Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to see that you have been waiting quite a while for a response. I think that the trouble is that there are not any good research studies that have outlined a successful treatment for peripheral neuropathy of Bengal cats, which causes demyelination and remyelination of their peripheral nerve fibers.
What are Jaxx's symptoms and how was he diagnosed?
While peripheral neuropathy is possible he is a bit old to be showing symptoms for the first time, (most cats are a year of age or less), It is usually more of a generalized weakness (although rear legs may be more affected) and a loss of feeling and loss of nerve spinal reflexes. If he seems painful then that makes it even less likely.
While this disease may also worsen suddenly there is usually at least a short course and signs of some weakness before things suddenly change. Is that how he has progressed?
Has he had radiographs, and blood work checked and all was within normal limits?
Things such as changes in blood calcium, potassium and glucose levels can all cause neuropathy type symptoms, as could a spinal tumor. Did they also test for feline leukemia, feline immunodeficiency virus and toxoplasmosis? If not those tests should be done.
I would be hesitant still to diagnose this condition without a muscle and nerve biopsy of the affected limbs. Other possible causes could be related to toxin exposure (organophosphates), a blood clot lodged in the blood vessel that supplies blood to his rear legs, or intervertebral disc disease. Intervertebral discs are the spongy cushions between the individual vertebrae in their back and neck. These spongy discs can move or rupture and place pressure upon the spinal cord which can lead to pain, and in severe cases paralysis. Radiographs can sometimes be diagnostic in cases of intervertebral disc disease but often early on in the disease process, because the discs are soft tissue not bone, everything will look normal. An MRI is the best way of diagnosing disc disease.
The good news is that if this is peripheral polyneuropathy a good number of these kitties seem to get better with no treatment, just time and supportive care.
This is the study that gives a good, basic outline of the effects of the disease process on these kitties's nerves if you'd like to read more: http://www.ncbi.nlm.nih.gov/pubmed/21689154
If he has had extensive testing to rule out other diseases and has had nerve and muscle biopsies and has seen a neurologist they may have told you that treatment is unrewarding in most of these kitties, and many given time will recover at least somewhat without any treatment. I know it is hard to do nothing seeing your fellow like he is now. Some veterinarians recommend anti-inflammatories (steroids like Prednisone or non steroidals like Metacam or Onsior), and immunosuppressive drugs like cyclosporine, but there aren't any studies that prove they help, and there are a fair number of cats that get better with no treatment. If I had to pick I would use Prednisone.
The reason that I believe a biopsy is best if he has not had one is that then we know exactly what he has. If this is intervertebral disc disease I would be more aggressive pushing steroids. If this is polyneuropathy I would discuss the lack of evidence that anti-inflammatories help and we could decide to use them or not together.
Some people have trouble doing nothing, and it makes them feel better to do something, even if we aren't sure it will help. If this were my kitty and I had biopsy confirmation I wouldn't medicate him, but that's my personal feeling and I wouldn't force that on someone else. If he hasn't been tested for Toxoplasmosis, Feline Leukemia and Feline Immunodeficiency viruses then I would not use steroids or high doses of immunosuppressive drugs. I don't feel that the possible risk of making those diseases worse if they are present is worth it.
Physical therapy would be good to retain flexibility and try to build strength. Passive range of motion exercises and asking him to push back with his rear legs against your hand seems reasonable. I would consult with a veterinary physical therapist beyond that.
I know that you were looking for a treatment plan, but I hope that what I wrote about the lack of proof of success of any treatments tried so far makes sense.
Please let me know if you have any further questions.