Hi Customer (name blocked for privacy),
A separation, as applied to this, is nearly the same as a fracture. Separation is the pulling apart of two adjacent vertebra, and is frequently seen when an animal has it's tail pulled very roughly. This usually causes trauma to the nervous tissue at the site, with severity depending on the degree of separation. It can effectively be the same as cutting the spinal cord, or nerve in this case, as at the base of the tail the spinal cord has ended, and just nerves to the tail continue downward.
Trauma to the back, as from a blow, can cause injury to the spinal cord or the nerves coming from it. This is like being 'bruised', where the cord swells slightly and can shut down completely for a period of a few days ('spinal shock'),
More severe injury resulting in some degree of fracture may cause compressive injury which can cause anywhere from permanent damage to complete destruction of the cord at the site. A severe degree of fracture usually causes direct cord damage, from local to complete severance of tissue.
From the effects you describe, ie. incontinence, paralysis of the tail and weakness of one leg, I suspect the damage is higher on the spinal column than the tail. As I said earlier,at the level of the tail, the spinal cord has ended, and what remains are just descending nerves to the tail.
Separation of the tail anywhere may damage nerves enough to produce paralysis below the site. The other problems probably stem from blunt trauma to the lower lumbar cord, where nerves controlling the leg, bladder, and bowel function exit the spinal cord.
There is no way to forecast at this point whether this is a permanent or temporary result of the incident, lacking any radiographic evidence of more severe bone damage.
Antibiotics, anti-inflammatories (cortisone) and time are the weapons available to us at this time. More extensive, and expensive, diagnostics are available to determine the extent of damage, MRI comes to mind, but therapy would be not much different than what is going on now.
Periodic expression of the bladder is most important to prevent urinary tract problems. If everything else works out, but the tail remains paralyzed, amputation will probably be recommended.
I hope this answers your questions, and I wish you my best for a happy outcome.
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