Expert: Jessica - 7/10/2010

Question
Hi--a few months ago, our cat had severe weakness in his hind legs. (We got him at a cat shelter; he had a cold for a while after we got him. He tested negative for feline aids.) The vet took X-rays only (since we couldn't afford that AND blood work.) She suspects the cat has FIP, however he doesn't show any other symptoms than hind leg weakness. She prescribed prednisone, which did wonders and, before long, he was scampering around again. It's been about a month that he's been weaned off the prednisone. Sadly, within the last two days, I've noticed a big change in his activity level:  he no longer jumps up onto the window sill, won't jump off our bed, etc., etc. He's taking the same course he did before we started him on prednisone. I've been giving him methyl B-12 (5 mg per day) for a month or so now, which is suggested for cats with diabetes. Because he's showing weakness again, I don't think he has diabetes. What else could it be? Any suggestions or help would be sooo appreciated. Thank you.

Answer
Hi Christine,

Since he has relapsed after being taken off the prednisone, which is a strong anti-inflammatory and also has some immune suppressing properties, this is a strong indication that the condition your kitty is suffering is inflammatory or immune driven in nature.  It's recommended that cats with FIP stay on prednisone permanently for both reasons.  The first benefit is because the immune response to the corona virus is what actually causes the condition, FIP.  Prednisone helps suppress the over active immune response to try to slow the progression of the disease.  Secondly, there is a lot of inflammation of the tissues, especially the peritoneum, which may cause the cat discomfort.  Prednisone can reduce this inflammation to help the cat feel better.  It also tends to increase appetite, which in turn boosts energy.  The risks of keeping a cat on prednisone are so low that there is no reason not to keep an FIP+ cat on prednisone for the rest of his life.

There could be other possibilities.  Infections like toxoplasmosis can create cysts that lead to neurological problems like hind-leg weakness.  While prednisone wouldn't be expected to make such a big difference in your kitty's behavior here, it's possible that it reduced a bit of inflammation to relieve some symptoms.  Additionally, sometimes cats with toxo have symptoms that come and go.  Many years ago, I had a cat with hind-leg weakness, who vets diagnosed with "probable FIP".  I know the disease all too well, and prepared to lose him, but grasping at straws, I asked if toxoplasmosis could be causing his problem.  They agreed to treat him with the antibiotic, clindamycin.  The cat lived for another 10 years before dying of cancer.  While he was never tested for FIP or toxoplasmosis, his leg weakness went away with the clindamycin treatment and never came back!

Some auto immune diseases could also be a possibility, but most of these tend to cause other problems, such as joint pain or skin lesions.  There are always the odd conditions that don't cause any outward signs, though.

I think it would be a really good idea to talk to your vet about putting the kitty right back on the prednisone.  Either it was helping him a great deal, or your cat's relapse is an awful big coincidence.

If you happen to have saved up enough money for some blood work, I would strongly recommend it.  Even if you can afford a very basic blood chemistry panel, that will let you in on his blood counts.  His blood cell counts and protein levels alone will give your vet a very good idea if his condition is consistent with the typical FIP kitty, even without an "FIP" test, and they can indicate whether the cat seems to have an infection that needs treating or appears to have more of an inflammatory process going on.

I agree that your cat is probably not diabetic.  The Methyl B-12 is good for healing neuropathy once glucose is controlled, but I don't think you would have seen any improvement if your kitty was diabetic but not on any insulin.  Nonetheless, it won't do him any harm, as B-12 has all sorts of healing powers!

Best of luck to you!

Jessica