. Diet changes Diarrhea can be due to fibre in the food, so in some cats the problem is resolved by trying a low-residue food (low fibre). Purina makes a low-residue cat food you can get at your vet clinic. Here is a link to it: http://shopping.msn.com/specs/cat-food-purina-veterinary-diets-en-gastroenteric-feline-formula-dry-cat-food/itemid933787345/?itemtext=itemname:cat-food-purina-veterinary-diets-en-gastroenteric-feline-formula-dry-cat-food
Other cats seem to have diarrhea due to food allergies. These cats' feces are normal if the cat eat a hypoallergenic diet. Again, these would be available from your vet. You would need to commit to a 90 day trial where this was the ONLY thing your cat was allowed to eat, in order to test to see if this was going to help. These foods either have a unique protein (that your cat has NEVER eaten before – things like venison, duck, rabbit, salmon) or a hydrolyzed protein (that is partly broken down so the body does not recognize it and react to it). Here is more about this issue, including some examples of foods: http://www.marvistavet.com/html/body_food_allergies.html
4. Reduce carbohydrates (CHO's)
For many cats, the CHOs can make diarrhea worse.
So, it is a good idea to offer a high quality canned, low-carb diet, such as Evo 95.
Another option would be a lightly cooked raw diet (Nature's Variety or Companion or Primal) WITH the probiotic. This combination is often effective!
I wish there were more I could do to help you with this very challenging problem. I'm sorry I don't have a magic solution for you. It sounds as though your vet has been very thorough!
If this has been helpful, please "Accept" my answer and leave feedback. I will still be here tomorrow to provide more information if you need it!
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.
Thanks for your help we are going to recomend the Metronidazole to the Vet. Thanks Again
1. My favourite option is to give medications in Pill Pockets.
These are little squishy treats that come in chicken and salmon flavour and have a divot in the middle in which you can hide a treat. I would say that 90% of cats will happily take a pill with these. Here is more about them:
2. Many cats will take a pill if it has a smear of smoked salmon cream cheese on it.
3. You could try hairball control Pounce treats, which get fairly squishy if you add a drop of water to them. Then, you can hide the medication inside it.
4. Try a little squirt of cheese spray
5. Offer the pill in 1/8th teaspoon of ice cream or plain yogurt
6. Hide the pill in a small piece of melon, which many cats love oddly enough.
7. Buy some jars of baby food in meat flavours and offer those as a treat. Read the ingredients carefully to avoid onions, onion powder and garlic and garlic powder. BeechNut make a few that are just meat. One is "turkey in turkey broth" and another "beef in beef broth." They are both popular with cats, and you may be able to hide the pills in 1/4 teaspoon of that. Here's a link:
8. Your veterinarian could provide you with cans of a/d which is a very tasty food used to help sick animals to recover. It is probably the food that I have had most success with to tempt finicky cats to eat. You could hide a pill in 1/4 tsp of this. Here is a link to it: http://www.hillspet.com/hillspet/products/productDetails.hjsp?PRODUCT<>prd_id=845524441760567
9. A compounding pharmacy could make the medications up into a palatable liquid, or a tasty chewable formula, or even a gel that can be applied to the inside of the ear where it can be absorbed across the skin (not all medications are well absorbed this way, however). Pharmacists can make things in triple fish flavour, or chicken or beef or others to suit the patient.
I often use the liquid in triple fish when I treat with metronidazole, as I quite often will do a 3 week course. This seems to be less offensive to cats than many other options!
10. Have your vet or technician teach you how to give a pill by putting it at the back of the cat's mouth. There are some excellent directions here on how to do it: http://www.marvistavet.com/html/pilling_a_cat.html http://www.peteducation.com/article.cfm?c=1+2230&aid=1064
11. If your cat is difficult to give a pill to, you can use a Pill Popper. This is a device that puts the pill at the back of her throat. You can see how to use it here: http://www.expertvillage.com/video/9900_cat-first-aid-health-pill-popper.htm http://www.wonderhowto.com/how-to/video/how-to-give-your-cat-a-pill-or-capsule-79004/
My guess is that you will have to move through this list and try different things at different times to give your cat her medications. However, I do hope that you will find that many of these work for you so that this does not become a struggle and so that you can maintain the loving relationship you have with your cat!