Has he been checked for hip dysplasia? Or a slipped disc or something like that? Try to keep him comfortable and warm until you can get more testing done.
I can't understand why your vet says everything is ok. It plainly isn't and if it were me I'd ask for a second opinion.
Is this a change or has he always done it? I'm not sure what RTG and USG are.
I checked with another vet… but nothing new
USG - ultrasound examination
X-ray - examination
If the x-rays and ultrasound are okay, it could be a neurological problem. Is your dog having seizures or tics? If seizures, how long do they last? It is sometimes difficult to see tics unless the dog is standing still and not moving. The tics remind me of a human with Parkinson's.
It could be Degenerative Myelopathy which is a loss of coordination of the rear legs and it eventually progresses to weakness and then paralysis. There is a DNA test for this through OFA.
If it is possible, I would contact a neurologist if all the tests are normal.
Jennifer
I'm so sorry to hear about your sick B. Shivering and trembling can be due to pain, as well as cold. If his hips go down, it could be arthritis or a disc/spinal problem, and hip dysplasia does sound like something to check. Basenjis are stoic little dogs– they can hide pain for a long time, and shivering in an old dog is not uncommon and arthritic pain, especially on cold, damp days-- is so often the culprit. Did you see the X-rays? Hopefully, that gave you some guidance. Hope the little guy feels better!
Have they tested for Botulism or Lyme Disease?
Hmmm i think no. I checked wide blood test - everything and additional blod test thyroid. Could you tell me more about Botulism or Lyme Disease tests? Name of this tests? In Poland basenji are very very rare so vets don't know so much about it.
I am not sure how they test for either. Lyme disease is caused by a Tick…..can cause paralysis and a whole range of othe symptoms. Botulism is caused by eating tainted meat or food. I imagine it would just be a blood test. Just ask your vet if they have tested for that or if they can test for it.
thanks. I'll take a look for ticks 
Yes, the test for Lyme disease is a blood test. It is a special test that is not in the regular panels– they usually run it separately, after they rule out other things. I hope your B is better! Did you find out what was wrong?
